diff --git a/.gitignore b/.gitignore
index 5a7f6ebca5be..eb6b1f6dfbf2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -98,6 +98,7 @@ plugins/cln-currencyrate
 
 # Build directories
 bionic/
+build/
 focal/
 jammy/
 noble/
diff --git a/Makefile b/Makefile
index 20d4aedff053..ce2e41bb9657 100644
--- a/Makefile
+++ b/Makefile
@@ -39,6 +39,91 @@ BOLTVERSION := $(DEFAULT_BOLTVERSION)
 
 -include config.vars
 
+ifdef BUILD
+AR_FOR_BUILD ?= $(BUILD)-ar
+CC_FOR_BUILD ?= $(BUILD)-cc
+else
+AR_FOR_BUILD ?= ar
+CC_FOR_BUILD ?= cc
+endif
+
+# Save flags inherited from environment (or config.vars) before we start munging them
+CFLAGS_FROM_ENV := $(CFLAGS)
+CFLAGS =
+CPPFLAGS_FROM_ENV := $(CPPFLAGS)
+CPPFLAGS =
+LDFLAGS_FROM_ENV := $(LDFLAGS)
+LDFLAGS =
+ifneq ($(origin CFLAGS_FOR_BUILD),undefined)
+CFLAGS_FOR_BUILD_FROM_ENV := $(CFLAGS_FOR_BUILD)
+endif
+CFLAGS_FOR_BUILD =
+ifneq ($(origin CPPFLAGS_FOR_BUILD),undefined)
+CPPFLAGS_FOR_BUILD_FROM_ENV := $(CPPFLAGS_FOR_BUILD)
+endif
+CPPFLAGS_FOR_BUILD =
+ifneq ($(origin LDFLAGS_FOR_BUILD),undefined)
+LDFLAGS_FOR_BUILD_FROM_ENV := $(LDFLAGS_FOR_BUILD)
+endif
+LDFLAGS_FOR_BUILD =
+
+# Determine whether we are cross-building
+CROSS_BUILD := 1
+ifeq ($(CC_FOR_BUILD),$(CC))
+CFLAGS_FOR_BUILD_FROM_ENV ?= $(CFLAGS_FROM_ENV)
+CPPFLAGS_FOR_BUILD_FROM_ENV ?= $(CPPFLAGS_FROM_ENV)
+LDFLAGS_FOR_BUILD_FROM_ENV ?= $(LDFLAGS_FROM_ENV)
+ifeq ($(CFLAGS_FOR_BUILD_FROM_ENV),$(CFLAGS_FROM_ENV))
+ifeq ($(CPPFLAGS_FOR_BUILD_FROM_ENV),$(CPPFLAGS_FROM_ENV))
+ifeq ($(LDFLAGS_FOR_BUILD_FROM_ENV),$(LDFLAGS_FROM_ENV))
+undefine CROSS_BUILD
+endif
+endif
+endif
+endif
+
+# Look up the host machine tuple if not specified
+ifndef HOST
+HOST := $(shell $(CC) $(CFLAGS_FROM_ENV) -dumpmachine)
+endif
+
+# Look up the build machine tuple if not specified
+ifndef BUILD
+ifdef CROSS_BUILD
+BUILD := $(shell $(CC_FOR_BUILD) $(CFLAGS_FOR_BUILD_FROM_ENV) -dumpmachine)
+else
+BUILD := $(HOST)
+endif
+endif
+
+# Set a default host-machine build directory if not specified
+ifndef BUILDDIR
+BUILDDIR := build/$(HOST)
+endif
+
+# Set a default build-machine build directory if not specified
+ifndef BUILDDIR_FOR_BUILD
+ifdef CROSS_BUILD
+ifneq ($(BUILD),$(HOST))
+BUILDDIR_FOR_BUILD := build/$(BUILD)
+else
+BUILDDIR_FOR_BUILD := $(BUILDDIR).build
+endif
+else
+BUILDDIR_FOR_BUILD := $(BUILDDIR)
+endif
+endif
+
+# Override toolchain when building targets for build machine
+ifdef CROSS_BUILD
+$(BUILDDIR_FOR_BUILD)/%: override CC = $(CC_FOR_BUILD)
+$(BUILDDIR_FOR_BUILD)/%: override CFLAGS = $(CFLAGS_FOR_BUILD)
+$(BUILDDIR_FOR_BUILD)/%: override CPPFLAGS = $(CPPFLAGS_FOR_BUILD)
+$(BUILDDIR_FOR_BUILD)/%: override LDFLAGS = $(LDFLAGS_FOR_BUILD)
+$(BUILDDIR_FOR_BUILD)/%: override LDLIBS = $(LDLIBS_FOR_BUILD)
+$(BUILDDIR_FOR_BUILD)/%: override EXTERNAL_LDLIBS = $(EXTERNAL_LDLIBS_FOR_BUILD)
+endif
+
 # Use Homebrew LLVM toolchain for fuzzing support on macOS
 ifeq ($(OS),Darwin)
 export PATH := /opt/homebrew/opt/llvm/bin:$(PATH)
@@ -100,136 +185,151 @@ PYTHON_GENERATED= \
 FEATURES :=
 
 CCAN_OBJS :=					\
-	ccan-asort.o				\
-	ccan-base64.o				\
-	ccan-bitmap.o				\
-	ccan-bitops.o				\
-	ccan-breakpoint.o			\
-	ccan-cdump.o				\
-	ccan-closefrom.o			\
-	ccan-crc32c.o				\
-	ccan-crypto-hmac.o			\
-	ccan-crypto-hkdf.o			\
-	ccan-crypto-ripemd160.o			\
-	ccan-crypto-sha256.o			\
-	ccan-crypto-shachain.o			\
-	ccan-crypto-siphash24.o			\
-	ccan-err.o				\
-	ccan-fdpass.o				\
-	ccan-htable.o				\
-	ccan-ilog.o				\
-	ccan-io-io.o				\
-	ccan-intmap.o				\
-	ccan-io-poll.o				\
-	ccan-io-fdpass.o			\
-	ccan-isaac.o				\
-	ccan-isaac64.o				\
-	ccan-json_escape.o			\
-	ccan-json_out.o				\
-	ccan-list.o				\
-	ccan-mem.o				\
-	ccan-membuf.o				\
-	ccan-noerr.o				\
-	ccan-opt-helpers.o			\
-	ccan-opt-parse.o			\
-	ccan-opt-usage.o			\
-	ccan-opt.o				\
-	ccan-pipecmd.o				\
-	ccan-ptr_valid.o			\
-	ccan-rbuf.o				\
-	ccan-read_write_all.o			\
-	ccan-rune-coding.o			\
-	ccan-rune-rune.o			\
-	ccan-str-base32.o			\
-	ccan-str-hex.o				\
-	ccan-str.o				\
-	ccan-strmap.o				\
-	ccan-strset.o				\
-	ccan-take.o				\
-	ccan-tal-grab_file.o			\
-	ccan-tal-link.o				\
-	ccan-tal-path.o				\
-	ccan-tal-str.o				\
-	ccan-tal.o				\
-	ccan-time.o				\
-	ccan-timer.o				\
-	ccan-utf8.o
-
-CCAN_HEADERS :=						\
-	$(CCANDIR)/config.h				\
-	$(CCANDIR)/ccan/alignof/alignof.h		\
-	$(CCANDIR)/ccan/array_size/array_size.h		\
-	$(CCANDIR)/ccan/asort/asort.h			\
-	$(CCANDIR)/ccan/base64/base64.h			\
-	$(CCANDIR)/ccan/bitmap/bitmap.h			\
-	$(CCANDIR)/ccan/bitops/bitops.h			\
-	$(CCANDIR)/ccan/breakpoint/breakpoint.h		\
-	$(CCANDIR)/ccan/build_assert/build_assert.h	\
-	$(CCANDIR)/ccan/cast/cast.h			\
-	$(CCANDIR)/ccan/cdump/cdump.h			\
-	$(CCANDIR)/ccan/check_type/check_type.h		\
-	$(CCANDIR)/ccan/closefrom/closefrom.h		\
-	$(CCANDIR)/ccan/compiler/compiler.h		\
-	$(CCANDIR)/ccan/container_of/container_of.h	\
-	$(CCANDIR)/ccan/cppmagic/cppmagic.h		\
-	$(CCANDIR)/ccan/crc32c/crc32c.h			\
-	$(CCANDIR)/ccan/crypto/hkdf_sha256/hkdf_sha256.h \
-	$(CCANDIR)/ccan/crypto/hmac_sha256/hmac_sha256.h \
-	$(CCANDIR)/ccan/crypto/ripemd160/ripemd160.h	\
-	$(CCANDIR)/ccan/crypto/sha256/sha256.h		\
-	$(CCANDIR)/ccan/crypto/shachain/shachain.h	\
-	$(CCANDIR)/ccan/crypto/siphash24/siphash24.h	\
-	$(CCANDIR)/ccan/endian/endian.h			\
-	$(CCANDIR)/ccan/err/err.h			\
-	$(CCANDIR)/ccan/fdpass/fdpass.h			\
-	$(CCANDIR)/ccan/graphql/graphql.h		\
-	$(CCANDIR)/ccan/htable/htable.h			\
-	$(CCANDIR)/ccan/htable/htable_type.h		\
-	$(CCANDIR)/ccan/ilog/ilog.h			\
-	$(CCANDIR)/ccan/intmap/intmap.h			\
-	$(CCANDIR)/ccan/io/backend.h			\
-	$(CCANDIR)/ccan/io/fdpass/fdpass.h		\
-	$(CCANDIR)/ccan/io/io.h				\
-	$(CCANDIR)/ccan/io/io_plan.h			\
-	$(CCANDIR)/ccan/isaac/isaac.h			\
-	$(CCANDIR)/ccan/isaac/isaac64.h			\
-	$(CCANDIR)/ccan/json_escape/json_escape.h	\
-	$(CCANDIR)/ccan/json_out/json_out.h		\
-	$(CCANDIR)/ccan/likely/likely.h			\
-	$(CCANDIR)/ccan/list/list.h			\
-	$(CCANDIR)/ccan/lqueue/lqueue.h			\
-	$(CCANDIR)/ccan/mem/mem.h			\
-	$(CCANDIR)/ccan/membuf/membuf.h			\
-	$(CCANDIR)/ccan/noerr/noerr.h			\
-	$(CCANDIR)/ccan/opt/opt.h			\
-	$(CCANDIR)/ccan/opt/private.h			\
-	$(CCANDIR)/ccan/order/order.h			\
-	$(CCANDIR)/ccan/pipecmd/pipecmd.h		\
-	$(CCANDIR)/ccan/ptr_valid/ptr_valid.h		\
-	$(CCANDIR)/ccan/ptrint/ptrint.h			\
-	$(CCANDIR)/ccan/rbuf/rbuf.h			\
-	$(CCANDIR)/ccan/read_write_all/read_write_all.h	\
-	$(CCANDIR)/ccan/rune/internal.h			\
-	$(CCANDIR)/ccan/rune/rune.h			\
-	$(CCANDIR)/ccan/short_types/short_types.h	\
-	$(CCANDIR)/ccan/str/base32/base32.h		\
-	$(CCANDIR)/ccan/str/hex/hex.h			\
-	$(CCANDIR)/ccan/str/str.h			\
-	$(CCANDIR)/ccan/str/str_debug.h			\
-	$(CCANDIR)/ccan/strmap/strmap.h			\
-	$(CCANDIR)/ccan/strset/strset.h			\
-	$(CCANDIR)/ccan/structeq/structeq.h		\
-	$(CCANDIR)/ccan/take/take.h			\
-	$(CCANDIR)/ccan/tal/grab_file/grab_file.h	\
-	$(CCANDIR)/ccan/tal/link/link.h			\
-	$(CCANDIR)/ccan/tal/path/path.h			\
-	$(CCANDIR)/ccan/tal/str/str.h			\
-	$(CCANDIR)/ccan/tal/tal.h			\
-	$(CCANDIR)/ccan/tcon/tcon.h			\
-	$(CCANDIR)/ccan/time/time.h			\
-	$(CCANDIR)/ccan/timer/timer.h			\
-	$(CCANDIR)/ccan/typesafe_cb/typesafe_cb.h	\
-	$(CCANDIR)/ccan/utf8/utf8.h
+	$(addprefix $(BUILDDIR)/$(CCANDIR)/ccan/, \
+	asort/asort.o				\
+	base64/base64.o				\
+	bitmap/bitmap.o				\
+	bitops/bitops.o				\
+	breakpoint/breakpoint.o			\
+	closefrom/closefrom.o			\
+	crc32c/crc32c.o				\
+	crypto/hkdf_sha256/hkdf_sha256.o	\
+	crypto/hmac_sha256/hmac_sha256.o	\
+	crypto/ripemd160/ripemd160.o		\
+	crypto/sha256/sha256.o			\
+	crypto/shachain/shachain.o		\
+	crypto/siphash24/siphash24.o		\
+	err/err.o				\
+	fdpass/fdpass.o				\
+	htable/htable.o				\
+	ilog/ilog.o				\
+	intmap/intmap.o				\
+	io/fdpass/fdpass.o			\
+	io/io.o					\
+	io/poll.o				\
+	isaac/isaac.o				\
+	isaac/isaac64.o				\
+	json_escape/json_escape.o		\
+	json_out/json_out.o			\
+	list/list.o				\
+	mem/mem.o				\
+	membuf/membuf.o				\
+	noerr/noerr.o				\
+	opt/helpers.o				\
+	opt/opt.o				\
+	opt/parse.o				\
+	opt/usage.o				\
+	pipecmd/pipecmd.o			\
+	ptr_valid/ptr_valid.o			\
+	rbuf/rbuf.o				\
+	read_write_all/read_write_all.o		\
+	rune/coding.o				\
+	rune/rune.o				\
+	str/base32/base32.o			\
+	str/hex/hex.o				\
+	str/str.o				\
+	strmap/strmap.o				\
+	strset/strset.o				\
+	take/take.o				\
+	tal/grab_file/grab_file.o		\
+	tal/link/link.o				\
+	tal/path/path.o				\
+	tal/str/str.o				\
+	tal/tal.o				\
+	time/time.o				\
+	timer/timer.o				\
+	utf8/utf8.o				\
+	)
+
+CCAN_BUILD_OBJS :=				\
+	$(addprefix $(BUILDDIR_FOR_BUILD)/$(CCANDIR)/ccan/, \
+	cdump/cdump.o				\
+	list/list.o				\
+	noerr/noerr.o				\
+	strmap/strmap.o				\
+	take/take.o				\
+	tal/grab_file/grab_file.o		\
+	tal/str/str.o				\
+	tal/tal.o				\
+	)
+
+CCAN_HEADERS :=					\
+	$(CCANDIR)/config.h			\
+	$(addprefix $(CCANDIR)/ccan/,		\
+	alignof/alignof.h			\
+	array_size/array_size.h			\
+	asort/asort.h				\
+	base64/base64.h				\
+	bitmap/bitmap.h				\
+	bitops/bitops.h				\
+	breakpoint/breakpoint.h			\
+	build_assert/build_assert.h		\
+	cast/cast.h				\
+	cdump/cdump.h				\
+	check_type/check_type.h			\
+	closefrom/closefrom.h			\
+	compiler/compiler.h			\
+	container_of/container_of.h		\
+	cppmagic/cppmagic.h			\
+	crc32c/crc32c.h				\
+	crypto/hkdf_sha256/hkdf_sha256.h 	\
+	crypto/hmac_sha256/hmac_sha256.h	\
+	crypto/ripemd160/ripemd160.h		\
+	crypto/sha256/sha256.h			\
+	crypto/shachain/shachain.h		\
+	crypto/siphash24/siphash24.h		\
+	endian/endian.h				\
+	err/err.h				\
+	fdpass/fdpass.h				\
+	graphql/graphql.h			\
+	htable/htable.h				\
+	htable/htable_type.h			\
+	ilog/ilog.h				\
+	intmap/intmap.h				\
+	io/backend.h				\
+	io/fdpass/fdpass.h			\
+	io/io.h					\
+	io/io_plan.h				\
+	isaac/isaac.h				\
+	isaac/isaac64.h				\
+	json_escape/json_escape.h		\
+	json_out/json_out.h			\
+	likely/likely.h				\
+	list/list.h				\
+	lqueue/lqueue.h				\
+	mem/mem.h				\
+	membuf/membuf.h				\
+	noerr/noerr.h				\
+	opt/opt.h				\
+	opt/private.h				\
+	order/order.h				\
+	pipecmd/pipecmd.h			\
+	ptr_valid/ptr_valid.h			\
+	ptrint/ptrint.h				\
+	rbuf/rbuf.h				\
+	read_write_all/read_write_all.h		\
+	rune/internal.h				\
+	rune/rune.h				\
+	short_types/short_types.h		\
+	str/base32/base32.h			\
+	str/hex/hex.h				\
+	str/str.h				\
+	str/str_debug.h				\
+	strmap/strmap.h				\
+	strset/strset.h				\
+	structeq/structeq.h			\
+	take/take.h				\
+	tal/grab_file/grab_file.h		\
+	tal/link/link.h				\
+	tal/path/path.h				\
+	tal/str/str.h				\
+	tal/tal.h				\
+	tcon/tcon.h				\
+	time/time.h				\
+	timer/timer.h				\
+	typesafe_cb/typesafe_cb.h		\
+	utf8/utf8.h				\
+	)
 
 BOLT_GEN := tools/generate-wire.py
 WIRE_GEN := $(BOLT_GEN)
@@ -239,6 +339,7 @@ WIRE_GEN_DEPS := $(WIRE_GEN) $(wildcard tools/gen/*_template)
 
 # These are filled by individual Makefiles
 ALL_PROGRAMS :=
+ALL_BUILD_PROGRAMS :=
 ALL_TEST_PROGRAMS :=
 ALL_TEST_GEN :=
 ALL_FUZZ_TARGETS :=
@@ -289,8 +390,14 @@ PKG_CONFIG_PATH := $(SQLITE_PREFIX)/lib/pkgconfig:$(PKG_CONFIG_PATH)
 endif
 endif
 
-CPPFLAGS += -DCLN_NEXT_VERSION="\"$(CLN_NEXT_VERSION)\"" -DPKGLIBEXECDIR="\"$(pkglibexecdir)\"" -DBINDIR="\"$(bindir)\"" -DPLUGINDIR="\"$(plugindir)\"" -DCCAN_TAL_NEVER_RETURN_NULL=1
-CFLAGS = $(CPPFLAGS) $(CWARNFLAGS) $(CDEBUGFLAGS) $(COPTFLAGS) -I $(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I . -I$(CPATH) $(SQLITE3_CFLAGS) $(SODIUM_CFLAGS) $(POSTGRES_INCLUDE) $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) -DSHACHAIN_BITS=48 -DJSMN_PARENT_LINKS $(PIE_CFLAGS) $(COMPAT_CFLAGS) $(CSANFLAGS)
+# Put the environment-inherited flags *last* so the user has the final say.
+CPPFLAGS += -DCLN_NEXT_VERSION="\"$(CLN_NEXT_VERSION)\"" -DPKGLIBEXECDIR="\"$(pkglibexecdir)\"" -DBINDIR="\"$(bindir)\"" -DPLUGINDIR="\"$(plugindir)\"" -DCCAN_TAL_NEVER_RETURN_NULL=1 -I$(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I. -I$(BUILDDIR) -I$(CPATH) $(POSTGRES_INCLUDE) -DSHACHAIN_BITS=48 -DJSMN_PARENT_LINKS $(COMPAT_CFLAGS) $(CPPFLAGS_FROM_ENV)
+CFLAGS = $(CWARNFLAGS) $(CDEBUGFLAGS) $(COPTFLAGS) $(SQLITE3_CFLAGS) $(SODIUM_CFLAGS) $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) $(PIE_CFLAGS) $(CSANFLAGS) $(CFLAGS_FROM_ENV)
+LDFLAGS += $(PIE_LDFLAGS) $(LDFLAGS_FROM_ENV)
+
+CFLAGS_FOR_BUILD = $(CWARNFLAGS) $(CFLAGS_FOR_BUILD_FROM_ENV)
+CPPFLAGS_FOR_BUILD = -I$(CCANDIR) -I. $(CPPFLAGS_FOR_BUILD_FROM_ENV)
+LDFLAGS_FOR_BUILD = $(LDFLAGS_FOR_BUILD_FROM_ENV)
 
 # If CFLAGS is already set in the environment of make (to whatever value, it
 # does not matter) then it would export it to subprocesses with the above value
@@ -302,8 +409,6 @@ unexport CFLAGS
 # We can get configurator to run a different compile cmd to cross-configure.
 CONFIGURATOR_CC := $(CC)
 
-LDFLAGS += $(PIE_LDFLAGS) $(CSANFLAGS) $(COPTFLAGS)
-
 ifeq ($(STATIC),1)
 # For MacOS, Jacob Rapoport <jacob@rumblemonkey.com> changed this to:
 #  -L/usr/local/lib -lsqlite3 -lz -Wl,-lm -lpthread -ldl $(COVFLAGS)
@@ -313,10 +418,6 @@ else
 LDLIBS = -L$(CPATH) -lm $(SQLITE3_LDLIBS) $(COVFLAGS)
 endif
 
-ifeq ($(HAVE_FUNCTION_SECTIONS),1)
-LDLIBS += -Wl,--gc-sections
-endif
-
 # If we have the postgres client library we need to link against it as well
 ifeq ($(HAVE_POSTGRES),1)
 LDLIBS += $(POSTGRES_LDLIBS)
@@ -330,16 +431,21 @@ FORCE:
 endif
 
 show-flags: config.vars
-	@$(ECHO) "CC: $(CC) $(CFLAGS) -c -o"
-	@$(ECHO) "LD: $(LINK.o) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) -o"
+	@$(ECHO) "CC: $(COMPILE.c) -o"
+	@$(ECHO) "LD: $(LINK.c) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) -o"
 
 # We will re-generate, but we won't generate for the first time!
 ccan/config.h config.vars &: configure ccan/tools/configurator/configurator.c
 	@if [ ! -f config.vars ]; then echo 'File config.vars not found: you must run ./configure before running make.' >&2; exit 1; fi
 	./configure --reconfigure
 
-%.o: %.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
+%/:
+	@$(MKDIR_P) $(@D)
+
+# Update all archive members using a single ar invocation. This un-breaks parallel Make.
+(%) : % ;
+%.a :
+	@$(call VERBOSE,"ar $@",$(AR) r $@ $?)
 
 # tools/update-mocks.sh does nasty recursive make, must not do this!
 ifeq ($(SUPPRESS_GENERATION),1)
@@ -354,6 +460,8 @@ SHA256STAMP_CHANGED = [ x"`$(SED) -n 's/.*SHA256STAMP:\([a-f0-9]*\).*/\1/p' $@ 2
 SHA256STAMP = echo "$(1) SHA256STAMP:"`cat $(sort $(filter-out FORCE,$^)) | $(SHA256SUM) | cut -c1-64`"$(2)" >> $@
 endif
 
+CDUMP_ENUMSTR := $(BUILDDIR_FOR_BUILD)/ccan/ccan/cdump/tools/cdump-enumstr
+
 # generate-wire.py --page [header|impl] hdrfilename wirename < csv > file
 %_wiregen.h: %_wire.csv $(WIRE_GEN_DEPS)
 	@if $(call SHA256STAMP_CHANGED); then \
@@ -459,11 +567,14 @@ ALL_NONGEN_SRCFILES := $(ALL_NONGEN_HEADERS) $(ALL_NONGEN_SOURCES)
 # TODO: $(EXEEXT) support for Windows?  Needs more coding for
 # the individual Makefiles, however.
 BIN_PROGRAMS = \
+	$(addprefix $(BUILDDIR)/, \
 	       cli/lightning-cli \
 	       lightningd/lightningd \
 	       tools/lightning-hsmtool\
+	) \
 	       tools/reckless
 PKGLIBEXEC_PROGRAMS = \
+	$(addprefix $(BUILDDIR)/, \
 	       lightningd/lightning_channeld \
 	       lightningd/lightning_closingd \
 	       lightningd/lightning_connectd \
@@ -473,7 +584,8 @@ PKGLIBEXEC_PROGRAMS = \
 	       lightningd/lightning_hsmd \
 	       lightningd/lightning_onchaind \
 	       lightningd/lightning_openingd \
-	       lightningd/lightning_websocketd
+	       lightningd/lightning_websocketd \
+	)
 
 mkdocs.yml: $(MANPAGES:=.md)
 	@$(call VERBOSE, "genidx $@", \
@@ -485,7 +597,7 @@ mkdocs.yml: $(MANPAGES:=.md)
 
 
 # Every single object file.
-ALL_OBJS := $(ALL_C_SOURCES:.c=.o)
+ALL_OBJS := $(ALL_C_SOURCES:%.c=$(BUILDDIR)/%.o)
 
 WIREGEN_FILES := $(filter %printgen.h %printgen.c %wiregen.h %wiregen.c, $(ALL_C_HEADERS) $(ALL_C_SOURCES))
 
@@ -757,11 +869,9 @@ TAGS:
 tags:
 	$(RM) tags; find * -name test -type d -prune -o \( -name '*.[ch]' -o -name '*.py' \) -print0 | xargs -0 ctags --append
 
-ccan/ccan/cdump/tools/cdump-enumstr: ccan/ccan/cdump/tools/cdump-enumstr.o libccan.a
-
-ALL_PROGRAMS += ccan/ccan/cdump/tools/cdump-enumstr
+ALL_BUILD_PROGRAMS += $(CDUMP_ENUMSTR)
 # Can't add to ALL_OBJS, as that makes a circular dep.
-ccan/ccan/cdump/tools/cdump-enumstr.o: $(CCAN_HEADERS) Makefile
+$(CDUMP_ENUMSTR).o: $(CCAN_HEADERS) Makefile
 
 # Without a working git, you can't generate this file, so assume if it exists
 # it is ok (fixes "sudo make install").
@@ -775,30 +885,34 @@ version_gen.h: $(FORCE)
 	@if cmp $@.new $@ >/dev/null 2>&1; then rm -f $@.new; else mv $@.new $@; $(ECHO) Version updated; fi
 endif
 
-# That forces this rule to be run every time, too.
-header_versions_gen.h: tools/headerversions $(FORCE)
-	@tools/headerversions $@
+header_versions_gen.h: tools/header-versions.sh $(FORCE)
+	@HAVE_SQLITE3='$(HAVE_SQLITE3)' \
+		SQLITE3_CFLAGS='$(SQLITE3_CFLAGS)' \
+		$< $@
 
 # Once you have libccan.a, you don't need these.
-.INTERMEDIATE: $(CCAN_OBJS)
+.INTERMEDIATE: $(CCAN_OBJS) $(CCAN_BUILD_OBJS)
 
 # We make a static library, this way linker can discard unused parts.
-libccan.a: $(CCAN_OBJS)
-	@$(call VERBOSE, "ar $@", $(AR) r $@ $(CCAN_OBJS))
+$(BUILDDIR)/libccan.a: $(BUILDDIR)/libccan.a($(CCAN_OBJS))
+$(BUILDDIR_FOR_BUILD)/libccan.a: $(BUILDDIR_FOR_BUILD)/libccan.a($(CCAN_BUILD_OBJS))
 
-# All binaries require the external libs, ccan and system library versions.
-$(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS) $(ALL_FUZZ_TARGETS): $(EXTERNAL_LIBS) libccan.a
+# All host-machine programs require the external libs and ccan.
+$(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS) $(ALL_FUZZ_TARGETS): $(EXTERNAL_LIBS) $(BUILDDIR)/libccan.a
 
-# Each test program depends on its own object.
-$(ALL_TEST_PROGRAMS) $(ALL_FUZZ_TARGETS): %: %.o
+# All build-machine programs require ccan built for the build machine.
+$(ALL_BUILD_PROGRAMS): $(BUILDDIR_FOR_BUILD)/libccan.a
+
+# Each build-time program depends on its own object.
+$(ALL_BUILD_PROGRAMS) $(ALL_TEST_PROGRAMS) $(ALL_FUZZ_TARGETS): %: %.o
 
 # Without this rule, the (built-in) link line contains
 # external/libwallycore.a directly, which causes a symbol clash (it
 # uses some ccan modules internally).  We want to rely on -lwallycore etc.
 # (as per EXTERNAL_LDLIBS) so we filter them out here.  We have to put the other
 # .a files (if any) at the end of the link line.
-$(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS):
-	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) $(filter-out external/%,$(filter %.a,$^)) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) $($(@)_LDLIBS) -o $@)
+$(ALL_PROGRAMS) $(ALL_BUILD_PROGRAMS) $(ALL_TEST_PROGRAMS):
+	@$(call VERBOSE, "ld $@", $(LINK.c) $(filter-out %.a,$^) $(filter-out external/%,$(filter %.a,$^)) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) $($(@)_LDLIBS) -o $@)
 ifeq ($(OS),Darwin)
 	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
 endif
@@ -819,14 +933,14 @@ endif
 endif
 
 $(ALL_FUZZ_TARGETS):
-	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) libcommon.a libccan.a $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) $(FUZZ_LDFLAGS) -o $@)
+	@$(call VERBOSE, "ld $@", $(LINK.c) $(filter-out %.a,$^) $(addprefix $(BUILDDIR)/,libcommon.a libccan.a) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) $(FUZZ_LDFLAGS) -o $@)
 ifeq ($(OS),Darwin)
 	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
 endif
 
 
 # Everything depends on the CCAN headers, and Makefile
-$(CCAN_OBJS) $(CDUMP_OBJS): $(CCAN_HEADERS) Makefile ccan_compat.h
+$(CCAN_OBJS) $(CCAN_BUILD_OBJS): $(CCAN_HEADERS) Makefile ccan_compat.h
 
 # Except for CCAN, we treat everything else as dependent on external/ bitcoin/ common/ wire/ and all generated headers, and Makefile
 $(ALL_OBJS): $(BITCOIN_HEADERS) $(COMMON_HEADERS) $(CCAN_HEADERS) $(WIRE_HEADERS) $(ALL_GEN_HEADERS) $(EXTERNAL_HEADERS) Makefile
@@ -861,19 +975,24 @@ maintainer-clean: distclean
 
 # We used to have gen_ files, now we have _gen files.
 # We used to generate doc/schemas/lightning-sql.json.
-obsclean:
+# headerversions used to be a compiled program.
+# Build products used to land inside the source tree.
+obsclean::
 	$(RM) gen_*.h */gen_*.[ch] */*/gen_*.[ch]
 	$(RM) doc/schemas/lightning-sql.json
+	$(RM) tools/headerversions tools/headerversions.o
+	$(RM) libccan.a
+	$(RM) ccan/ccan/cdump/tools/cdump-enumstr ccan/ccan/cdump/tools/cdump-enumstr.o
+	$(RM) $(ALL_OBJS:$(BUILDDIR)/%=%)
+	$(RM) $(ALL_PROGRAMS:$(BUILDDIR)/%=%)
+	$(RM) $(ALL_TEST_PROGRAMS:$(BUILDDIR)/%=%)
+	$(RM) $(ALL_FUZZ_TARGETS:$(BUILDDIR)/%=%)
 
 clean: obsclean
-	$(RM) libccan.a $(CCAN_OBJS) $(CDUMP_OBJS) $(ALL_OBJS)
+	$(RM) -r $(BUILDDIR) $(BUILDDIR_FOR_BUILD)
 	$(RM) $(ALL_GEN_HEADERS) $(ALL_GEN_SOURCES)
-	$(RM) $(ALL_PROGRAMS)
-	$(RM) $(ALL_TEST_PROGRAMS)
-	$(RM) $(ALL_FUZZ_TARGETS)
 	$(RM) $(MSGGEN_GEN_ALL)
 	$(RM) ccan/tools/configurator/configurator
-	$(RM) ccan/ccan/cdump/tools/cdump-enumstr.o
 	find . -name '*gcda' -delete
 	find . -name '*gcno' -delete
 	find . -name '*.nccout' -delete
@@ -932,7 +1051,7 @@ update-dot-version:
 
 update-mocks: $(ALL_TEST_PROGRAMS:%=update-mocks/%.c)
 
-$(ALL_TEST_PROGRAMS:%=update-mocks/%.c): $(ALL_GEN_HEADERS) $(EXTERNAL_LIBS) libccan.a ccan/ccan/cdump/tools/cdump-enumstr config.vars
+$(ALL_TEST_PROGRAMS:%=update-mocks/%.c): $(ALL_GEN_HEADERS) $(EXTERNAL_LIBS) $(BUILDDIR)/libccan.a $(CDUMP_ENUMSTR) config.vars
 
 update-mocks/%: % $(ALL_GEN_HEADERS) $(ALL_GEN_SOURCES)
 	@MAKE=$(MAKE) SED=$(SED) tools/update-mocks.sh "$*" $(SUPPRESS_OUTPUT)
@@ -946,10 +1065,44 @@ fuzzunittest/%: % bolt-precheck
 
 # Commands
 MKDIR_P = mkdir -p
+RMDIR_P = rmdir -p
+CP_A = cp -a
 INSTALL = install
 INSTALL_PROGRAM = $(INSTALL)
 INSTALL_DATA = $(INSTALL) -m 644
 
+# $(1) = install command
+# $(2) = installation source file
+# $(3) = installation target file
+define INSTALL_RULE_tmpl =
+$(3): $(2) | $(dir $(3))
+	@$$(call VERBOSE,"install $$@",$(1) $$< $$|)
+endef
+
+# $(1) = install command
+# $(2) = list of files to install to $(3)
+# $(3) = installation target directory
+install_targets = $(foreach f,$(2),$(let t,$(3)/$(notdir $(f)),$(eval $(call INSTALL_RULE_tmpl,$(1),$(f),$(t)))$(t)))
+
+# $(1) = list of files to install to $(2)
+# $(2) = installation target directory
+install_program_targets = $(call install_targets,$(INSTALL_PROGRAM),$(1),$(2))
+install_data_targets = $(call install_targets,$(INSTALL_DATA),$(1),$(2))
+
+# Defines a rule that touches $(1) whenever it is older than any file listed in $(2).
+define TOUCH_RULE_tmpl =
+$(1): $(2)
+	@touch $(1)
+endef
+
+# $(1) = list of files whose containing directories are to be installed to $(2)
+# $(2) = installation target directory
+# An installation target rule is defined for each distinct directory containing
+# any file listed in $(1). A containing directory will be touched whenever any
+# listed contained file is newer than it. The touched directory then will
+# trigger a re-installation of the whole directory.
+install_py_plugin_targets = $(foreach d,$(sort $(dir $(1))),$(let t,$(2)/$(notdir $(patsubst %/,%,$(d))),$(eval $(call TOUCH_RULE_tmpl,$(d),$(filter $(d)%,$(1))))$(eval $(call INSTALL_RULE_tmpl,$(RM) -r $$@ && $(CP_A),$(d),$(t)))$(t)))
+
 # Tags needed by some package systems.
 PRE_INSTALL = :
 NORMAL_INSTALL = :
@@ -958,28 +1111,26 @@ PRE_UNINSTALL = :
 NORMAL_UNINSTALL = :
 POST_UNINSTALL = :
 
-# Target to create directories.
-installdirs:
-	@$(NORMAL_INSTALL)
-	$(MKDIR_P) $(DESTDIR)$(bindir)
-	$(MKDIR_P) $(DESTDIR)$(pkglibexecdir)
-	$(MKDIR_P) $(DESTDIR)$(plugindir)
-	$(MKDIR_P) $(DESTDIR)$(man1dir)
-	$(MKDIR_P) $(DESTDIR)$(man5dir)
-	$(MKDIR_P) $(DESTDIR)$(man7dir)
-	$(MKDIR_P) $(DESTDIR)$(man8dir)
-	$(MKDIR_P) $(DESTDIR)$(docdir)
+$(DESTDIR)$(plugindir)/clnrest: uninstall-old-clnrest-plugin
+uninstall-old-clnrest-plugin:
+	@[ -d $(DESTDIR)$(plugindir)/clnrest ] && $(RM) -r $(DESTDIR)$(plugindir)/clnrest
+
+$(DESTDIR)$(plugindir)/wss-proxy: uninstall-old-wss-proxy-plugin
+uninstall-old-wss-proxy-plugin:
+	@[ -d $(DESTDIR)$(plugindir)/wss-proxy ] && $(RM) -r $(DESTDIR)$(plugindir)/wss-proxy
+
+.PHONY: uninstall-old-clnrest-plugin uninstall-old-wss-proxy-plugin
 
 # $(PLUGINS) is defined in plugins/Makefile.
 
-install-program: installdirs $(BIN_PROGRAMS) $(PKGLIBEXEC_PROGRAMS) $(PLUGINS) $(PY_PLUGINS)
+INSTALL_PROGRAM_TARGETS := \
+	$(call install_program_targets,$(BIN_PROGRAMS),$(DESTDIR)$(bindir)) \
+	$(call install_program_targets,$(PKGLIBEXEC_PROGRAMS),$(DESTDIR)$(pkglibexecdir)) \
+	$(call install_program_targets,$(PLUGINS),$(DESTDIR)$(plugindir)) \
+	$(call install_py_plugin_targets,$(PY_PLUGINS),$(DESTDIR)$(plugindir))
+
+install-program: $(INSTALL_PROGRAM_TARGETS)
 	@$(NORMAL_INSTALL)
-	$(INSTALL_PROGRAM) $(BIN_PROGRAMS) $(DESTDIR)$(bindir)
-	$(INSTALL_PROGRAM) $(PKGLIBEXEC_PROGRAMS) $(DESTDIR)$(pkglibexecdir)
-	@if [ -d "$(DESTDIR)$(plugindir)/clnrest" ]; then rm -rf $(DESTDIR)$(plugindir)/clnrest; fi
-	@if [ -d "$(DESTDIR)$(plugindir)/wss-proxy" ]; then rm -rf $(DESTDIR)$(plugindir)/wss-proxy; fi
-	[ -z "$(PLUGINS)" ] || $(INSTALL_PROGRAM) $(PLUGINS) $(DESTDIR)$(plugindir)
-	for PY in $(PY_PLUGINS); do DIR=`dirname $$PY`; DST=$(DESTDIR)$(plugindir)/`basename $$DIR`; if [ -d $$DST ]; then rm -rf $$DST; fi; $(INSTALL_PROGRAM) -d $$DIR; cp -a $$DIR $$DST ; done
 ifeq ($(OS),Darwin)
 	# Install dSYM bundles alongside binaries on macOS
 	for BIN in $(BIN_PROGRAMS); do if [ -d $$BIN.dSYM ]; then cp -a $$BIN.dSYM $(DESTDIR)$(bindir)/; fi; done
@@ -993,13 +1144,15 @@ MAN7PAGES = $(filter %.7,$(MANPAGES))
 MAN8PAGES = $(filter %.8,$(MANPAGES))
 DOC_DATA = README.md LICENSE
 
-install-data: installdirs $(MAN1PAGES) $(MAN5PAGES) $(MAN7PAGES) $(MAN8PAGES) $(DOC_DATA)
+INSTALL_DATA_TARGETS := \
+	$(call install_data_targets,$(MAN1PAGES),$(DESTDIR)$(man1dir)) \
+	$(call install_data_targets,$(MAN5PAGES),$(DESTDIR)$(man5dir)) \
+	$(call install_data_targets,$(MAN7PAGES),$(DESTDIR)$(man7dir)) \
+	$(call install_data_targets,$(MAN8PAGES),$(DESTDIR)$(man8dir)) \
+	$(call install_data_targets,$(DOC_DATA),$(DESTDIR)$(docdir))
+
+install-data: $(INSTALL_DATA_TARGETS)
 	@$(NORMAL_INSTALL)
-	$(INSTALL_DATA) $(MAN1PAGES) $(DESTDIR)$(man1dir)
-	$(INSTALL_DATA) $(MAN5PAGES) $(DESTDIR)$(man5dir)
-	$(INSTALL_DATA) $(MAN7PAGES) $(DESTDIR)$(man7dir)
-	$(INSTALL_DATA) $(MAN8PAGES) $(DESTDIR)$(man8dir)
-	$(INSTALL_DATA) $(DOC_DATA) $(DESTDIR)$(docdir)
 
 install: install-program install-data
 
@@ -1019,44 +1172,21 @@ TESTPACK_EXTRAS :=			\
 testpack.tar.gz: all-programs all-fuzz-programs all-test-programs default-targets
 	(find * -path external -prune -o -path target -prune -o -newer config.vars -type f -print; ls $(TESTPACK_EXTRAS)) | tar --verbatim-files-from -T- -c --format=posix -f - | gzip -5 > $@
 
-uninstall:
+uninstall-program:
 	@$(NORMAL_UNINSTALL)
-	@for f in $(BIN_PROGRAMS); do \
-	  $(ECHO) rm -f $(DESTDIR)$(bindir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(bindir)/`basename $$f`; \
-	done
-	@for f in $(PLUGINS); do \
-	  $(ECHO) rm -f $(DESTDIR)$(plugindir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(plugindir)/`basename $$f`; \
-	done
-	@for f in $(PY_PLUGINS); do \
-	  $(ECHO) rm -rf $(DESTDIR)$(plugindir)/$$(basename $$(dirname $$f)); \
-	  rm -rf $(DESTDIR)$(plugindir)/$$(basename $$(dirname $$f)); \
-	done
-	@for f in $(PKGLIBEXEC_PROGRAMS); do \
-	  $(ECHO) rm -f $(DESTDIR)$(pkglibexecdir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(pkglibexecdir)/`basename $$f`; \
-	done
-	@for f in $(MAN1PAGES); do \
-	  $(ECHO) rm -f $(DESTDIR)$(man1dir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(man1dir)/`basename $$f`; \
-	done
-	@for f in $(MAN5PAGES); do \
-	  $(ECHO) rm -f $(DESTDIR)$(man5dir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(man5dir)/`basename $$f`; \
-	done
-	@for f in $(MAN7PAGES); do \
-	  $(ECHO) rm -f $(DESTDIR)$(man7dir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(man7dir)/`basename $$f`; \
-	done
-	@for f in $(MAN8PAGES); do \
-	  $(ECHO) rm -f $(DESTDIR)$(man8dir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(man8dir)/`basename $$f`; \
-	done
-	@for f in $(DOC_DATA); do \
-	  $(ECHO) rm -f $(DESTDIR)$(docdir)/`basename $$f`; \
-	  rm -f $(DESTDIR)$(docdir)/`basename $$f`; \
-	done
+ifneq ($(strip $(INSTALL_PROGRAM_TARGETS)),)
+	$(RM) -r $(INSTALL_PROGRAM_TARGETS)
+	$(RMDIR_P) $(sort $(dir $(INSTALL_PROGRAM_TARGETS))) 2>/dev/null || :
+endif
+
+uninstall-data:
+	@$(NORMAL_UNINSTALL)
+ifneq ($(strip $(INSTALL_DATA_TARGETS)),)
+	$(RM) -r $(INSTALL_DATA_TARGETS)
+	$(RMDIR_P) $(sort $(dir $(INSTALL_DATA_TARGETS))) 2>/dev/null || :
+endif
+
+uninstall: uninstall-program uninstall-data
 
 installcheck: all-programs
 	@rm -rf testinstall || true
@@ -1072,7 +1202,7 @@ installcheck: all-programs
 version:
 	@echo ${VERSION}
 
-.PHONY: installdirs install-program install-data install uninstall \
+.PHONY: install-program install-data install uninstall-program uninstall-data uninstall \
 	installcheck ncc bin-tarball show-flags version
 
 # Make a tarball of opt/clightning/, optionally with label for distribution.
@@ -1084,114 +1214,6 @@ clightning-$(VERSION)-$(DISTRO).tar.xz: install
 	trap "rm -rf opt" 0; tar cvfa $@ opt/
 endif
 
-ccan-breakpoint.o: $(CCANDIR)/ccan/breakpoint/breakpoint.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-base64.o: $(CCANDIR)/ccan/base64/base64.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-tal.o: $(CCANDIR)/ccan/tal/tal.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-tal-str.o: $(CCANDIR)/ccan/tal/str/str.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-tal-link.o: $(CCANDIR)/ccan/tal/link/link.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-tal-path.o: $(CCANDIR)/ccan/tal/path/path.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-tal-grab_file.o: $(CCANDIR)/ccan/tal/grab_file/grab_file.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-take.o: $(CCANDIR)/ccan/take/take.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-list.o: $(CCANDIR)/ccan/list/list.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-asort.o: $(CCANDIR)/ccan/asort/asort.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-ptr_valid.o: $(CCANDIR)/ccan/ptr_valid/ptr_valid.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-read_write_all.o: $(CCANDIR)/ccan/read_write_all/read_write_all.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-str.o: $(CCANDIR)/ccan/str/str.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-opt.o: $(CCANDIR)/ccan/opt/opt.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-opt-helpers.o: $(CCANDIR)/ccan/opt/helpers.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-opt-parse.o: $(CCANDIR)/ccan/opt/parse.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-opt-usage.o: $(CCANDIR)/ccan/opt/usage.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-err.o: $(CCANDIR)/ccan/err/err.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-noerr.o: $(CCANDIR)/ccan/noerr/noerr.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-str-hex.o: $(CCANDIR)/ccan/str/hex/hex.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crc32c.o: $(CCANDIR)/ccan/crc32c/crc32c.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crypto-hmac.o: $(CCANDIR)/ccan/crypto/hmac_sha256/hmac_sha256.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crypto-hkdf.o: $(CCANDIR)/ccan/crypto/hkdf_sha256/hkdf_sha256.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crypto-shachain.o: $(CCANDIR)/ccan/crypto/shachain/shachain.c
-	@$(call VERBOSE, "cc $< -DSHACHAIN_BITS=48", $(CC) $(CFLAGS) -DSHACHAIN_BITS=48 -c -o $@ $<)
-ccan-crypto-sha256.o: $(CCANDIR)/ccan/crypto/sha256/sha256.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crypto-ripemd160.o: $(CCANDIR)/ccan/crypto/ripemd160/ripemd160.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-cdump.o: $(CCANDIR)/ccan/cdump/cdump.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-strmap.o: $(CCANDIR)/ccan/strmap/strmap.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-strset.o: $(CCANDIR)/ccan/strset/strset.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-crypto-siphash24.o: $(CCANDIR)/ccan/crypto/siphash24/siphash24.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-htable.o: $(CCANDIR)/ccan/htable/htable.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-ilog.o: $(CCANDIR)/ccan/ilog/ilog.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-intmap.o: $(CCANDIR)/ccan/intmap/intmap.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-isaac.o: $(CCANDIR)/ccan/isaac/isaac.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-isaac64.o: $(CCANDIR)/ccan/isaac/isaac64.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-time.o: $(CCANDIR)/ccan/time/time.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-timer.o: $(CCANDIR)/ccan/timer/timer.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-io-io.o: $(CCANDIR)/ccan/io/io.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-io-poll.o: $(CCANDIR)/ccan/io/poll.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-io-fdpass.o: $(CCANDIR)/ccan/io/fdpass/fdpass.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-pipecmd.o: $(CCANDIR)/ccan/pipecmd/pipecmd.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-mem.o: $(CCANDIR)/ccan/mem/mem.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-fdpass.o: $(CCANDIR)/ccan/fdpass/fdpass.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-bitops.o: $(CCANDIR)/ccan/bitops/bitops.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-rbuf.o: $(CCANDIR)/ccan/rbuf/rbuf.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-str-base32.o: $(CCANDIR)/ccan/str/base32/base32.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-utf8.o: $(CCANDIR)/ccan/utf8/utf8.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-bitmap.o: $(CCANDIR)/ccan/bitmap/bitmap.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-membuf.o: $(CCANDIR)/ccan/membuf/membuf.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-json_escape.o: $(CCANDIR)/ccan/json_escape/json_escape.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-json_out.o: $(CCANDIR)/ccan/json_out/json_out.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-closefrom.o: $(CCANDIR)/ccan/closefrom/closefrom.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-rune-rune.o: $(CCANDIR)/ccan/rune/rune.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
-ccan-rune-coding.o: $(CCANDIR)/ccan/rune/coding.c
-	@$(call VERBOSE, "cc $<", $(CC) $(CFLAGS) -c -o $@ $<)
 
 canned-gossmap: devtools/gossmap-compress
 	DATE=`date +%Y-%m-%d` && devtools/gossmap-compress compress --output-node-map /tmp/gossip_store tests/data/gossip-store-$$DATE.compressed > tests/data/gossip-store-$$DATE-node-map && xz -9 tests/data/gossip-store-$$DATE-node-map && ls -l tests/data/gossip-store-$$DATE*
@@ -1201,3 +1223,12 @@ print-binary-sizes: $(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS) $(BIN_PROGRAMS)
 	@size -t $(PKGLIBEXEC_PROGRAMS) $(filter-out tools/reckless,$(BIN_PROGRAMS)) $(PLUGINS)
 	@echo All programs:
 	@size -t $(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS) | tail -n1
+
+.SECONDEXPANSION:
+# All rules beyond this point are subject to secondary expansion of their prerequisites!
+
+$(BUILDDIR)/%.o: %.c | $$(@D)/
+	@$(call VERBOSE,"cc $<",$(COMPILE.c) -o $@ $<)
+
+$(BUILDDIR_FOR_BUILD)/%.o: %.c | $$(@D)/
+	@$(call VERBOSE,"cc $<",$(COMPILE.c) -o $@ $<)
diff --git a/bitcoin/Makefile b/bitcoin/Makefile
index fcf30e9a2f76..d3891cfa036d 100644
--- a/bitcoin/Makefile
+++ b/bitcoin/Makefile
@@ -18,9 +18,10 @@ BITCOIN_SRC :=					\
 	bitcoin/tx_parts.c			\
 	bitcoin/varint.c
 
-BITCOIN_OBJS := $(BITCOIN_SRC:.c=.o)
+BITCOIN_OBJS := $(BITCOIN_SRC:%.c=$(BUILDDIR)/%.o)
 
-BITCOIN_HEADERS := bitcoin/address.h		\
+BITCOIN_HEADERS :=				\
+	bitcoin/address.h			\
 	bitcoin/base58.h			\
 	bitcoin/block.h				\
 	bitcoin/chainparams.h			\
@@ -57,9 +58,7 @@ check-bitcoin-makefile:
 
 check-whitespace: check-whitespace/bitcoin/Makefile
 
-clean: bitcoin-clean
-
-bitcoin-clean:
-	$(RM) $(BITCOIN_OBJS) $(BITCOIN_TEST_PROGRAMS) $(BITCOIN_TEST_OBJS)
+obsclean::
+	$(RM) bitcoin/*.o
 
 include bitcoin/test/Makefile
diff --git a/bitcoin/test/Makefile b/bitcoin/test/Makefile
index eadb3ed3585b..bb4e03f58eab 100644
--- a/bitcoin/test/Makefile
+++ b/bitcoin/test/Makefile
@@ -1,14 +1,17 @@
 BITCOIN_TEST_SRC := $(wildcard bitcoin/test/run-*.c)
-BITCOIN_TEST_OBJS := $(BITCOIN_TEST_SRC:.c=.o)
+BITCOIN_TEST_OBJS := $(BITCOIN_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 BITCOIN_TEST_PROGRAMS := $(BITCOIN_TEST_OBJS:.o=)
 
-$(BITCOIN_TEST_PROGRAMS): bitcoin/chainparams.o libcommon.a
+$(BITCOIN_TEST_PROGRAMS): $(addprefix $(BUILDDIR)/,bitcoin/chainparams.o libcommon.a)
 $(BITCOIN_TEST_OBJS): $(BITCOIN_HEADERS) $(BITCOIN_SRC) bitcoin/test/Makefile
 
 ALL_TEST_PROGRAMS += $(BITCOIN_TEST_PROGRAMS)
 ALL_C_SOURCES += $(BITCOIN_TEST_PROGRAMS:=.c)
 
 # This needs to know what level of optimization we're using.
-bitcoin/test/run-secret_eq_consttime.o: CFLAGS += -DCOPTFLAGS="\"${COPTFLAGS}\""
+$(BUILDDIR)/bitcoin/test/run-secret_eq_consttime.o: CPPFLAGS += -DCOPTFLAGS="\"${COPTFLAGS}\""
 
 check-units: $(BITCOIN_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) bitcoin/test/*.o
diff --git a/ccan/ccan/ptr_valid/ptr_valid.c b/ccan/ccan/ptr_valid/ptr_valid.c
index 7931984023ce..ccde627be8a8 100644
--- a/ccan/ccan/ptr_valid/ptr_valid.c
+++ b/ccan/ccan/ptr_valid/ptr_valid.c
@@ -10,7 +10,7 @@
 #include <assert.h>
 #include <string.h>
 
-#if HAVE_PROC_SELF_MAPS
+#if !defined(HAVE_PROC_SELF_MAPS) || HAVE_PROC_SELF_MAPS
 static char *grab(const char *filename)
 {
 	int ret, fd;
@@ -28,9 +28,10 @@ static char *grab(const char *filename)
 	while ((ret = read(fd, buffer + s, max - s)) > 0) {
 		s += ret;
 		if (s == max) {
-			buffer = realloc(buffer, max*2+1);
-			if (!buffer)
-				goto close;
+			char *nb = realloc(buffer, max*2+1);
+			if (!nb)
+				goto free;
+			buffer = nb;
 			max *= 2;
 		}
 	}
@@ -62,10 +63,14 @@ static struct ptr_valid_map *add_map(struct ptr_valid_map *map,
 				     unsigned long start, unsigned long end, bool is_write)
 {
 	if (*num == *max) {
+		struct ptr_valid_map *newmap;
 		*max *= 2;
-		map = realloc(map, sizeof(*map) * *max);
-		if (!map)
+		newmap = realloc(map, sizeof(*newmap) * *max);
+		if (!newmap) {
+			free(map);
 			return NULL;
+		}
+		map = newmap;
 	}
 	map[*num].start = (void *)start;
 	map[*num].end = (void *)end;
@@ -182,9 +187,9 @@ static void run_child(int infd, int outfd)
 
 		/* This is weird. */
 		if (read(infd, &size, sizeof(size)) != sizeof(size))
-			exit(1);
+			_exit(1);
 		if (read(infd, &is_write, sizeof(is_write)) != sizeof(is_write))
-			exit(2);
+			_exit(2);
 
 		for (i = 0; i < size; i++) {
 			ret = p[i];
@@ -194,9 +199,9 @@ static void run_child(int infd, int outfd)
 
 		/* If we're still here, the answer is "yes". */
 		if (write(outfd, &ret, 1) != 1)
-			exit(3);
+			_exit(3);
 	}
-	exit(0);
+	_exit(0);
 }
 
 static bool create_child(struct ptr_valid_batch *batch)
@@ -271,16 +276,22 @@ bool ptr_valid_batch(struct ptr_valid_batch *batch,
 	char *start, *end;
 	bool ret;
 
-	if ((intptr_t)p & (alignment - 1))
+	if ((intptr_t)p & (alignment - 1)) {
+		errno = EFAULT;
 		return false;
+	}
 
 	start = (void *)((intptr_t)p & ~(getpagesize() - 1));
 	end = (void *)(((intptr_t)p + size - 1) & ~(getpagesize() - 1));
 
 	/* We cache single page hits. */
 	if (start == end) {
-		if (batch->last && batch->last == start)
+		if (batch->last && batch->last == start
+		    && batch->last_write == write) {
+			if (!batch->last_ok)
+				errno = EFAULT;
 			return batch->last_ok;
+		}
 	}
 
 	if (batch->num_maps)
@@ -291,8 +302,11 @@ bool ptr_valid_batch(struct ptr_valid_batch *batch,
 	if (start == end) {
 		batch->last = start;
 		batch->last_ok = ret;
+		batch->last_write = write;
 	}
 
+	if (!ret)
+		errno = EFAULT;
 	return ret;
 }
 
diff --git a/ccan/ccan/ptr_valid/ptr_valid.h b/ccan/ccan/ptr_valid/ptr_valid.h
index 3871cad8e7e4..ad9a2e9c7c3b 100644
--- a/ccan/ccan/ptr_valid/ptr_valid.h
+++ b/ccan/ccan/ptr_valid/ptr_valid.h
@@ -80,6 +80,7 @@ struct ptr_valid_batch {
 	int to_child, from_child;
 	void *last;
 	bool last_ok;
+	bool last_write;
 };
 
 /**
diff --git a/ccan/ccan/ptr_valid/test/run-batch-cache.c b/ccan/ccan/ptr_valid/test/run-batch-cache.c
new file mode 100644
index 000000000000..7f6a9b2bdf8a
--- /dev/null
+++ b/ccan/ccan/ptr_valid/test/run-batch-cache.c
@@ -0,0 +1,41 @@
+/* Regression test: ptr_valid_batch()'s single-page cache ignores the
+ * read/write flag.  On a read-only page, a cached read result makes
+ * ptr_valid_batch_write() claim the page is writable (and a cached
+ * write failure makes ptr_valid_batch_read() claim it is unreadable).
+ * Currently fails: not ok 2 and not ok 4. */
+#include <unistd.h>
+#include <ccan/ptr_valid/ptr_valid.h>
+/* Include the C files directly. */
+#include <ccan/ptr_valid/ptr_valid.c>
+#include <ccan/tap/tap.h>
+#include <sys/mman.h>
+#include <signal.h>
+
+int main(void)
+{
+	char *page;
+	struct ptr_valid_batch batch;
+
+	plan_tests(4);
+	alarm(10);
+
+	page = mmap(NULL, getpagesize(), PROT_READ,
+		    MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	if (page == MAP_FAILED)
+		plan_skip_all("mmap failed");
+
+	/* A cached read hit must not validate a write on the same page. */
+	ptr_valid_batch_start(&batch);
+	ok1(ptr_valid_batch_read(&batch, page));
+	ok1(!ptr_valid_batch_write(&batch, page));
+	ptr_valid_batch_end(&batch);
+
+	/* A cached write miss must not invalidate a read either. */
+	ptr_valid_batch_start(&batch);
+	ok1(!ptr_valid_batch_write(&batch, page));
+	ok1(ptr_valid_batch_read(&batch, page));
+	ptr_valid_batch_end(&batch);
+
+	munmap(page, getpagesize());
+	return exit_status();
+}
diff --git a/ccan/ccan/ptr_valid/test/run-child-flush.c b/ccan/ccan/ptr_valid/test/run-child-flush.c
new file mode 100644
index 000000000000..12507dafc6b1
--- /dev/null
+++ b/ccan/ccan/ptr_valid/test/run-child-flush.c
@@ -0,0 +1,75 @@
+/* Regression test: run_child() exits via exit() instead of _exit(),
+ * so in the no-/proc/self/maps fallback (containers/chroots without
+ * /proc) the child flushes stdio buffers it inherited from the parent
+ * a second time.  We force the fallback by undefining
+ * HAVE_PROC_SELF_MAPS (same code path as /proc being unavailable).
+ * Currently fails: not ok 2. */
+#include <unistd.h>
+#include <ccan/ptr_valid/ptr_valid.h>
+#undef HAVE_PROC_SELF_MAPS
+#define HAVE_PROC_SELF_MAPS 0
+/* Include the C files directly. */
+#include <ccan/ptr_valid/ptr_valid.c>
+#include <ccan/tap/tap.h>
+#include <sys/mman.h>
+#include <signal.h>
+#include <stdio.h>
+
+#if defined(__has_include)
+#if __has_include(<valgrind/valgrind.h>)
+#include <valgrind/valgrind.h>
+#define HAVE_VALGRIND_H 1
+#endif
+#endif
+
+int main(void)
+{
+	char tmpl[] = "/tmp/ptr_valid-flush-XXXXXX";
+	char *page;
+	int fd;
+	FILE *f;
+	long len;
+
+#ifdef HAVE_VALGRIND_H
+	/* valgrind's own child-exit path flushes the inherited buffer,
+	 * masking the module's behavior. */
+	if (RUNNING_ON_VALGRIND) {
+		plan_skip_all("valgrind perturbs stdio across fork");
+		return exit_status();
+	}
+#endif
+
+	plan_tests(2);
+	alarm(10);
+
+	fd = mkstemp(tmpl);
+	if (fd < 0)
+		plan_skip_all("mkstemp failed");
+	f = fdopen(fd, "w");
+	if (!f)
+		plan_skip_all("fdopen failed");
+	unlink(tmpl);
+
+	/* Fully buffered stream with pending data at fork time. */
+	setvbuf(f, NULL, _IOFBF, 4096);
+	fwrite("unflushed-data", 1, 14, f);
+
+	page = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE,
+		    MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	if (page == MAP_FAILED)
+		plan_skip_all("mmap failed");
+
+	/* Creates the probing child; ptr_valid_batch_end() closes the
+	 * pipe, the child sees EOF and calls exit(0), flushing its
+	 * inherited copy of f's buffer. */
+	ok1(ptr_valid_read(page));
+
+	/* The parent now flushes its own copy. */
+	fflush(f);
+	len = ftell(f);
+	fclose(f);
+	munmap(page, getpagesize());
+
+	ok1(len == 14);
+	return exit_status();
+}
diff --git a/ccan/ccan/ptr_valid/test/run-errno.c b/ccan/ccan/ptr_valid/test/run-errno.c
new file mode 100644
index 000000000000..1c2fd4f4f4cd
--- /dev/null
+++ b/ccan/ccan/ptr_valid/test/run-errno.c
@@ -0,0 +1,44 @@
+/* Regression test: ptr_valid.h documents "Sets errno to EFAULT on
+ * failure", but the /proc/self/maps path and the alignment check
+ * return false without setting errno.  Currently fails all 3 tests. */
+#include <unistd.h>
+#include <ccan/ptr_valid/ptr_valid.h>
+/* Include the C files directly. */
+#include <ccan/ptr_valid/ptr_valid.c>
+#include <ccan/tap/tap.h>
+#include <sys/mman.h>
+#include <signal.h>
+#include <errno.h>
+
+int main(void)
+{
+	char *page;
+
+	plan_tests(3);
+	alarm(10);
+
+	page = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE,
+		    MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	if (page == MAP_FAILED)
+		plan_skip_all("mmap failed");
+	munmap(page, getpagesize());
+
+	/* Unmapped pointer (maps path). */
+	errno = 0;
+	ok1(!ptr_valid_read(page) && errno == EFAULT);
+
+	/* Misaligned pointer. */
+	errno = 0;
+	ok1(!ptr_valid(page + 1, getpagesize(), 1, false) && errno == EFAULT);
+
+	/* Read-only page, write check (maps path). */
+	page = mmap(NULL, getpagesize(), PROT_READ,
+		    MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	if (page == MAP_FAILED)
+		plan_skip_all("mmap failed");
+	errno = 0;
+	ok1(!ptr_valid_write(page) && errno == EFAULT);
+	munmap(page, getpagesize());
+
+	return exit_status();
+}
diff --git a/ccan/ccan/ptr_valid/test/run-realloc-leak.c b/ccan/ccan/ptr_valid/test/run-realloc-leak.c
new file mode 100644
index 000000000000..a91a8fe7c232
--- /dev/null
+++ b/ccan/ccan/ptr_valid/test/run-realloc-leak.c
@@ -0,0 +1,131 @@
+/* Regression test: grab() and add_map() overwrite their pointer with
+ * realloc()'s return value, so a failed realloc leaks the old buffer.
+ * We interpose malloc/realloc/free by macro (this file includes
+ * ptr_valid.c directly) and inject a failure at each growth call.
+ * Currently fails: not ok 1 and not ok 2. */
+#include <unistd.h>
+#include <ccan/ptr_valid/ptr_valid.h>
+#include <stdint.h>
+
+static void *live[64];
+static unsigned int nlive;
+static size_t fail_realloc_size;
+
+static void track(void *p)
+{
+	if (p && nlive < sizeof(live)/sizeof(live[0]))
+		live[nlive++] = p;
+}
+
+static void untrack(void *p)
+{
+	unsigned int i;
+
+	for (i = 0; i < nlive; i++) {
+		if (live[i] == p) {
+			live[i] = live[--nlive];
+			return;
+		}
+	}
+}
+
+static void *my_malloc(size_t size)
+{
+	void *p;
+#undef malloc
+	p = malloc(size);
+#define malloc my_malloc
+	track(p);
+	return p;
+}
+
+static void *my_realloc(void *old, size_t size)
+{
+	void *p;
+	uintptr_t o = (uintptr_t)old;
+
+	if (fail_realloc_size && size == fail_realloc_size)
+		return NULL;
+#undef realloc
+	p = realloc(old, size);
+#define realloc my_realloc
+	if (p) {
+		untrack((void *)o);
+		track(p);
+	}
+	return p;
+}
+
+static void my_free(void *p)
+{
+	if (p)
+		untrack(p);
+#undef free
+	free(p);
+#define free my_free
+}
+
+#define malloc my_malloc
+#define realloc my_realloc
+#define free my_free
+/* Include the C files directly. */
+#include <ccan/ptr_valid/ptr_valid.c>
+#undef malloc
+#undef realloc
+#undef free
+
+#include <ccan/tap/tap.h>
+#include <sys/mman.h>
+#include <signal.h>
+
+int main(void)
+{
+	char *region;
+	int i;
+	struct ptr_valid_batch batch;
+
+	alarm(20);
+
+	/* Silence "defined but not used" when ptr_valid.c's
+	 * HAVE_PROC_SELF_MAPS-less build calls no malloc at all. */
+	(void)my_malloc;
+	(void)my_realloc;
+	(void)my_free;
+
+	/* Split a 1000-page mapping into alternating RO/RW VMAs so
+	 * /proc/self/maps exceeds grab()'s initial 16k buffer and has
+	 * more entries than add_map()'s initial 16 slots.
+	 *
+	 * Must resolve this (and plan accordingly) before the single
+	 * plan_tests()/plan_skip_all() call tap allows. */
+	region = mmap(NULL, 1000 * 4096, PROT_READ|PROT_WRITE,
+		      MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	if (region == MAP_FAILED) {
+		plan_skip_all("mmap failed");
+		return exit_status();
+	}
+	for (i = 0; i < 1000; i += 2)
+		if (mprotect(region + i * 4096, 4096, PROT_READ) != 0) {
+			plan_skip_all("mprotect failed");
+			return exit_status();
+		}
+
+	plan_tests(2);
+
+	/* grab(): fail the 16384 -> 32768 buffer growth. */
+	fail_realloc_size = 32768 + 1;
+	nlive = 0;
+	ptr_valid_batch_start(&batch);
+	ptr_valid_batch_end(&batch);
+	ok1(nlive == 0);
+
+	/* add_map(): fail the 16 -> 32 entry array growth. */
+	fail_realloc_size = sizeof(struct ptr_valid_map) * 32;
+	nlive = 0;
+	ptr_valid_batch_start(&batch);
+	ptr_valid_batch_end(&batch);
+	ok1(nlive == 0);
+
+	munmap(region, 1000 * 4096);
+	return exit_status();
+}
diff --git a/ccan/tools/configurator/configurator.c b/ccan/tools/configurator/configurator.c
index 085034fd0eec..e92561b3adf9 100644
--- a/ccan/tools/configurator/configurator.c
+++ b/ccan/tools/configurator/configurator.c
@@ -54,10 +54,12 @@
 #define DEFAULT_FLAGS "-nologo -Zi -W4 -wd4200 " \
 	"-D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS"
 #define DEFAULT_OUTPUT_EXE_FLAG "-Fe:"
+#define DEFAULT_OUTPUT_OBJ_FLAG "-c -Fo:"
 #else
 #define DEFAULT_COMPILER "cc"
 #define DEFAULT_FLAGS "-g3 -ggdb -Wall -Wundef -Wmissing-prototypes -Wmissing-declarations -Wstrict-prototypes -Wold-style-definition"
 #define DEFAULT_OUTPUT_EXE_FLAG "-o"
+#define DEFAULT_OUTPUT_OBJ_FLAG "-c -o"
 #endif
 
 #define OUTPUT_FILE "configurator.out"
@@ -72,28 +74,35 @@
 static const char *progname = "";
 static int verbose;
 static bool like_a_libtool = false;
+static const char *compiler = DEFAULT_COMPILER;
+static const char *flags = DEFAULT_FLAGS;
+static const char *output_exe_flag = DEFAULT_OUTPUT_EXE_FLAG;
+static const char *output_obj_flag = DEFAULT_OUTPUT_OBJ_FLAG;
+static const char *wrapper;
 
 struct test {
 	const char *name;
 	const char *desc;
 	/*
 	 * Template style flags (pick one):
+	 * STATIC_ASSERT:
+	 * - fragment is a compile-time constant expression that must be true.
 	 * OUTSIDE_MAIN:
-	 * - put a simple boilerplate main below it.
+	 * - put a simple boilerplate main() below fragment.
 	 * DEFINES_FUNC:
 	 * - defines a static function called func; adds ref to avoid warnings
 	 * INSIDE_MAIN:
-	 * - put this inside main().
+	 * - put fragment inside main(); implies EXECUTE.
 	 * DEFINES_EVERYTHING:
 	 * - don't add any boilerplate at all.
 	 *
 	 * Execution flags:
 	 * EXECUTE:
-	 * - a runtime test; must compile, exit 0 means flag is set.
+	 * - a runtime test; must compile, link, run, and exit 0 to pass.
 	 * MAY_NOT_COMPILE:
-	 * - Only useful with EXECUTE: don't get upset if it doesn't compile.
+	 * - Only useful with EXECUTE: don't abort if it doesn't compile.
 	 * <nothing>:
-	 * - a compile test, if it compiles must run and exit 0.
+	 * - a compile test; must compile to pass.
 	 */
 	const char *style;
 	const char *depends;
@@ -110,269 +119,243 @@ static struct test *tests;
 
 static const struct test base_tests[] = {
 	{ "HAVE_32BIT_OFF_T", "off_t is 32 bits",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/types.h>\n"
-	  "int main(void) {\n"
-	  "	return sizeof(off_t) == 4 ? 0 : 1;\n"
-	  "}\n" },
+	  "enum { TEST = 1/(sizeof(off_t) == 4) };\n" },
 	{ "HAVE_ALIGNOF", "__alignof__ support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __alignof__(double) > 0 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__alignof__(double) > 0" },
 	{ "HAVE_ASPRINTF", "asprintf() declaration",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#ifndef _GNU_SOURCE\n"
 	  "#define _GNU_SOURCE\n"
 	  "#endif\n"
 	  "#include <stdio.h>\n"
-	  "static char *func(int x) {"
-	  "	char *p;\n"
-	  "	if (asprintf(&p, \"%u\", x) == -1) \n"
-	  "		p = NULL;\n"
-	  "	return p;\n"
-	  "}" },
+	  "int (*func)(char **, const char *, ...) = &asprintf;\n" },
 	{ "HAVE_ATTRIBUTE_COLD", "__attribute__((cold)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static int __attribute__((cold)) func(int x) { return x; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((cold)) func(int);\n" },
 	{ "HAVE_ATTRIBUTE_CONST", "__attribute__((const)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static int __attribute__((const)) func(int x) { return x; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((const)) func(int);\n" },
 	{ "HAVE_ATTRIBUTE_DEPRECATED", "__attribute__((deprecated)) support",
-	  "OUTSIDE_MAIN", NULL, NULL,
-	  "int __attribute__((deprecated)) depr(int x);" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((deprecated)) func(int);\n" },
 	{ "HAVE_ATTRIBUTE_NONNULL", "__attribute__((nonnull)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static char *__attribute__((nonnull)) func(char *p) { return p; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((nonnull)) func(char *);\n" },
 	{ "HAVE_ATTRIBUTE_RETURNS_NONNULL", "__attribute__((returns_nonnull)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static const char *__attribute__((returns_nonnull)) func(void) { return \"hi\"; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "const char * __attribute__((returns_nonnull)) func(void);\n" },
 	{ "HAVE_ATTRIBUTE_SENTINEL", "__attribute__((sentinel)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static int __attribute__((sentinel)) func(int i, ...) { return i; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((sentinel)) func(int, ...);\n" },
 	{ "HAVE_ATTRIBUTE_PURE", "__attribute__((pure)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static int __attribute__((pure)) func(int x) { return x; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((pure)) func(int);\n" },
 	{ "HAVE_ATTRIBUTE_MAY_ALIAS", "__attribute__((may_alias)) support",
-	  "OUTSIDE_MAIN", NULL, NULL,
-	  "typedef short __attribute__((__may_alias__)) short_a;" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "typedef short __attribute__((__may_alias__)) short_a;\n" },
 	{ "HAVE_ATTRIBUTE_NORETURN", "__attribute__((noreturn)) support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "#include <stdlib.h>\n"
-	  "static void __attribute__((noreturn)) func(int x) { exit(x); }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "void __attribute__((noreturn)) func(void);\n" },
 	{ "HAVE_ATTRIBUTE_PRINTF", "__attribute__ format printf support",
-	  "DEFINES_FUNC", NULL, NULL,
-	  "static void __attribute__((format(__printf__, 1, 2))) func(const char *fmt, ...) { (void)fmt; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "void __attribute__((format(__printf__, 1, 2))) func(const char *, ...);\n" },
 	{ "HAVE_ATTRIBUTE_UNUSED", "__attribute__((unused)) support",
-	  "OUTSIDE_MAIN", NULL, NULL,
-	  "static int __attribute__((unused)) func(int x) { return x; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((unused)) func(int);\n" },
 	{ "HAVE_ATTRIBUTE_USED", "__attribute__((used)) support",
-	  "OUTSIDE_MAIN", NULL, NULL,
-	  "static int __attribute__((used)) func(int x) { return x; }" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "int __attribute__((used)) func(int);\n" },
 	{ "HAVE_BACKTRACE", "backtrace() in <execinfo.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <execinfo.h>\n"
-	  "static int func(int x) {"
-	  "	void *bt[10];\n"
-	  "	return backtrace(bt, 10) < x;\n"
-	  "}" },
+	  "int (*func)(void **, int) = &backtrace;\n" },
 	{ "HAVE_BIG_ENDIAN", "big endian",
-	  "INSIDE_MAIN|EXECUTE", NULL, NULL,
+	  "DEFINES_EVERYTHING", "!HAVE_LITTLE_ENDIAN", NULL,
+	  "#if defined(__BYTE_ORDER__)\n"
+	  "	enum { TEST = 1/(__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) };\n"
+	  "#elif defined(__GLIBC__)\n"
+	  "#	include <endian.h>\n"
+	  "	enum { TEST = 1/(__BYTE_ORDER == __BIG_ENDIAN) };\n"
+	  "#elif !defined(_BIG_ENDIAN) && \\\n"
+	  "	!defined(__hppa) && !defined(__hppa__) && \\\n"
+	  "	!defined(__mips) && !defined(__mips__) && \\\n"
+	  "	!defined(_M_PPC) && !defined(__powerpc__) && !defined(__ppc__) && \\\n"
+	  "	!defined(__powerpc64__) && !defined(__ppc64__) && \\\n"
+	  "	!defined(__s390__) && !defined(__s390x__) \\\n"
+	  "	!defined(__sparc) && !defined(__sparc__)\n"
+	  "# error\n"
+	  "#endif\n" },
+	{ "HAVE_BIG_ENDIAN_RUNTIME", "big endian (runtime test)",
+	  "INSIDE_MAIN|EXECUTE", "!HAVE_BIG_ENDIAN !HAVE_LITTLE_ENDIAN", NULL,
 	  "union { int i; char c[sizeof(int)]; } u;\n"
 	  "u.i = 0x01020304;\n"
-	  "return u.c[0] == 0x01 && u.c[1] == 0x02 && u.c[2] == 0x03 && u.c[3] == 0x04 ? 0 : 1;" },
-	{ "HAVE_BSWAP_64", "bswap64 in byteswap.h",
+	  "return u.c[0] == 0x01 && u.c[1] == 0x02 && u.c[2] == 0x03 && u.c[3] == 0x04 ? 0 : 1;",
+	  NULL, "HAVE_BIG_ENDIAN" },
+	{ "HAVE_BSWAP_64", "bswap_64() in <byteswap.h>",
 	  "DEFINES_FUNC", "HAVE_BYTESWAP_H", NULL,
 	  "#include <byteswap.h>\n"
-	  "static int func(int x) { return bswap_64(x); }" },
+	  "static int func(int x) { return bswap_64(x); }\n" },
 	{ "HAVE_BUILTIN_CHOOSE_EXPR", "__builtin_choose_expr support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_choose_expr(1, 0, \"garbage\");" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_choose_expr(1, 0, \"garbage\") == 0" },
 	{ "HAVE_BUILTIN_CLZ", "__builtin_clz support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_clz(1) == (sizeof(int)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_clz(1U)" },
 	{ "HAVE_BUILTIN_CLZL", "__builtin_clzl support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_clzl(1) == (sizeof(long)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_clzl(1UL)" },
 	{ "HAVE_BUILTIN_CLZLL", "__builtin_clzll support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_clzll(1) == (sizeof(long long)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_clzll(1ULL)" },
 	{ "HAVE_BUILTIN_CTZ", "__builtin_ctz support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ctz(1U << (sizeof(int)*8 - 1)) == (sizeof(int)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ctz(1U)" },
 	{ "HAVE_BUILTIN_CTZL", "__builtin_ctzl support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ctzl(1UL << (sizeof(long)*8 - 1)) == (sizeof(long)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ctzl(1UL)" },
 	{ "HAVE_BUILTIN_CTZLL", "__builtin_ctzll support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ctzll(1ULL << (sizeof(long long)*8 - 1)) == (sizeof(long long)*8 - 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ctzll(1ULL)" },
 	{ "HAVE_BUILTIN_CONSTANT_P", "__builtin_constant_p support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_constant_p(1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_constant_p(1)" },
 	{ "HAVE_BUILTIN_EXPECT", "__builtin_expect support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_expect(argc == 1, 1) ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_expect(sizeof(char) == 1, 1)" },
 	{ "HAVE_BUILTIN_FFS", "__builtin_ffs support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ffs(0) == 0 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ffs(0)" },
 	{ "HAVE_BUILTIN_FFSL", "__builtin_ffsl support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ffsl(0L) == 0 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ffsl(0L)" },
 	{ "HAVE_BUILTIN_FFSLL", "__builtin_ffsll support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_ffsll(0LL) == 0 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_ffsll(0LL)" },
 	{ "HAVE_BUILTIN_POPCOUNT", "__builtin_popcount support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_popcount(255) == 8 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_popcount(255U) == 8" },
 	{ "HAVE_BUILTIN_POPCOUNTL",  "__builtin_popcountl support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_popcountl(255L) == 8 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_popcountl(255UL) == 8" },
 	{ "HAVE_BUILTIN_POPCOUNTLL", "__builtin_popcountll support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_popcountll(255LL) == 8 ? 0 : 1;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "__builtin_popcountll(255ULL) == 8" },
 	{ "HAVE_BUILTIN_TYPES_COMPATIBLE_P", "__builtin_types_compatible_p support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return __builtin_types_compatible_p(char *, int) ? 1 : 0;" },
+	  "STATIC_ASSERT", NULL, NULL,
+	  "!__builtin_types_compatible_p(char *, int)" },
 	{ "HAVE_ICCARM_INTRINSICS", "<intrinsics.h>",
 	  "DEFINES_FUNC", NULL, NULL,
 	  "#include <intrinsics.h>\n"
-	  "int func(int v) {\n"
+	  "static int func(int v) {\n"
 	  "	return __CLZ(__RBIT(v));\n"
-	  "}" },
+	  "}\n" },
 	{ "HAVE_BYTESWAP_H", "<byteswap.h>",
-	  "OUTSIDE_MAIN", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <byteswap.h>\n" },
 	{ "HAVE_CLOCK_GETTIME", "clock_gettime() declaration",
-	  "DEFINES_FUNC", "HAVE_STRUCT_TIMESPEC", NULL,
+	  "DEFINES_EVERYTHING", "HAVE_STRUCT_TIMESPEC", NULL,
 	  "#include <time.h>\n"
-	  "static struct timespec func(void) {\n"
-	  "	struct timespec ts;\n"
-	  "	clock_gettime(CLOCK_REALTIME, &ts);\n"
-	  "	return ts;\n"
-	  "}\n" },
+	  "int (*func)(clockid_t, struct timespec *) = &clock_gettime;\n" },
 	{ "HAVE_CLOCK_GETTIME_IN_LIBRT", "clock_gettime() in librt",
-	  "DEFINES_FUNC",
+	  "DEFINES_EVERYTHING",
 	  "HAVE_STRUCT_TIMESPEC !HAVE_CLOCK_GETTIME",
 	  "-lrt",
 	  "#include <time.h>\n"
-	  "static struct timespec func(void) {\n"
-	  "	struct timespec ts;\n"
-	  "	clock_gettime(CLOCK_REALTIME, &ts);\n"
-	  "	return ts;\n"
-	  "}\n",
+	  "int (*func)(clockid_t, struct timespec *) = &clock_gettime;\n",
 	  /* This means HAVE_CLOCK_GETTIME, too */
-	  "HAVE_CLOCK_GETTIME" },
+	  NULL, "HAVE_CLOCK_GETTIME" },
 	{ "HAVE_COMPOUND_LITERALS", "compound literal support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "int *foo = (int[]) { 1, 2, 3, 4 };\n"
-	  "return foo[0] ? 0 : 1;" },
-	{ "HAVE_FCHDIR", "fchdir support",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE", NULL, NULL,
-	  "#include <sys/types.h>\n"
-	  "#include <sys/stat.h>\n"
-	  "#include <fcntl.h>\n"
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "const int *foo = (int[]) { 1, 2, 3, 4 };\n" },
+	{ "HAVE_FCHDIR", "fchdir() declaration",
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <unistd.h>\n"
-	  "int main(void) {\n"
-	  "	int fd = open(\"..\", O_RDONLY);\n"
-	  "	return fchdir(fd) == 0 ? 0 : 1;\n"
-	  "}\n" },
+	  "int (*func)(int) = &fchdir;\n" },
 	{ "HAVE_ERR_H", "<err.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <err.h>\n"
-	  "static void func(int arg) {\n"
-	  "	if (arg == 0)\n"
-	  "		err(1, \"err %u\", arg);\n"
-	  "	if (arg == 1)\n"
-	  "		errx(1, \"err %u\", arg);\n"
-	  "	if (arg == 3)\n"
-	  "		warn(\"warn %u\", arg);\n"
-	  "	if (arg == 4)\n"
-	  "		warnx(\"warn %u\", arg);\n"
-	  "}\n" },
+	  "void (*func0)(int, const char *, ...) = &err;\n"
+	  "void (*func1)(int, const char *, ...) = &errx;\n"
+	  "void (*func2)(const char *, ...) = &warn;\n"
+	  "void (*func3)(const char *, ...) = &warnx;\n" },
 	{ "HAVE_FILE_OFFSET_BITS", "_FILE_OFFSET_BITS to get 64-bit offsets",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE",
-	  "HAVE_32BIT_OFF_T", NULL,
+	  "DEFINES_EVERYTHING", "HAVE_32BIT_OFF_T", NULL,
 	  "#define _FILE_OFFSET_BITS 64\n"
 	  "#include <sys/types.h>\n"
-	  "int main(void) {\n"
-	  "	return sizeof(off_t) == 8 ? 0 : 1;\n"
-	  "}\n" },
+	  "enum { TEST = 1/(sizeof(off_t) == 8) };\n" },
 	{ "HAVE_FOR_LOOP_DECLARATION", "for loop declaration support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "int ret = 1;\n"
-	  "for (int i = 0; i < argc; i++) { ret = 0; };\n"
-	  "return ret;" },
+	  "DEFINES_FUNC", NULL, NULL,
+	  "static void func(void) { for (int i = 0; i < 1; ++i); }\n" },
 	{ "HAVE_FLEXIBLE_ARRAY_MEMBER", "flexible array member support",
-	  "OUTSIDE_MAIN", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "struct foo { unsigned int x; int arr[]; };" },
 	{ "HAVE_GETPAGESIZE", "getpagesize() in <unistd.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <unistd.h>\n"
-	  "static int func(void) { return getpagesize(); }" },
+	  "int (*func)(void) = &getpagesize;\n" },
 	{ "HAVE_ISBLANK", "isblank() in <ctype.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#ifndef _GNU_SOURCE\n"
 	  "#define _GNU_SOURCE\n"
 	  "#endif\n"
 	  "#include <ctype.h>\n"
-	  "static int func(void) { return isblank(' '); }" },
+	  "int (*func)(int) = &isblank;\n" },
 	{ "HAVE_LITTLE_ENDIAN", "little endian",
-	  "INSIDE_MAIN|EXECUTE", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "#if defined(__BYTE_ORDER__)\n"
+	  "	enum { TEST = 1/(__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) };\n"
+	  "#elif defined(__GLIBC__)\n"
+	  "#	include <endian.h>\n"
+	  "	enum { TEST = 1/(__BYTE_ORDER == __LITTLE_ENDIAN) };\n"
+	  "#elif !defined(_LITTLE_ENDIAN) && \\\n"
+	  "	!defined(_M_ALPHA) && !defined(__alpha) && !defined(__alpha__) && \\\n"
+	  "	!defined(_M_AMD64) && !defined(__amd64) && !defined(__amd64__) && \\\n"
+	  "	!defined(_M_ARM) && !defined(__arm) && !defined(__arm__) && \\\n"
+	  "	!defined(_M_ARM64) && !defined(__aarch64) && !defined(__aarch64__) && \\\n"
+	  "	!defined(_M_IA64) && !defined(__ia64) && !defined(__ia64__) && \\\n"
+	  "	!defined(_M_IX86) && !defined(__i386) && !defined(__i386__) && \\\n"
+	  "	!defined(_M_X64) && !defined(__x86_64) && !defined(__x86_64__) && \\\n"
+	  "	!defined(__bfin) && !defined(__bfin__)\n"
+	  "# error\n"
+	  "#endif\n" },
+	{ "HAVE_LITTLE_ENDIAN_RUNTIME", "little endian (runtime test)",
+	  "INSIDE_MAIN|EXECUTE", "!HAVE_BIG_ENDIAN !HAVE_LITTLE_ENDIAN", NULL,
 	  "union { int i; char c[sizeof(int)]; } u;\n"
 	  "u.i = 0x01020304;\n"
-	  "return u.c[0] == 0x04 && u.c[1] == 0x03 && u.c[2] == 0x02 && u.c[3] == 0x01 ? 0 : 1;" },
-	{ "HAVE_MEMMEM", "memmem in <string.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "return u.c[0] == 0x04 && u.c[1] == 0x03 && u.c[2] == 0x02 && u.c[3] == 0x01 ? 0 : 1;",
+	  NULL, "HAVE_LITTLE_ENDIAN" },
+	{ "HAVE_MEMMEM", "memmem() in <string.h>",
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#ifndef _GNU_SOURCE\n"
 	  "#define _GNU_SOURCE\n"
 	  "#endif\n"
 	  "#include <string.h>\n"
-	  "static void *func(void *h, size_t hl, void *n, size_t nl) {\n"
-	  "return memmem(h, hl, n, nl);"
-	  "}\n", },
-	{ "HAVE_MEMRCHR", "memrchr in <string.h>",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "void * (*func)(const void *, size_t, const void *, size_t) = &memmem;\n" },
+	{ "HAVE_MEMRCHR", "memrchr() in <string.h>",
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#ifndef _GNU_SOURCE\n"
 	  "#define _GNU_SOURCE\n"
 	  "#endif\n"
 	  "#include <string.h>\n"
-	  "static void *func(void *s, int c, size_t n) {\n"
-	  "return memrchr(s, c, n);"
-	  "}\n", },
+	  "void * (*func)(const void *, int, size_t) = &memrchr;\n" },
 	{ "HAVE_MMAP", "mmap() declaration",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/mman.h>\n"
-	  "static void *func(int fd) {\n"
-	  "	return mmap(0, 65536, PROT_READ, MAP_SHARED, fd, 0);\n"
-	  "}" },
-	{ "HAVE_PROC_SELF_MAPS", "/proc/self/maps exists",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE", NULL, NULL,
-	  "#include <sys/types.h>\n"
-	  "#include <sys/stat.h>\n"
-	  "#include <fcntl.h>\n"
-	  "int main(void) {\n"
-	  "	return open(\"/proc/self/maps\", O_RDONLY) != -1 ? 0 : 1;\n"
-	  "}\n" },
+	  "void * (*func)(void *, size_t, int, int, int, off_t) = &mmap;\n" },
 	{ "HAVE_QSORT_R_PRIVATE_LAST", "qsort_r cmp takes trailing arg",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#ifndef _GNU_SOURCE\n"
 	  "#define _GNU_SOURCE\n"
 	  "#endif\n"
 	  "#include <stdlib.h>\n"
-	  "static int cmp(const void *lp, const void *rp, void *priv) {\n"
-	  " *(unsigned int *)priv = 1;\n"
-	  " return *(const int *)lp - *(const int *)rp; }\n"
-	  "int main(void) {\n"
-	  " int array[] = { 9, 2, 5 };\n"
-	  " unsigned int called = 0;\n"
-	  " qsort_r(array, 3, sizeof(int), cmp, &called);\n"
-	  " return called && array[0] == 2 && array[1] == 5 && array[2] == 9 ? 0 : 1;\n"
-	  "}\n" },
+	  "void (*func)(void *, size_t, size_t, int (*)(const void *, const void *, void *), void *) = &qsort_r;\n" },
 	{ "HAVE_STRUCT_TIMESPEC", "struct timespec declaration",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <time.h>\n"
-	  "static void func(void) {\n"
-	  "	struct timespec ts;\n"
-	  "	ts.tv_sec = ts.tv_nsec = 1;\n"
-	  "}\n" },
+	  "const struct timespec ts = { .tv_sec = 1, .tv_nsec = 1 };\n" },
 	{ "HAVE_SECTION_START_STOP", "__attribute__((section)) and __start/__stop",
 	  "DEFINES_FUNC", NULL, NULL,
 	  "static void *__attribute__((__section__(\"mysec\"))) p = &p;\n"
@@ -381,35 +364,53 @@ static const struct test base_tests[] = {
 	  "	return __stop_mysec - __start_mysec;\n"
 	  "}\n" },
 	{ "HAVE_STACK_GROWS_UPWARDS", "stack grows upwards",
-	  "DEFINES_EVERYTHING|EXECUTE", NULL, NULL,
-	  "#include <stddef.h>\n"
-	  "static ptrdiff_t nest(const void *base, unsigned int i)\n"
-	  "{\n"
-	  "	if (i == 0)\n"
-	  "		return (const char *)&i - (const char *)base;\n"
-	  "	return nest(base, i-1);\n"
-	  "}\n"
-	  "int main(int argc, char *argv[]) {\n"
-	  "	(void)argv;\n"
-	  "	return (nest(&argc, argc) > 0) ? 0 : 1;\n"
-	  "}\n" },
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "#if !defined(__hppa)\n"
+	  "# error\n"
+	  "#endif\n" },
 	{ "HAVE_STATEMENT_EXPR", "statement expression support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "return ({ int x = argc; x == argc ? 0 : 1; });" },
+	  "DEFINES_FUNC", NULL, NULL,
+	  "static int func(void) { return ({ int x = 0; x == 0 ? 0 : 1; }); }\n" },
+	{ "HAVE_STATIC_ASSERT", "_Static_assert support",
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "_Static_assert(1, \"OK\");\n" },
 	{ "HAVE_SYS_FILIO_H", "<sys/filio.h>",
-	  "OUTSIDE_MAIN", NULL, NULL, /* Solaris needs this for FIONREAD */
+	  "DEFINES_EVERYTHING", NULL, NULL, /* Solaris needs this for FIONREAD */
 	  "#include <sys/filio.h>\n" },
 	{ "HAVE_SYS_TERMIOS_H", "<sys/termios.h>",
-	  "OUTSIDE_MAIN", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/termios.h>\n" },
 	{ "HAVE_SYS_UNISTD_H", "<sys/unistd.h>",
-	  "OUTSIDE_MAIN", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/unistd.h>\n" },
 	{ "HAVE_TYPEOF", "__typeof__ support",
-	  "INSIDE_MAIN", NULL, NULL,
-	  "__typeof__(argc) i; i = argc; return i == argc ? 0 : 1;" },
-	{ "HAVE_UNALIGNED_ACCESS", "unaligned access to int",
-	  "DEFINES_EVERYTHING|EXECUTE", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "static int i;\n"
+	  "__typeof__(i) *p = &i;\n" },
+	{ "HAVE_EFFICIENT_UNALIGNED_ACCESS", "efficient unaligned memory access",
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "#if !defined(_M_AMD64) && !defined(__amd64) && !defined(__amd64__) && \\\n"
+	  "	!defined(__ARM_FEATURE_UNALIGNED) && \\\n"
+	  "	!defined(_M_ARM64) && !defined(__aarch64) && !defined(__aarch64__) && \\\n"
+	  "	!defined(_M_IX86) && !defined(__i386) && !defined(__i386__) && \\\n"
+	  "	!defined(_M_PPC) && !defined(__powerpc__) && !defined(__ppc__) && \\\n"
+	  "	!defined(__powerpc64__) && !defined(__ppc64__) && \\\n"
+	  "	!defined(__s390__) && !defined(__s390x__) \\\n"
+	  "	!defined(_M_X64) && !defined(__x86_64) && !defined(__x86_64__)\n"
+	  "# error\n"
+	  "#endif\n",
+	  NULL, "HAVE_UNALIGNED_ACCESS" },
+	{ "HAVE_NO_UNALIGNED_ACCESS", "known lack of unaligned memory access",
+	  "DEFINES_EVERYTHING", "!HAVE_EFFICIENT_UNALIGNED_ACCESS", NULL,
+	  "#if !defined(_M_ALPHA) && !defined(__alpha) && !defined(__alpha__) && \\\n"
+	  "	(!defined(_M_ARM) && !defined(__arm) && !defined(__arm__) || defined(__ARM_FEATURE_UNALIGNED)) && \\\n"
+	  "	!defined(__hppa) && !defined(__hppa__) && \\\n"
+	  "	!defined(__mips) && !defined(__mips__) && \\\n"
+	  "	!defined(__sparc) && !defined(__sparc__)\n"
+	  "# error\n"
+	  "#endif\n" },
+	{ "HAVE_UNALIGNED_ACCESS", "unaligned memory access (runtime test)",
+	  "DEFINES_EVERYTHING|EXECUTE", "!HAVE_NO_UNALIGNED_ACCESS", NULL,
 	  "#include <string.h>\n"
 	  "int main(int argc, char *argv[]) {\n"
 	  "	(void)argc;\n"
@@ -419,52 +420,33 @@ static const struct test base_tests[] = {
 	  "	return *x == *y;\n"
 	  "}\n" },
 	{ "HAVE_UTIME", "utime() declaration",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/types.h>\n"
 	  "#include <utime.h>\n"
-	  "static int func(const char *filename) {\n"
-	  "	struct utimbuf times = { 0 };\n"
-	  "	return utime(filename, &times);\n"
-	  "}" },
+	  "int (*func)(const char *, const struct utimbuf *) = &utime;\n" },
 	{ "HAVE_WARN_UNUSED_RESULT", "__attribute__((warn_unused_result))",
-	  "DEFINES_FUNC", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <sys/types.h>\n"
 	  "#include <utime.h>\n"
-	  "static __attribute__((warn_unused_result)) int func(int i) {\n"
-	  "	return i + 1;\n"
-	  "}" },
+	  "__attribute__((warn_unused_result)) int func(void);\n" },
 	{ "HAVE_OPENMP", "#pragma omp and -fopenmp support",
-	  "INSIDE_MAIN|EXECUTE|MAY_NOT_COMPILE", NULL, NULL,
-	  "int i;\n"
+	  "DEFINES_FUNC", NULL, NULL,
+	  "static void func(void) {\n"
+	  "	int i;\n"
 	  "#pragma omp parallel for\n"
-	  "for(i = 0; i < 0; i++) {};\n"
-	  "return 0;\n",
+	  "	for(i = 0; i < 0; ++i);\n"
+	  "}\n",
 	  "-Werror -fopenmp" },
 	{ "HAVE_VALGRIND_MEMCHECK_H", "<valgrind/memcheck.h>",
-	  "OUTSIDE_MAIN", NULL, NULL,
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <valgrind/memcheck.h>\n" },
-	{ "HAVE_UCONTEXT", "working <ucontext.h",
-	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE",
-	  NULL, NULL,
+	{ "HAVE_UCONTEXT", "<ucontext.h>",
+	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <ucontext.h>\n"
-	  "static int x = 0;\n"
-	  "static char stack[2048];\n"
-	  "static ucontext_t a, b;\n"
-	  "static void fn(void) {\n"
-	  "	x |= 2;\n"
-	  "	setcontext(&b);\n"
-	  "	x |= 4;\n"
-	  "}\n"
-	  "int main(void) {\n"
-	  "	x |= 1;\n"
-	  "	getcontext(&a);\n"
-	  "	a.uc_stack.ss_sp = stack;\n"
-	  "	a.uc_stack.ss_size = sizeof(stack);\n"
-	  "	makecontext(&a, fn, 0);\n"
-	  "	swapcontext(&b, &a);\n"
-	  "	return (x == 3) ? 0 : 1;\n"
-	  "}\n"
-	},
+	  "int (*func0)(ucontext_t *) = &getcontext;\n"
+	  "int (*func1)(const ucontext_t *) = &setcontext;\n"
+	  "void (*func2)(ucontext_t *, void (*)(void), int, ...) = &makecontext;\n"
+	  "int (*func3)(ucontext_t *, const ucontext_t *) = &swapcontext;\n" },
 	{ "HAVE_POINTER_SAFE_MAKECONTEXT", "passing pointers via makecontext()",
 	  "DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE",
 	  "HAVE_UCONTEXT", NULL,
@@ -491,50 +473,36 @@ static const struct test base_tests[] = {
 	  "	return worked ? 0 : 1;\n"
 	  "}\n"
 	},
-	{ "HAVE_BUILTIN_CPU_SUPPORTS", "__builtin_cpu_supports()",
+	{ "HAVE_BUILTIN_CPU_SUPPORTS", "__builtin_cpu_supports support",
 	  "DEFINES_FUNC", NULL, NULL,
-	  "#include <stdbool.h>\n"
-	  "static bool func(void) {\n"
-	  "	return __builtin_cpu_supports(\"mmx\");\n"
-	  "}"
-	},
-	{ "HAVE_CLOSEFROM", "closefrom() offered by system",
+	  "static int func(void) { return __builtin_cpu_supports(\"mmx\"); }\n" },
+	{ "HAVE_CLOSEFROM", "closefrom() declaration",
 	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <stdlib.h>\n"
 	  "#include <unistd.h>\n"
-	  "int main(void) {\n"
-	  "    closefrom(STDERR_FILENO + 1);\n"
-	  "    return 0;\n"
-	  "}\n"
-	},
-	{ "HAVE_F_CLOSEM", "F_CLOSEM defined for fctnl.",
+	  "void (*func)(int) = &closefrom;\n" },
+	{ "HAVE_F_CLOSEM", "F_CLOSEM",
 	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <fcntl.h>\n"
 	  "#include <unistd.h>\n"
-	  "int main(void) {\n"
-	  "    int res = fcntl(STDERR_FILENO + 1, F_CLOSEM, 0);\n"
-	  "    return res < 0;\n"
-	  "}\n"
-	},
-	{ "HAVE_NR_CLOSE_RANGE", "close_range syscall available as __NR_close_range.",
+	  "enum { TEST = F_CLOSEM };\n" },
+	{ "HAVE_CLOSE_RANGE", "close_range() declaration",
+	  "DEFINES_EVERYTHING", NULL, NULL,
+	  "#ifndef _GNU_SOURCE\n"
+	  "#define _GNU_SOURCE\n"
+	  "#endif\n"
+	  "#include <unistd.h>\n"
+	  "int (*func)(unsigned, unsigned, int) = &close_range;\n" },
+	{ "HAVE_NR_CLOSE_RANGE", "__NR_close_range",
 	  "DEFINES_EVERYTHING", NULL, NULL,
-	  "#include <limits.h>\n"
 	  "#include <sys/syscall.h>\n"
 	  "#include <unistd.h>\n"
-	  "int main(void) {\n"
-	  "    int res = syscall(__NR_close_range, STDERR_FILENO + 1, INT_MAX, 0);\n"
-	  "    return res < 0;\n"
-	  "}\n"
-	},
-	{ "HAVE_F_MAXFD", "F_MAXFD defined for fcntl.",
+	  "enum { TEST = __NR_close_range };\n" },
+	{ "HAVE_F_MAXFD", "F_MAXFD",
 	  "DEFINES_EVERYTHING", NULL, NULL,
 	  "#include <fcntl.h>\n"
 	  "#include <unistd.h>\n"
-	  "int main(void) {\n"
-	  "    int res = fcntl(0, F_MAXFD);\n"
-	  "    return res < 0;\n"
-	  "}\n"
-	},
+	  "int test = F_MAXFD;\n" },
 };
 
 static void c12r_err(int eval, const char *fmt, ...)
@@ -558,7 +526,7 @@ static void c12r_errx(int eval, const char *fmt, ...)
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+	fputc('\n', stderr);
 	exit(eval);
 }
 
@@ -573,7 +541,7 @@ static void start_test(const char *what, const char *why)
 static void end_test(bool result)
 {
 	if (like_a_libtool)
-		printf("%s\n", result ? "yes" : "no");
+		puts(result ? "yes" : "no");
 }
 
 static size_t fcopy(FILE *fsrc, FILE *fdst)
@@ -634,27 +602,43 @@ static char *run(const char *cmd, int *exitstatus)
 	return ret;
 }
 
-static char *connect_args(const char *argv[], const char *outflag,
-		const char *files)
+/*
+ * Efficiently joins together an arbitrary number of strings using a glue char.
+ * The returned string must be freed when it is no longer needed.
+ * Each variadic argument is a pointer to an array of pointers to strings.
+ * The last element in each array must be NULL.
+ * The last argument must be NULL.
+ */
+static char *concat(int glue, /* (const char *const *) */...)
 {
-	unsigned int i;
-	char *ret;
-	size_t len = strlen(outflag) + strlen(files) + 1;
-
-	for (i = 1; argv[i]; i++)
-		len += 1 + strlen(argv[i]);
-
-	ret = malloc(len);
-	len = 0;
-	for (i = 1; argv[i]; i++) {
-		strcpy(ret + len, argv[i]);
-		len += strlen(argv[i]);
-		if (argv[i+1] || *outflag)
-			ret[len++] = ' ';
+	va_list ap;
+	size_t len = 0;
+	const char *const *arg;
+	const char *s;
+	char *ret, *p;
+
+	va_start(ap, glue);
+	while ((arg = va_arg(ap, const char *const *))) {
+		while ((s = *arg++)) {
+			size_t n = strlen(s);
+			len += n + !!n;
+		}
 	}
-	strcpy(ret + len, outflag);
-	len += strlen(outflag);
-	strcpy(ret + len, files);
+	va_end(ap);
+	if (!len)
+		return strdup("");
+
+	p = ret = malloc(len);
+	va_start(ap, glue);
+	while ((arg = va_arg(ap, const char *const *))) {
+		while ((s = *arg++)) {
+			p = stpcpy(p, s);
+			*p++ = (char) glue;
+		}
+	}
+	va_end(ap);
+	*--p = '\0';
+
 	return ret;
 }
 
@@ -671,6 +655,8 @@ static struct test *find_test(const char *name)
 }
 
 #define PRE_BOILERPLATE "/* Test program generated by configurator. */\n"
+#define STATIC_ASSERT_START_BOILERPLATE "enum { TEST = 1/!!("
+#define STATIC_ASSERT_END_BOILERPLATE ") };\n"
 #define MAIN_START_BOILERPLATE \
 	"int main(int argc, char *argv[]) {\n" \
 	"	(void)argc;\n" \
@@ -679,10 +665,11 @@ static struct test *find_test(const char *name)
 #define MAIN_BODY_BOILERPLATE "return 0;\n"
 #define MAIN_END_BOILERPLATE "}\n"
 
-static bool run_test(const char *cmd, const char *wrapper, struct test *test)
+static bool run_test(struct test *test)
 {
 	char *output, *newcmd;
 	FILE *outf;
+	const char *args[4], **arg = args;
 	int status;
 
 	if (test->done)
@@ -691,58 +678,56 @@ static bool run_test(const char *cmd, const char *wrapper, struct test *test)
 	if (test->depends) {
 		size_t len;
 		const char *deps = test->depends;
-		char *dep;
+		const char *dep;
 
 		/* Space-separated dependencies, could be ! for inverse. */
-		while ((len = strcspn(deps, " ")) != 0) {
-			bool positive = true;
-			if (deps[len]) {
-				dep = strdup(deps);
-				dep[len] = '\0';
-			} else {
-				dep = (char *)deps;
-			}
-
-			if (dep[0] == '!') {
-				dep++;
-				positive = false;
-			}
-			if (run_test(cmd, wrapper, find_test(dep)) != positive) {
+		while ((len = strcspn(deps += strspn(deps, " "), " ")) != 0) {
+			bool positive = deps[0] != '!';
+			if (!positive)
+				++deps, --len;
+			dep = deps[len] ? strndup(deps, len) : deps;
+			if (run_test(find_test(dep)) != positive) {
 				test->answer = false;
 				test->done = true;
 				return test->answer;
 			}
 			if (deps[len])
-				free(dep);
-
+				free((void *) dep);
 			deps += len;
-			deps += strspn(deps, " ");
 		}
 	}
 
+	bool need_run = strstr(test->style, "EXECUTE");
+
 	outf = fopen(INPUT_FILE, verbose > 1 ? "w+" : "w");
 	if (!outf)
 		c12r_err(EXIT_TROUBLE_RUNNING, "creating %s", INPUT_FILE);
 
-	fprintf(outf, "%s", PRE_BOILERPLATE);
+	fputs(PRE_BOILERPLATE, outf);
 
-	if (strstr(test->style, "INSIDE_MAIN")) {
-		fprintf(outf, "%s", MAIN_START_BOILERPLATE);
-		fprintf(outf, "%s", test->fragment);
-		fprintf(outf, "%s", MAIN_END_BOILERPLATE);
+	if (strstr(test->style, "STATIC_ASSERT")) {
+		fputs(STATIC_ASSERT_START_BOILERPLATE, outf);
+		fputs(test->fragment, outf);
+		fputs(STATIC_ASSERT_END_BOILERPLATE, outf);
+	} else if (strstr(test->style, "INSIDE_MAIN")) {
+		fputs(MAIN_START_BOILERPLATE, outf);
+		fputs(test->fragment, outf);
+		fputs(MAIN_END_BOILERPLATE, outf);
+		/* We run INSIDE_MAIN tests for sanity checking. */
+		need_run = true;
 	} else if (strstr(test->style, "OUTSIDE_MAIN")) {
-		fprintf(outf, "%s", test->fragment);
-		fprintf(outf, "%s", MAIN_START_BOILERPLATE);
-		fprintf(outf, "%s", MAIN_BODY_BOILERPLATE);
-		fprintf(outf, "%s", MAIN_END_BOILERPLATE);
+		fputs(test->fragment, outf);
+		fputs(MAIN_START_BOILERPLATE, outf);
+		fputs(MAIN_BODY_BOILERPLATE, outf);
+		fputs(MAIN_END_BOILERPLATE, outf);
 	} else if (strstr(test->style, "DEFINES_FUNC")) {
-		fprintf(outf, "%s", test->fragment);
-		fprintf(outf, "%s", MAIN_START_BOILERPLATE);
-		fprintf(outf, "%s", USE_FUNC_BOILERPLATE);
-		fprintf(outf, "%s", MAIN_BODY_BOILERPLATE);
-		fprintf(outf, "%s", MAIN_END_BOILERPLATE);
+		fputs(test->fragment, outf);
+		fputs(MAIN_START_BOILERPLATE, outf);
+		fputs(USE_FUNC_BOILERPLATE, outf);
+		fputs(MAIN_BODY_BOILERPLATE, outf);
+		fputs(MAIN_END_BOILERPLATE, outf);
 	} else if (strstr(test->style, "DEFINES_EVERYTHING")) {
-		fprintf(outf, "%s", test->fragment);
+		fputs(test->fragment, outf);
 	} else
 		c12r_errx(EXIT_BAD_TEST, "Unknown style for test %s: %s",
 			  test->name, test->style);
@@ -754,26 +739,28 @@ static bool run_test(const char *cmd, const char *wrapper, struct test *test)
 
 	fclose(outf);
 
-	newcmd = strdup(cmd);
-
 	if (test->flags) {
-		newcmd = realloc(newcmd, strlen(newcmd) + strlen(" ")
-				+ strlen(test->flags) + 1);
-		strcat(newcmd, " ");
-		strcat(newcmd, test->flags);
+		*arg++ = test->flags;
 		if (verbose > 1)
-			printf("Extra flags line: %s", newcmd);
+			printf("Extra compiler flags: %s\n", test->flags);
 	}
 
 	if (test->link) {
-		newcmd = realloc(newcmd, strlen(newcmd) + strlen(" ")
-				+ strlen(test->link) + 1);
-		strcat(newcmd, " ");
-		strcat(newcmd, test->link);
+		*arg++ = test->link;
 		if (verbose > 1)
-			printf("Extra link line: %s", newcmd);
+			printf("Extra linker flags: %s\n", test->link);
+		*arg++ = output_exe_flag;
+	} else if (need_run) {
+		*arg++ = output_exe_flag;
+	} else {
+		*arg++ = output_obj_flag;
 	}
 
+	*arg = NULL;
+	newcmd = concat(' ', (const char *[]) { compiler, flags, NULL }, args,
+			(const char *[]) { OUTPUT_FILE, INPUT_FILE, NULL },
+			NULL);
+
 	start_test("checking for ", test->desc);
 	output = run(newcmd, &status);
 
@@ -795,14 +782,17 @@ static bool run_test(const char *cmd, const char *wrapper, struct test *test)
 		/* Compile succeeded. */
 		free(output);
 		/* We run INSIDE_MAIN tests for sanity checking. */
-		if (strstr(test->style, "EXECUTE")
-		    || strstr(test->style, "INSIDE_MAIN")) {
-			char *runcmd = malloc(strlen(wrapper) + strlen(" ." DIR_SEP OUTPUT_FILE) + 1);
-
-			strcpy(runcmd, wrapper);
-			strcat(runcmd, " ." DIR_SEP OUTPUT_FILE);
-			output = run(runcmd, &status);
-			free(runcmd);
+		if (need_run) {
+			if (wrapper) {
+				char *runcmd = malloc(strlen(wrapper) +
+					strlen(" ." DIR_SEP OUTPUT_FILE) + 1);
+				strcpy(stpcpy(runcmd, wrapper),
+				       " ." DIR_SEP OUTPUT_FILE);
+				output = run(runcmd, &status);
+				free(runcmd);
+			} else {
+				output = run("." DIR_SEP OUTPUT_FILE, &status);
+			}
 			if (!strstr(test->style, "EXECUTE") && status != 0)
 				c12r_errx(EXIT_BAD_TEST,
 					  "Test for %s failed with %i:\n%s",
@@ -874,7 +864,7 @@ static char *read_field(const char *name, bool compulsory)
  * First three non-ignored lines must be:
  *  var=<varname>
  *  desc=<description-for-autotools-style>
- *  style=OUTSIDE_MAIN DEFINES_FUNC INSIDE_MAIN DEFINES_EVERYTHING EXECUTE MAY_NOT_COMPILE
+ *  style=STATIC_ASSERT OUTSIDE_MAIN DEFINES_FUNC INSIDE_MAIN DEFINES_EVERYTHING EXECUTE MAY_NOT_COMPILE
  *
  * Followed by optional lines:
  *  depends=<space-separated-testnames, ! to invert>
@@ -947,13 +937,8 @@ static void read_tests(size_t num_tests)
 
 int main(int argc, const char *argv[])
 {
-	char *cmd;
 	unsigned int i;
-	const char *default_args[]
-		= { "", DEFAULT_COMPILER, DEFAULT_FLAGS, NULL };
-	const char *outflag = DEFAULT_OUTPUT_EXE_FLAG;
 	const char *configurator_cc = NULL;
-	const char *wrapper = "";
 	const char *orig_cc;
 	const char *varfile = NULL;
 	const char *headerfile = NULL;
@@ -961,70 +946,61 @@ int main(int argc, const char *argv[])
 	FILE *outf;
 
 	if (argc > 0)
-		progname = argv[0];
+		progname = *argv++, --argc;
 
-	while (argc > 1) {
-		if (strcmp(argv[1], "--help") == 0) {
-			printf("Usage: configurator [-v] [--var-file=<filename>] [-O<outflag>] [--configurator-cc=<compiler-for-tests>] [--wrapper=<wrapper-for-tests>] [--autotools-style] [--extra-tests] [<compiler> <flags>...]\n"
+	for (; argc > 0; ++argv, --argc) {
+		if (strcmp(argv[0], "--help") == 0) {
+			printf("Usage: configurator [-v] [--var-file=<filename>] [--output-exe=<outflag>] [--output-obj=<outflag>] [--configurator-cc=<compiler-for-tests>] [--wrapper=<wrapper-for-tests>] [--autotools-style] [--extra-tests] [<compiler> <flags>...]\n"
 			       "  <compiler> <flags> will have \"<outflag> <outfile> <infile.c>\" appended\n"
-			       "Default: %s %s %s\n",
+			       "Default <compiler> <flags>: %s %s\n"
+			       "Default --output-exe=\"%s\"\n"
+			       "Default --output-obj=\"%s\"\n",
 			       DEFAULT_COMPILER, DEFAULT_FLAGS,
-			       DEFAULT_OUTPUT_EXE_FLAG);
+			       DEFAULT_OUTPUT_EXE_FLAG,
+			       DEFAULT_OUTPUT_OBJ_FLAG);
 			exit(0);
 		}
-		if (strncmp(argv[1], "-O", 2) == 0) {
-			argc--;
-			argv++;
-			outflag = argv[1] + 2;
-			if (!*outflag) {
+		if (strncmp(argv[0], "-O", 2) == 0) { /* legacy compatibility */
+			if (!argv[0][2]) {
 				fprintf(stderr,
 					"%s: option requires an argument -- O\n",
 					argv[0]);
 				exit(EXIT_BAD_USAGE);
 			}
-		} else if (strcmp(argv[1], "-v") == 0) {
-			argc--;
-			argv++;
+			output_exe_flag = argv[0] + 2;
+		} else if (strcmp(argv[0], "-v") == 0) {
 			verbose++;
-		} else if (strcmp(argv[1], "-vv") == 0) {
-			argc--;
-			argv++;
+		} else if (strcmp(argv[0], "-vv") == 0) {
 			verbose += 2;
-		} else if (strncmp(argv[1], "--configurator-cc=", 18) == 0) {
-			configurator_cc = argv[1] + 18;
-			argc--;
-			argv++;
-		} else if (strncmp(argv[1], "--wrapper=", 10) == 0) {
-			wrapper = argv[1] + 10;
-			argc--;
-			argv++;
-		} else if (strncmp(argv[1], "--var-file=", 11) == 0) {
-			varfile = argv[1] + 11;
-			argc--;
-			argv++;
-		} else if (strcmp(argv[1], "--autotools-style") == 0) {
+		} else if (strncmp(argv[0], "--output-exe=", 13) == 0) {
+			output_exe_flag = argv[0] + 13;
+		} else if (strncmp(argv[0], "--output-obj=", 13) == 0) {
+			output_obj_flag = argv[0] + 13;
+		} else if (strncmp(argv[0], "--configurator-cc=", 18) == 0) {
+			configurator_cc = argv[0] + 18;
+		} else if (strncmp(argv[0], "--wrapper=", 10) == 0) {
+			wrapper = argv[0] + 10;
+		} else if (strncmp(argv[0], "--var-file=", 11) == 0) {
+			varfile = argv[0] + 11;
+		} else if (strcmp(argv[0], "--autotools-style") == 0) {
 			like_a_libtool = true;
-			argc--;
-			argv++;
-		} else if (strncmp(argv[1], "--header-file=", 14) == 0) {
-			headerfile = argv[1] + 14;
-			argc--;
-			argv++;
-		} else if (strcmp(argv[1], "--extra-tests") == 0) {
+		} else if (strncmp(argv[0], "--header-file=", 14) == 0) {
+			headerfile = argv[0] + 14;
+		} else if (strcmp(argv[0], "--extra-tests") == 0) {
 			extra_tests = true;
-			argc--;
-			argv++;
-		} else if (strcmp(argv[1], "--") == 0) {
+		} else if (strcmp(argv[0], "--") == 0) {
 			break;
-		} else if (argv[1][0] == '-') {
-			c12r_errx(EXIT_BAD_USAGE, "Unknown option %s", argv[1]);
+		} else if (argv[0][0] == '-') {
+			c12r_errx(EXIT_BAD_USAGE, "Unknown option %s", argv[0]);
 		} else {
 			break;
 		}
 	}
 
-	if (argc == 1)
-		argv = default_args;
+	if (argc > 0)
+		compiler = *argv++, --argc;
+	if (argc > 0)
+		flags = concat(' ', argv, NULL);
 
 	/* Copy with NULL entry at end */
 	tests = calloc(sizeof(base_tests)/sizeof(base_tests[0]) + 1,
@@ -1034,19 +1010,17 @@ int main(int argc, const char *argv[])
 	if (extra_tests)
 		read_tests(sizeof(base_tests)/sizeof(base_tests[0]));
 
-	orig_cc = argv[1];
+	orig_cc = compiler;
 	if (configurator_cc)
-		argv[1] = configurator_cc;
+		compiler = configurator_cc;
 
-	cmd = connect_args(argv, outflag, OUTPUT_FILE " " INPUT_FILE);
 	if (like_a_libtool) {
 		start_test("Making autoconf users comfortable", "");
 		sleep(1);
 		end_test(1);
 	}
 	for (i = 0; tests[i].name; i++)
-		run_test(cmd, wrapper, &tests[i]);
-	free(cmd);
+		run_test(&tests[i]);
 
 	remove(OUTPUT_FILE);
 	remove(INPUT_FILE);
@@ -1082,22 +1056,21 @@ int main(int argc, const char *argv[])
 	} else
 		outf = stdout;
 
-	fprintf(outf, "/* Generated by CCAN configurator */\n"
-	       "#ifndef CCAN_CONFIG_H\n"
-	       "#define CCAN_CONFIG_H\n");
-	fprintf(outf, "#ifndef _GNU_SOURCE\n");
-	fprintf(outf, "#define _GNU_SOURCE /* Always use GNU extensions. */\n");
-	fprintf(outf, "#endif\n");
+	fputs("/* Generated by CCAN configurator */\n"
+	      "#ifndef CCAN_CONFIG_H\n"
+	      "#define CCAN_CONFIG_H\n"
+	      "#ifndef _GNU_SOURCE\n"
+	      "#define _GNU_SOURCE /* Always use GNU extensions. */\n"
+	      "#endif\n", outf);
 	fprintf(outf, "#define CCAN_COMPILER \"%s\"\n", orig_cc);
-	cmd = connect_args(argv + 1, "", "");
-	fprintf(outf, "#define CCAN_CFLAGS \"%s\"\n", cmd);
-	free(cmd);
-	fprintf(outf, "#define CCAN_OUTPUT_EXE_CFLAG \"%s\"\n\n", outflag);
+	fprintf(outf, "#define CCAN_CFLAGS \"%s\"\n", flags);
+	fprintf(outf, "#define CCAN_OUTPUT_EXE_CFLAG \"%s\"\n\n", output_exe_flag);
+	fprintf(outf, "#define CCAN_OUTPUT_OBJ_CFLAG \"%s\"\n\n", output_obj_flag);
 	/* This one implies "#include <ccan/..." works, eg. for tdb2.h */
-	fprintf(outf, "#define HAVE_CCAN 1\n");
+	fputs("#define HAVE_CCAN 1\n", outf);
 	for (i = 0; tests[i].name; i++)
 		fprintf(outf, "#define %s %u\n", tests[i].name, tests[i].answer);
-	fprintf(outf, "#endif /* CCAN_CONFIG_H */\n");
+	fputs("#endif /* CCAN_CONFIG_H */\n", outf);
 
 	if (headerfile) {
 		if (fclose(outf) != 0)
diff --git a/channeld/Makefile b/channeld/Makefile
index a2c11e8bdda7..6c08b32362f5 100644
--- a/channeld/Makefile
+++ b/channeld/Makefile
@@ -18,25 +18,30 @@ CHANNELD_SRC := channeld/channeld.c	\
 	channeld/channeld_wiregen.c		\
 	channeld/watchtower.c
 
-CHANNELD_OBJS := $(CHANNELD_SRC:.c=.o)
+CHANNELD_OBJS := $(CHANNELD_SRC:%.c=$(BUILDDIR)/%.o)
 $(CHANNELD_OBJS): $(CHANNELD_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(CHANNELD_SRC)
 ALL_C_HEADERS += $(CHANNELD_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_channeld
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightning_channeld
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += \
 	channeld/channeld_wiregen.h \
 	channeld/inflight.h
-LIGHTNINGD_CONTROL_OBJS +=  \
+LIGHTNINGD_CONTROL_OBJS += \
+	$(addprefix $(BUILDDIR)/, \
 	channeld/channeld_wiregen.o \
-	channeld/inflight.o
+	channeld/inflight.o \
+	)
 
-channeld/full_channel_error_names_gen.h: channeld/full_channel_error.h ccan/ccan/cdump/tools/cdump-enumstr
-	ccan/ccan/cdump/tools/cdump-enumstr channeld/full_channel_error.h > $@
+channeld/full_channel_error_names_gen.h: channeld/full_channel_error.h $(CDUMP_ENUMSTR)
+	$(CDUMP_ENUMSTR) channeld/full_channel_error.h > $@
 
-lightningd/lightning_channeld: $(CHANNELD_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_channeld: $(CHANNELD_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) channeld/*.o
 
 include channeld/test/Makefile
diff --git a/channeld/test/Makefile b/channeld/test/Makefile
index f683ec31b26f..0a5c45382246 100644
--- a/channeld/test/Makefile
+++ b/channeld/test/Makefile
@@ -1,17 +1,18 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 CHANNELD_TEST_SRC := $(wildcard channeld/test/run-*.c)
-CHANNELD_TEST_OBJS := $(CHANNELD_TEST_SRC:.c=.o)
+CHANNELD_TEST_OBJS := $(CHANNELD_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 CHANNELD_TEST_PROGRAMS := $(CHANNELD_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(CHANNELD_TEST_SRC)
 ALL_TEST_PROGRAMS += $(CHANNELD_TEST_PROGRAMS)
 
 # run-full_channel.o needs a special version of some common files!
-$(filter-out channeld/test/run-full_channel,$(CHANNELD_TEST_PROGRAMS)): libcommon.a
+$(filter-out channeld/test/run-full_channel,$(CHANNELD_TEST_PROGRAMS)): $(BUILDDIR)/libcommon.a
 
-channeld/test/run-full_channel:			\
+$(BUILDDIR)/channeld/test/run-full_channel:	\
 	$(BITCOIN_OBJS)				\
+	$(addprefix $(BUILDDIR)/,		\
 	wire/towire.o				\
 	wire/fromwire.o				\
 	common/amount.o				\
@@ -29,8 +30,12 @@ channeld/test/run-full_channel:			\
 	common/pseudorand.o			\
 	common/randbytes.o			\
 	common/setup.o				\
-	common/utils.o
+	common/utils.o				\
+	)
 
 $(CHANNELD_TEST_OBJS): $(CHANNELD_HEADERS) $(CHANNELD_SRC) channeld/test/Makefile
 
+obsclean::
+	$(RM) channeld/test/*.o
+
 check-units: $(CHANNELD_TEST_PROGRAMS:%=unittest/%)
diff --git a/cli/Makefile b/cli/Makefile
index 4839e5138344..473f4f6fee94 100644
--- a/cli/Makefile
+++ b/cli/Makefile
@@ -1,12 +1,15 @@
 LIGHTNING_CLI_SRC := cli/lightning-cli.c
-LIGHTNING_CLI_OBJS := $(LIGHTNING_CLI_SRC:.c=.o)
+LIGHTNING_CLI_OBJS := $(LIGHTNING_CLI_SRC:%.c=$(BUILDDIR)/%.o)
 
 ALL_C_SOURCES += $(LIGHTNING_CLI_SRC)
 ALL_C_HEADERS +=
-ALL_PROGRAMS += cli/lightning-cli
+ALL_PROGRAMS += $(BUILDDIR)/cli/lightning-cli
 
 $(LIGHTNING_CLI_OBJS): cli/Makefile
 
-cli/lightning-cli: $(LIGHTNING_CLI_OBJS) libcommon.a
+$(BUILDDIR)/cli/lightning-cli: $(LIGHTNING_CLI_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) cli/*.o
 
 include cli/test/Makefile
diff --git a/cli/test/Makefile b/cli/test/Makefile
index d6dcffb787ce..079b5a6698d1 100644
--- a/cli/test/Makefile
+++ b/cli/test/Makefile
@@ -1,14 +1,17 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 CLI_TEST_SRC := $(wildcard cli/test/run-*.c)
-CLI_TEST_OBJS := $(CLI_TEST_SRC:.c=.o)
+CLI_TEST_OBJS := $(CLI_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 CLI_TEST_PROGRAMS := $(CLI_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(CLI_TEST_SRC)
 ALL_TEST_PROGRAMS += $(CLI_TEST_PROGRAMS)
 
-$(CLI_TEST_PROGRAMS): libcommon.a
+$(CLI_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 
 $(CLI_TEST_OBJS): $(LIGHTNING_CLI_HEADERS) $(LIGHTNING_CLI_SRC) cli/test/Makefile
 
 check-units: $(CLI_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) cli/test/*.o
diff --git a/closingd/Makefile b/closingd/Makefile
index a128163f2756..9eabb0a61280 100644
--- a/closingd/Makefile
+++ b/closingd/Makefile
@@ -5,7 +5,7 @@ CLOSINGD_HEADERS := closingd/closingd_wiregen.h
 CLOSINGD_SRC := closingd/closingd.c	\
 	$(CLOSINGD_HEADERS:.h=.c)
 
-CLOSINGD_OBJS := $(CLOSINGD_SRC:.c=.o)
+CLOSINGD_OBJS := $(CLOSINGD_SRC:%.c=$(BUILDDIR)/%.o)
 $(CLOSINGD_OBJS): $(CLOSINGD_HEADERS)
 
 # Simple close daemon
@@ -14,20 +14,23 @@ SIMPLECLOSED_HEADERS := closingd/simpleclosed_wiregen.h
 SIMPLECLOSED_SRC := closingd/simpleclosed.c	\
 	$(SIMPLECLOSED_HEADERS:.h=.c)
 
-SIMPLECLOSED_OBJS := $(SIMPLECLOSED_SRC:.c=.o)
+SIMPLECLOSED_OBJS := $(SIMPLECLOSED_SRC:%.c=$(BUILDDIR)/%.o)
 $(SIMPLECLOSED_OBJS): $(SIMPLECLOSED_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(CLOSINGD_SRC) $(SIMPLECLOSED_SRC)
 ALL_C_HEADERS += $(CLOSINGD_HEADERS) $(SIMPLECLOSED_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_closingd lightningd/lightning_simpleclosed
+ALL_PROGRAMS += $(addprefix $(BUILDDIR)/lightningd/,lightning_closingd lightning_simpleclosed)
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += closingd/closingd_wiregen.h closingd/simpleclosed_wiregen.h
-LIGHTNINGD_CONTROL_OBJS += closingd/closingd_wiregen.o closingd/simpleclosed_wiregen.o
+LIGHTNINGD_CONTROL_OBJS += $(addprefix $(BUILDDIR)/closingd/,closingd_wiregen.o simpleclosed_wiregen.o)
 
-lightningd/lightning_closingd: $(CLOSINGD_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_closingd: $(CLOSINGD_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
 
-lightningd/lightning_simpleclosed: $(SIMPLECLOSED_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_simpleclosed: $(SIMPLECLOSED_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) closingd/*.o
 
 -include closingd/test/Makefile
diff --git a/common/Makefile b/common/Makefile
index d60606420807..7fa4a87b8bea 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -132,7 +132,7 @@ COMMON_HEADERS_GEN := common/htlc_state_names_gen.h common/status_wiregen.h comm
 COMMON_HEADERS := $(COMMON_HEADERS_GEN) $(COMMON_HEADERS_NOGEN)
 COMMON_SRC := $(COMMON_SRC_NOGEN) $(COMMON_SRC_GEN)
 
-COMMON_OBJS := $(COMMON_SRC:.c=.o)
+COMMON_OBJS := $(COMMON_SRC:%.c=$(BUILDDIR)/%.o)
 
 common/scb_wiregen.h_args := -s
 common/scb_wiregen.c_args := -s
@@ -145,28 +145,29 @@ check-common-files:
 check-source: check-common-files
 
 # Only common/version.c can include this header.
-common/version.o: version_gen.h
+$(BUILDDIR)/common/version.o: version_gen.h
 
 # Rebuild objects should this file change.
 $(COMMON_OBJS): common/Makefile
 
 # We make a static library, this way linker can discard unused parts.
-libcommon.a: $(COMMON_OBJS) $(WIRE_OBJS) $(BITCOIN_OBJS)
-	@$(call VERBOSE, "ar $@", $(AR) r $@ $?)
+$(BUILDDIR)/libcommon.a: $(BUILDDIR)/libcommon.a($(COMMON_OBJS) $(WIRE_OBJS) $(BITCOIN_OBJS))
 
 ALL_C_HEADERS += $(COMMON_HEADERS)
 ALL_C_SOURCES += $(COMMON_SRC)
 
-common/htlc_state_names_gen.h: common/htlc_state.h ccan/ccan/cdump/tools/cdump-enumstr
-	ccan/ccan/cdump/tools/cdump-enumstr common/htlc_state.h > $@
+common/htlc_state_names_gen.h: common/htlc_state.h $(CDUMP_ENUMSTR)
+	$(CDUMP_ENUMSTR) common/htlc_state.h > $@
 
 check-source-bolt: $(COMMON_SRC_NOGEN:%=bolt-check/%) $(COMMON_HEADERS_NOGEN:%=bolt-check/%)
 check-whitespace: $(COMMON_SRC_NOGEN:%=check-whitespace/%) $(COMMON_HEADERS_NOGEN:%=check-whitespace/%)
 
 clean: common-clean
 
+obsclean::
+	$(RM) libcommon.a common/*.o
+
 common-clean:
-	$(RM) libcommon.a
 	$(RM) common/gen*
 
 include common/test/Makefile
diff --git a/common/test/Makefile b/common/test/Makefile
index 71f9dc17d981..9588a5726c06 100644
--- a/common/test/Makefile
+++ b/common/test/Makefile
@@ -1,14 +1,16 @@
 COMMON_TEST_SRC := $(wildcard common/test/run-*.c)
 
-COMMON_TEST_OBJS := $(COMMON_TEST_SRC:.c=.o)
+COMMON_TEST_OBJS := $(COMMON_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 COMMON_TEST_PROGRAMS := $(COMMON_TEST_OBJS:.o=)
 
 COMMON_TEST_COMMON_OBJS :=				\
+	$(addprefix $(BUILDDIR)/, 			\
 	common/autodata.o				\
 	common/randbytes.o				\
 	common/clock_time.o				\
 	common/setup.o					\
-	common/utils.o
+	common/utils.o					\
+	)
 
 $(COMMON_TEST_PROGRAMS): $(COMMON_TEST_COMMON_OBJS) $(BITCOIN_OBJS)
 $(COMMON_TEST_OBJS): $(COMMON_HEADERS) $(WIRE_HEADERS) $(COMMON_SRC) common/test/Makefile
@@ -20,13 +22,14 @@ ALL_TEST_PROGRAMS += $(COMMON_TEST_PROGRAMS)
 $(COMMON_TEST_OBJS): $(COMMON_SRC)
 
 # Sphinx test wants to decode TLVs.
-common/test/run-sphinx: wire/onion_wiregen.o wire/towire.o wire/fromwire.o
-common/test/run-blindedpath_enctlv common/test/run-blindedpath_onion: common/base32.o common/wireaddr.o wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o
-common/test/run-route_blinding_test: wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o common/coin_mvt.o
-common/test/run-route_blinding_override_test: common/base32.o common/wireaddr.o wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o common/coin_mvt.o
-
-common/test/run-param					\
-common/test/run-json:					\
+$(BUILDDIR)/common/test/run-sphinx: $(addprefix $(BUILDDIR)/,wire/onion_wiregen.o wire/towire.o wire/fromwire.o)
+$(BUILDDIR)/common/test/run-blindedpath_enctlv $(BUILDDIR)/common/test/run-blindedpath_onion: $(addprefix $(BUILDDIR)/,common/base32.o common/wireaddr.o wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o)
+$(BUILDDIR)/common/test/run-route_blinding_test: $(addprefix $(BUILDDIR)/,wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o common/coin_mvt.o)
+$(BUILDDIR)/common/test/run-route_blinding_override_test: $(addprefix $(BUILDDIR)/,common/base32.o common/wireaddr.o wire/onion_wiregen.o wire/peer_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o common/coin_mvt.o)
+
+$(BUILDDIR)/common/test/run-param			\
+$(BUILDDIR)/common/test/run-json:			\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/base32.o					\
 	common/bigsize.o				\
@@ -41,9 +44,13 @@ common/test/run-json:					\
 	wire/fromwire.o					\
 	wire/onion_wiregen.o				\
 	wire/peer_wiregen.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-route common/test/run-route-specific common/test/run-route-infloop:	\
+$(BUILDDIR)/common/test/run-route			\
+$(BUILDDIR)/common/test/run-route-specific		\
+$(BUILDDIR)/common/test/run-route-infloop:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/dijkstra.o				\
 	common/fp16.o					\
@@ -55,25 +62,31 @@ common/test/run-route common/test/run-route-specific common/test/run-route-inflo
         common/gossip_store_wiregen.o			\
 	wire/fromwire.o					\
 	wire/peer_wiregen.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-gossmap_local:				\
+$(BUILDDIR)/common/test/run-gossmap_local:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/base32.o					\
 	common/wireaddr.o				\
 	wire/fromwire.o					\
 	wire/peer_wiregen.o				\
 	wire/tlvstream.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-gossmap_canned:				\
+$(BUILDDIR)/common/test/run-gossmap_canned:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/base32.o					\
 	common/wireaddr.o				\
 	wire/fromwire.o					\
 	wire/peer_wiregen.o				\
 	wire/tlvstream.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-bolt12_merkle:				\
+$(BUILDDIR)/common/test/run-bolt12_merkle:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/bigsize.o				\
 	common/base32.o					\
@@ -86,9 +99,11 @@ common/test/run-bolt12_merkle:				\
 	wire/fromwire.o					\
 	wire/tlvstream.o				\
 	wire/peer_wiregen.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-bolt12_merkle-partial:			\
+$(BUILDDIR)/common/test/run-bolt12_merkle-partial:	\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/bigsize.o				\
 	common/base32.o					\
@@ -101,9 +116,11 @@ common/test/run-bolt12_merkle-partial:			\
 	wire/fromwire.o					\
 	wire/tlvstream.o				\
 	wire/peer_wiregen.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-bolt12-format-string-test:		\
+$(BUILDDIR)/common/test/run-bolt12-format-string-test:	\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/bigsize.o				\
 	common/base32.o					\
@@ -113,13 +130,18 @@ common/test/run-bolt12-format-string-test:		\
 	common/node_id.o				\
 	wire/bolt12_wiregen.o				\
 	wire/tlvstream.o				\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-bolt12_merkle-json:			\
+$(BUILDDIR)/common/test/run-bolt12_merkle-json:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/base32.o					\
-	common/wireaddr.o
+	common/wireaddr.o				\
+	)
 
-common/test/run-bolt12_proof common/test/run-bolt12_proof_vectors: \
+$(BUILDDIR)/common/test/run-bolt12_proof		\
+$(BUILDDIR)/common/test/run-bolt12_proof_vectors:	\
+	$(addprefix $(BUILDDIR)/,			\
 	common/bolt12.o					\
 	common/bigsize.o				\
 	common/amount.o					\
@@ -128,15 +150,19 @@ common/test/run-bolt12_proof common/test/run-bolt12_proof_vectors: \
 	wire/onion_wiregen.o				\
 	wire/tlvstream.o				\
 	wire/fromwire.o					\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-version:				\
+$(BUILDDIR)/common/test/run-version:			\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o                                 \
 	wire/fromwire.o					\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
 
-common/test/run-splice_script:				\
+$(BUILDDIR)/common/test/run-splice_script:		\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/node_id.o				\
 	common/bech32.o					\
@@ -144,38 +170,61 @@ common/test/run-splice_script:				\
 	common/wireaddr.o				\
 	common/base32.o					\
 	wire/fromwire.o					\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
 
-common/test/run-trace:					\
+$(BUILDDIR)/common/test/run-trace:			\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o                                 \
 	common/memleak.o				\
 	common/pseudorand.o				\
 	common/randbytes.o				\
 	common/trace.o					\
 	wire/fromwire.o					\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
-common/test/run-mkdatastorekey:				\
-	common/pseudorand.o
+$(BUILDDIR)/common/test/run-mkdatastorekey:		\
+	$(addprefix $(BUILDDIR)/,			\
+	common/pseudorand.o				\
+	)
 
-common/test/run-htable:					\
+$(BUILDDIR)/common/test/run-htable:			\
+	$(addprefix $(BUILDDIR)/,			\
 	common/randbytes.o				\
-	common/pseudorand.o
+	common/pseudorand.o				\
+	)
 
-common/test/run-shutdown_scriptpubkey: wire/towire.o wire/fromwire.o
+$(BUILDDIR)/common/test/run-shutdown_scriptpubkey:	\
+	$(addprefix $(BUILDDIR)/,			\
+	wire/towire.o					\
+	wire/fromwire.o					\
+	)
 
-common/test/run-wireaddr: wire/towire.o wire/fromwire.o
+$(BUILDDIR)/common/test/run-wireaddr:			\
+	$(addprefix $(BUILDDIR)/,			\
+	wire/towire.o					\
+	wire/fromwire.o					\
+	)
 
-common/test/run-jsonrpc_io: common/json_parse_simple.o
+$(BUILDDIR)/common/test/run-jsonrpc_io:			\
+	$(addprefix $(BUILDDIR)/,			\
+	common/json_parse_simple.o			\
+	)
 
-common/test/run-close_tx:			\
+$(BUILDDIR)/common/test/run-close_tx:			\
+	$(addprefix $(BUILDDIR)/,			\
 	common/amount.o					\
 	common/close_tx.o				\
 	common/permute_tx.o				\
 	common/psbt_keypath.o			\
 	common/pseudorand.o				\
 	wire/fromwire.o					\
-	wire/towire.o
+	wire/towire.o					\
+	)
 
 check-units: $(COMMON_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) common/test/*.o
diff --git a/common/test/run-close_tx.c b/common/test/run-close_tx.c
index 42a1cea40f76..f5196d0817ac 100644
--- a/common/test/run-close_tx.c
+++ b/common/test/run-close_tx.c
@@ -7,7 +7,7 @@
 #include <common/close_tx.h>
 #include <common/setup.h>
 #include <common/utils.h>
-#include <external/libwally-core/include/wally_script.h>
+#include <wally_script.h>
 #include <stdio.h>
 
 static void test_create_simple_close_tx_basic(void)
diff --git a/configure b/configure
index 0cd88749dc92..c7c80db031ea 100755
--- a/configure
+++ b/configure
@@ -20,14 +20,19 @@ LIBRARY_PATH=/usr/local/lib
 export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/usr/local/opt/sqlite/lib/pkgconfig
 fi
 
-: ${PKG_CONFIG=pkg-config}
-
-# You can set PG_CONFIG in the environment to direct configure to call
-# a specific 'pg_config' binary. If you set it to an empty string, then
-# PostgreSQL support will be explicitly disabled, even if a 'pg_config'
-# binary exists in your PATH. If you leave it unset, then the following
-# line enables the automagic detection that most users want.
-: ${PG_CONFIG=pg_config}
+: "${PKG_CONFIG=pkg-config}"
+
+# You can set PG_CONFIG in the environment to direct configure to call a
+# specific 'pg_config' binary. If you set it to an empty string, then automagic
+# detection of PostgreSQL will be explicitly disabled even if a 'pg_config'
+# binary exists in your PATH. However, fallback detection will still happen.
+# You can disable PostgreSQL support entirely by setting POSTGRES_LDLIBS to an
+# empty string, or you can set POSTGRES_INCLUDE and POSTGRES_LDLIBS (which
+# specify options to pass to the C preprocessor and linker respectively) to
+# attempt to build against a specific PostgreSQL installation. If you leave
+# all three variables unset, then the following line enables the automagic
+# detection that most users want.
+: "${PG_CONFIG=pg_config}"
 
 usage_with_default()
 {
@@ -134,12 +139,12 @@ check_command()
     name="$1"
     shift 1
 
-    echo -n "checking for $name... "
+    printf 'checking for %s... ' "${name}" >&2
     if "$@" >/dev/null 2>&1 </dev/null; then
-	echo 'found'
+	echo 'found' >&2
 	return 0
     fi
-    echo 'not found'
+    echo 'not found' >&2
     return 1
 }
 
@@ -169,11 +174,15 @@ set_defaults()
     # Note that ":-" means substitute if empty or unset, "-" means only if unset
     # which matters since you might explicitly set of these blank.
     PREFIX=${PREFIX:-/usr/local}
-    CC=${CC:-cc}
+    # A more compact way of setting the default value of a variable.
+    # Similar to the above, ":=" means assign if empty or unset; "=" means assign only if unset.
+    # The quotes suppress the globbing that would otherwise occur after variable expansion.
+    : "${CC:=${HOST:+$HOST-}cc}"
+    : "${CPPFLAGS=-std=gnu11}"
             # Detect macOS and use appropriate debug flags for libbacktrace compatibility
     if [ "$(uname -s)" = "Darwin" ]; then
         # Always override to avoid DWARF 5
-        CDEBUGFLAGS="-std=gnu11 -g -gdwarf-4 -fno-standalone-debug -fstack-protector-strong"
+        CDEBUGFLAGS="-g -gdwarf-4 -fno-standalone-debug -fstack-protector-strong"
         # Set SDKROOT for macOS
         SDKROOT="$(xcrun --sdk macosx --show-sdk-path)"
 
@@ -182,7 +191,7 @@ set_defaults()
             echo "Warning: dsymutil not found. Install Xcode Command Line Tools for better debug support."
         fi
     else
-        CDEBUGFLAGS=${CDEBUGFLAGS--std=gnu11 -g -fstack-protector-strong}
+        CDEBUGFLAGS=${CDEBUGFLAGS--g -fstack-protector-strong}
     fi
     DEBUGBUILD=${DEBUGBUILD:-0}
     COMPAT=${COMPAT:-1}
@@ -211,6 +220,17 @@ set_defaults()
     PYTEST=${PYTEST-$(default_pytest $PYTHON)}
     COPTFLAGS=${COPTFLAGS-$(default_coptflags "$DEBUGBUILD")}
     CONFIGURATOR_CC=${CONFIGURATOR_CC-$CC}
+    if [ "x$BUILD" = "x$HOST" ]; then
+	: "${CC_FOR_BUILD:=$CC}"
+	: "${CFLAGS_FOR_BUILD=$CFLAGS}"
+	: "${CPPFLAGS_FOR_BUILD=$CPPFLAGS}"
+	: "${LDFLAGS_FOR_BUILD=$LDFLAGS}"
+    else
+	: "${CC_FOR_BUILD:=${BUILD:+$BUILD-}cc}"
+	: "${CFLAGS_FOR_BUILD=-O1}"
+	: "${CPPFLAGS_FOR_BUILD=-std=gnu11}"
+	: "${LDFLAGS_FOR_BUILD=}"
+    fi
     VALGRIND=${VALGRIND:-$(default_valgrind_setting)}
     TEST_NETWORK=${TEST_NETWORK:-regtest}
     RUST=${RUST:-$(default_rust_setting)}
@@ -223,7 +243,7 @@ have_function_sections()
     TMPCFILE=$CONFIG_VAR_FILE.$$.c
     TMPOBJFILE=$CONFIG_VAR_FILE.$$.o
     
-    echo "int foo(void); int foo(void) { return 0; }" > $TMPCFILE
+    echo "int main(void); int main(void) { return 0; }" > $TMPCFILE
     # We *want* this to fail if we get a warning, hence use -Werror.
     $1 $2 -Werror -ffunction-sections -Wl,--gc-sections $TMPCFILE -o $TMPOBJFILE
 }
@@ -236,21 +256,36 @@ usage()
     set_defaults
     DEFAULT_COPTFLAGS="$(default_coptflags $DEBUGBUILD)"
     # We assume we have a modern gcc.
-    DEFAULT_CWARNFLAGS="$(default_cwarnflags ""$DEFAULT_COPTFLAGS"" 1 1 ""$DEBUGBUILD"")"
+    DEFAULT_CWARNFLAGS="$(default_cwarnflags "$DEFAULT_COPTFLAGS" 1 1 "$DEBUGBUILD")"
     usage_with_default "CC" "$CC"
     usage_with_default "CWARNFLAGS" "$DEFAULT_CWARNFLAGS"
     usage_with_default "COPTFLAGS" "$DEFAULT_COPTFLAGS"
     usage_with_default "CDEBUGFLAGS" "$CDEBUGFLAGS"
+    usage_with_default "CFLAGS" "$CFLAGS"
+    usage_with_default "CPPFLAGS" "$CPPFLAGS"
+    usage_with_default "LDFLAGS" "$LDFLAGS"
     if [ "$(uname -s)" = "Darwin" ]; then
         echo "    Note: On macOS, -g is used instead of -g3 for libbacktrace compatibility"
     fi
     usage_with_default "CONFIGURATOR_CC" "${CONFIGURATOR_CC:-$CC}"
     echo "    To override compile line for configurator itself"
+    usage_with_default "CC_FOR_BUILD" "$CC_FOR_BUILD"
+    echo "    To set compiler driver for build system when cross-compiling"
+    usage_with_default "CFLAGS_FOR_BUILD" "$CFLAGS_FOR_BUILD"
+    echo "    To set compiler flags for build system when cross-compiling"
+    usage_with_default "CPPFLAGS_FOR_BUILD" "$CPPFLAGS_FOR_BUILD"
+    echo "    To set preprocessor flags for build system when cross-compiling"
+    usage_with_default "LDFLAGS_FOR_BUILD" "$LDFLAGS_FOR_BUILD"
+    echo "    To set linker flags for build system when cross-compiling"
     usage_with_default "PYTEST" "$PYTEST"
     usage_with_default "VALGRIND" "$VALGRIND"
     usage_with_default "SED" "$SED"
 
     echo "Options include:"
+    usage_with_default "--host=" "$HOST"
+    echo "    Compile to execute on host machine tuple"
+    usage_with_default "--build=" "$BUILD"
+    echo "    Compile on build machine tuple"
     usage_with_default "--prefix=" "$PREFIX"
     echo "    Prefix for make install"
     usage_with_default "--enable/disable-debugbuild" "$DEBUGBUILD" "enable" "disable"
@@ -277,9 +312,9 @@ usage()
 add_var()
 {
     if [ -n "$2" ]; then
-        echo "Setting $1... $2"
+        echo "Setting $1... $2" >&2
     else
-        echo "$1 not found"
+        echo "$1 not found" >&2
     fi
     echo "$1=$2" >> $CONFIG_VAR_FILE.$$
     [ -z "$3" ] || echo "#define $1 $2" >> "$3"
@@ -314,7 +349,16 @@ for opt in "$@"; do
 	CWARNFLAGS=*) CWARNFLAGS="${opt#CWARNFLAGS=}";;
 	CDEBUGFLAGS=*) CDEBUGFLAGS="${opt#CDEBUGFLAGS=}";;
 	COPTFLAGS=*) COPTFLAGS="${opt#COPTFLAGS=}";;
+	CFLAGS=*) CFLAGS="${opt#CFLAGS=}";;
+	CPPFLAGS=*) CPPFLAGS="${opt#CPPFLAGS=}";;
+	LDFLAGS=*) LDFLAGS="${opt#LDFLAGS=}";;
+	CC_FOR_BUILD=*) CC_FOR_BUILD="${opt#*=}";;
+	CFLAGS_FOR_BUILD=*) CFLAGS_FOR_BUILD="${opt#*=}";;
+	CPPFLAGS_FOR_BUILD=*) CPPFLAGS_FOR_BUILD="${opt#*=}";;
+	LDFLAGS_FOR_BUILD=*) LDFLAGS_FOR_BUILD="${opt#*=}";;
 	PYTEST=*) PYTEST="${opt#PYTEST=}";;
+	--host=*) HOST="${opt#*=}";;
+	--build=*) BUILD="${opt#*=}";;
 	--prefix=*) PREFIX="${opt#--prefix=}";;
 	--enable-debugbuild) DEBUGBUILD=1;;
 	--disable-debugbuild) DEBUGBUILD=0;;
@@ -334,10 +378,10 @@ for opt in "$@"; do
 	--disable-fuzzing) FUZZING=0;;
 	--enable-rust) RUST=1;;
 	--disable-rust) RUST=0;;
-	--help|-h) usage;;
+	--help|-h) usage >&2;;
 	*)
 	    echo "Unknown option '$opt'" >&2
-	    usage
+	    usage >&2
 	    ;;
     esac
 done
@@ -347,7 +391,7 @@ set_defaults
 
 if [ "$ASAN" = "1" ]; then
     if [ "$VALGRIND" = "1" ]; then
-	echo "Address sanitizer (ASAN) and valgrind cannot be enabled at the same time"
+	echo "Address sanitizer (ASAN) and valgrind cannot be enabled at the same time" >&2
 	exit 1
     fi
 
@@ -371,26 +415,38 @@ EOF
 fi
 
 # We call this first, so we can make sure configurator runs with it as a sanity check!
-if have_function_sections $CC "${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS"; then
-    HAVE_FUNCTION_SECTIONS=1
-    LDFLAGS="-Wl,--gc-sections"
-    COPTFLAGS="$COPTFLAGS -ffunction-sections"
-else
-    HAVE_FUNCTION_SECTIONS=0
-    LDFLAGS=
+if have_function_sections $CC "${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $CFLAGS $CPPFLAGS"; then
+    case " $CFLAGS " in
+	*' -ffunction-sections '*) ;;
+	*) CFLAGS="-ffunction-sections $CFLAGS" ;;
+    esac
+    case "$LDFLAGS" in
+	*'--gc-sections'*) ;;
+	*) LDFLAGS="-Wl,--gc-sections $LDFLAGS";;
+    esac
+    if [ "x$CC_FOR_BUILD" = "x$CC" ]; then
+	case " $CFLAGS_FOR_BUILD " in
+	    *' -ffunction-sections '*) ;;
+	    *) CFLAGS_FOR_BUILD="-ffunction-sections $CFLAGS_FOR_BUILD";;
+	esac
+	case "$LDFLAGS_FOR_BUILD" in
+	    *'--gc-sections'*) ;;
+	    *) LDFLAGS_FOR_BUILD="-Wl,--gc-sections $LDFLAGS_FOR_BUILD";;
+	esac
+    fi
 fi
 
 # We assume warning flags don't affect congfigurator that much!
-echo -n "Compiling $CONFIGURATOR..."
-$CC ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $LDFLAGS -o $CONFIGURATOR $CONFIGURATOR.c
-echo "done"
+printf 'Compiling %s...' "${CONFIGURATOR}" >&2
+$CC_FOR_BUILD $CFLAGS_FOR_BUILD $CPPFLAGS_FOR_BUILD $LDFLAGS_FOR_BUILD -o $CONFIGURATOR $CONFIGURATOR.c
+echo "done" >&2
 
 if [ "$CLANG_COVERAGE" = "1" ]; then
 	case "$CC" in
 		(*"clang"*)
 			;;
 		(*)
-			echo "Clang coverage requires building with CC=clang."
+			echo "Clang coverage requires building with CC=clang." >&2
 			exit 1
 			;;
 	esac
@@ -401,123 +457,109 @@ if [ "$FUZZING" = "1" ]; then
 		(*"clang"*)
 			;;
 		(*)
-			echo "Fuzzing is currently only supported with clang."
+			echo "Fuzzing is currently only supported with clang." >&2
 			exit 1
 			;;
 	esac
 fi
 
 
-SQLITE3_CFLAGS=""
-SQLITE3_LDLIBS="-lsqlite3"
-if command -v "${PKG_CONFIG}" >/dev/null; then
-    SQLITE3_CFLAGS="$("${PKG_CONFIG}" --silence-errors --cflags sqlite3 || :)"
-    SQLITE3_LDLIBS="$("${PKG_CONFIG}" --silence-errors --libs sqlite3 || :)"
+# Setting SQLITE3_CFLAGS or SQLITE3_LDLIBS in the environment (even to an empty
+# string) disables automagic detection via pkg-config as well as the fallback
+# default values.
+if [ -z "${SQLITE3_CFLAGS+x}" -a -z "${SQLITE3_LDLIBS+x}" ]; then
+    SQLITE3_LDLIBS="-lsqlite3"
+    if command -v "${PKG_CONFIG}" >/dev/null; then
+	SQLITE3_CFLAGS="$("${PKG_CONFIG}" --silence-errors --cflags sqlite3 || :)"
+	SQLITE3_LDLIBS="$("${PKG_CONFIG}" --silence-errors --libs sqlite3 || :)"
+    fi
 fi
 
-SODIUM_CFLAGS=""
-SODIUM_LDLIBS="-lsodium"
-if command -v "${PKG_CONFIG}" >/dev/null; then
-    SODIUM_CFLAGS="$("${PKG_CONFIG}" --silence-errors --cflags libsodium || :)"
-    SODIUM_LDLIBS="$("${PKG_CONFIG}" --silence-errors --libs libsodium || :)"
+# Setting SODIUM_CFLAGS or SODIUM_LDLIBS in the environment (even to an empty
+# string) disables automagic detection via pkg-config as well as the fallback
+# default values.
+if [ -z "${SODIUM_CFLAGS+x}" -a -z "${SODIUM_LDLIBS+x}" ]; then
+    SODIUM_LDLIBS="-lsodium"
+    if command -v "${PKG_CONFIG}" >/dev/null; then
+	SODIUM_CFLAGS="$("${PKG_CONFIG}" --silence-errors --cflags libsodium || :)"
+	SODIUM_LDLIBS="$("${PKG_CONFIG}" --silence-errors --libs libsodium || :)"
+    fi
 fi
 
-POSTGRES_INCLUDE=""
-POSTGRES_LDLIBS=""
-if command -v "${PG_CONFIG}" >/dev/null; then
-    POSTGRES_INCLUDE="-I$("${PG_CONFIG}" --includedir)"
-    POSTGRES_LDLIBS="-L$("${PG_CONFIG}" --libdir) -lpq"
+# Setting POSTGRES_INCLUDE or POSTGRES_LDLIBS in the environment (even to an
+# empty string) disables automagic detection via pg_config as well as the
+# fallback default values.
+if [ -z "${POSTGRES_INCLUDE+x}" -a -z "${POSTGRES_LDLIBS+x}" ]; then
+    POSTGRES_LDLIBS="-lpq"
+    if command -v "${PG_CONFIG}" >/dev/null; then
+	POSTGRES_INCLUDE="-I$("${PG_CONFIG}" --includedir)"
+	POSTGRES_LDLIBS="-L$("${PG_CONFIG}" --libdir) -lpq"
+    fi
 fi
 
 # Clean up on exit.
 trap "rm -f $CONFIG_VAR_FILE.$$*" 0
 
-$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER.$$ --configurator-cc="$CONFIGURATOR_CC" --wrapper="$CONFIGURATOR_WRAPPER" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $CSANFLAGS -I$CPATH -L$LIBRARY_PATH $SQLITE3_CFLAGS $SODIUM_CFLAGS $POSTGRES_INCLUDE <<EOF
+$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER.$$ --configurator-cc="$CONFIGURATOR_CC" --wrapper="$CONFIGURATOR_WRAPPER" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $CSANFLAGS $SQLITE3_CFLAGS $SODIUM_CFLAGS $CFLAGS -I$CPATH $POSTGRES_INCLUDE $CPPFLAGS -L$LIBRARY_PATH $LDFLAGS <<EOF
 
 var=HAVE_ZLIB
 desc=zlib support
-style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE
+style=OUTSIDE_MAIN
 link=-lz
 code=
 #include <zlib.h>
-#include <stdlib.h>
 
-int main(void)
-{
-	gzFile f = gzopen("/dev/null", "wb");
-	if (f != NULL) {
-		gzclose(f);
-		return 0;
-	}
-	return 1;
-}
+gzFile (*test0)(const char *, const char *) = &gzopen;
+int (*test1)(gzFile) = &gzclose;
 /*END*/
 var=HAVE_GOOD_LIBSODIUM
 desc=libsodium with IETF chacha20 variants
-style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE
-link=$SODIUM_LDLIBS
+style=OUTSIDE_MAIN
+link=${SODIUM_LDLIBS:--lsodium_disabled}
 code=
 #include <sodium.h>
-#include <stdio.h>
-#include <string.h>
 
-int main(void)
-{
-	crypto_secretstream_xchacha20poly1305_state crypto_state;
-	unsigned char header[crypto_secretstream_xchacha20poly1305_HEADERBYTES];
-	unsigned char key[crypto_secretstream_xchacha20poly1305_KEYBYTES];
-
-	crypto_secretstream_xchacha20poly1305_keygen(key);
-	crypto_secretstream_xchacha20poly1305_init_push(&crypto_state, header,
-	                                                key);
-	printf("%p\n", crypto_aead_chacha20poly1305_ietf_encrypt);
-	printf("%d\n", crypto_aead_chacha20poly1305_ietf_NPUBBYTES);
-	return 0;
-}
+void (*func0)(unsigned char *) = &crypto_secretstream_xchacha20poly1305_keygen;
+int (*func1)(crypto_secretstream_xchacha20poly1305_state *, unsigned char *,
+	     const unsigned char *)
+	= &crypto_secretstream_xchacha20poly1305_init_push;
+int (*func2)(unsigned char *, unsigned long long *, const unsigned char *,
+	     unsigned long long, const unsigned char *, unsigned long long,
+	     const unsigned char *, const unsigned char *,
+	     const unsigned char *)
+	= &crypto_aead_chacha20poly1305_ietf_encrypt;
+enum { TEST = crypto_aead_chacha20poly1305_NPUBBYTES };
 /*END*/
 var=HAVE_SQLITE3
 desc=sqlite3
-style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE
-link=$SQLITE3_LDLIBS
+style=OUTSIDE_MAIN
+link=${SQLITE3_LDLIBS:--lsqlite3_disabled}
 code=
 #include <sqlite3.h>
-#include <stdio.h>
 
-int main(void)
-{
-	printf("%p\n", sqlite3_prepare_v2);
-	return 0;
-}
+int (*func)(sqlite3 *, const char *, int, sqlite3_stmt **, const char **)
+	= &sqlite3_prepare_v2;
 /*END*/
 var=HAVE_POSTGRES
 desc=postgres
-style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE
-link=$POSTGRES_LDLIBS
+style=OUTSIDE_MAIN
+link=${POSTGRES_LDLIBS:--lpq_disabled}
 code=
 #include <libpq-fe.h>
-#include <stdio.h>
 
-int main(void)
-{
-	printf("libpq version %d\n", PQlibVersion());
-	return 0;
-}
+int (*func)(void) = &PQlibVersion;
 /*END*/
 var=HAVE_USDT
 desc=User Statically-Defined Tracing (USDT)
-style=DEFINES_EVERYTHING|EXECUTE|MAY_NOT_COMPILE
+style=DEFINES_FUNC
 code=
 #include <sys/sdt.h>
 
-int main(void)
-{
-	DTRACE_PROBE(lightningd, test_sdt);
-	return 0;
-}
+static void func(void) { DTRACE_PROBE(lightningd, test_sdt); }
 /*END*/
 var=HAVE_GCC
 desc=compiler is GCC
-style=OUTSIDE_MAIN
+style=DEFINES_EVERYTHING
 code=
 #ifndef __GNUC__
 #error "Not GCC"
@@ -528,7 +570,7 @@ code=
 /*END*/
 var=HAVE_MODERN_GCC
 desc=GCC version is 7 or above
-style=OUTSIDE_MAIN
+style=DEFINES_EVERYTHING
 code=
 #if __GNUC__ < 7
 #error "Not modern GCC"
@@ -604,12 +646,21 @@ if [ -z ${CWARNFLAGS+x} ]; then
 		    "$DEBUGBUILD")
 fi
 
+add_var HOST "$HOST"
+add_var BUILD "$BUILD"
 add_var PREFIX "$PREFIX"
 add_var CC "$CC"
 add_var CONFIGURATOR_CC "$CONFIGURATOR_CC"
 add_var CWARNFLAGS "$CWARNFLAGS"
 add_var CDEBUGFLAGS "$CDEBUGFLAGS"
 add_var COPTFLAGS "$COPTFLAGS"
+add_var CFLAGS "$CFLAGS"
+add_var CPPFLAGS "$CPPFLAGS"
+add_var LDFLAGS "$LDFLAGS"
+add_var CC_FOR_BUILD "$CC_FOR_BUILD"
+add_var CFLAGS_FOR_BUILD "$CFLAGS_FOR_BUILD"
+add_var CPPFLAGS_FOR_BUILD "$CPPFLAGS_FOR_BUILD"
+add_var LDFLAGS_FOR_BUILD "$LDFLAGS_FOR_BUILD"
 if [ -n "${SDKROOT:-}" ]; then
     add_var SDKROOT "$SDKROOT"
 fi
@@ -637,7 +688,6 @@ add_var FUZZING "$FUZZING"
 add_var RUST "$RUST"
 add_var PYTHON "$PYTHON"
 add_var SED "$SED"
-add_var HAVE_FUNCTION_SECTIONS "$HAVE_FUNCTION_SECTIONS"
 
 # Hack to avoid sha256 name clash with libwally: will be fixed when that
 # becomes a standalone shared lib.
diff --git a/connectd/Makefile b/connectd/Makefile
index 4cec6fdde40f..653cf0f19de2 100644
--- a/connectd/Makefile
+++ b/connectd/Makefile
@@ -16,27 +16,30 @@ CONNECTD_HEADERS := connectd/connectd_wiregen.h		\
 
 CONNECTD_SRC := $(CONNECTD_HEADERS:.h=.c) connectd/connectd.c
 
-CONNECTD_OBJS := $(CONNECTD_SRC:.c=.o)
+CONNECTD_OBJS := $(CONNECTD_SRC:%.c=$(BUILDDIR)/%.o)
 $(CONNECTD_OBJS): $(CONNECTD_HEADERS)
 
 WEBSOCKETD_HEADERS := connectd/sha1.h
 WEBSOCKETD_SRC := $(WEBSOCKETD_HEADERS:.h=.c) connectd/websocketd.c
 
-WEBSOCKETD_OBJS := $(WEBSOCKETD_SRC:.c=.o)
+WEBSOCKETD_OBJS := $(WEBSOCKETD_SRC:%.c=$(BUILDDIR)/%.o)
 $(WEBSOCKETD_OBJS): $(WEBSOCKETD_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(CONNECTD_SRC) $(WEBSOCKETD_SRC)
 ALL_C_HEADERS += $(CONNECTD_HEADERS) $(WEBSOCKETD_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_connectd
-ALL_PROGRAMS += lightningd/lightning_websocketd
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightning_connectd
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightning_websocketd
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += connectd/connectd_wiregen.h
-LIGHTNINGD_CONTROL_OBJS += connectd/connectd_wiregen.o
+LIGHTNINGD_CONTROL_OBJS += $(BUILDDIR)/connectd/connectd_wiregen.o
 
-lightningd/lightning_connectd: $(CONNECTD_OBJS) $(HSMD_CLIENT_OBJS) gossipd/gossipd_wiregen.o libcommon.a
+$(BUILDDIR)/lightningd/lightning_connectd: $(CONNECTD_OBJS) $(HSMD_CLIENT_OBJS) $(addprefix $(BUILDDIR)/,gossipd/gossipd_wiregen.o libcommon.a)
 
-lightningd/lightning_websocketd: $(WEBSOCKETD_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_websocketd: $(WEBSOCKETD_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) connectd/*.o
 
 include connectd/test/Makefile
diff --git a/connectd/test/Makefile b/connectd/test/Makefile
index 3bdb1c380642..ed015f4505fb 100644
--- a/connectd/test/Makefile
+++ b/connectd/test/Makefile
@@ -1,13 +1,13 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 CONNECTD_TEST_SRC := $(wildcard connectd/test/run-*.c)
-CONNECTD_TEST_OBJS := $(CONNECTD_TEST_SRC:.c=.o)
+CONNECTD_TEST_OBJS := $(CONNECTD_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 CONNECTD_TEST_PROGRAMS := $(CONNECTD_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(CONNECTD_TEST_SRC)
 ALL_TEST_PROGRAMS += $(CONNECTD_TEST_PROGRAMS)
 
-$(CONNECTD_TEST_PROGRAMS): libcommon.a
+$(CONNECTD_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 
 # Test objects depend on ../ src and headers.
 $(CONNECTD_TEST_OBJS): $(CONNECTD_HEADERS) $(CONNECTD_SRC) $(WEBSOCKETD_HEADERS) $(WEBSOCKETD_SRC) connectd/test/Makefile
diff --git a/db/Makefile b/db/Makefile
index 43380acd6245..f3f8cb82f790 100644
--- a/db/Makefile
+++ b/db/Makefile
@@ -12,7 +12,7 @@ DB_DRIVERS :=			\
 DB_SRC := $(DB_LIB_SRC) $(DB_DRIVERS)
 DB_HEADERS := $(DB_LIB_SRC:.c=.h) db/common.h
 
-DB_OBJS := $(DB_LIB_SRC:.c=.o) $(DB_DRIVERS:.c=.o)
+DB_OBJS := $(addprefix $(BUILDDIR)/,$(DB_LIB_SRC:.c=.o) $(DB_DRIVERS:.c=.o))
 $(DB_OBJS): $(DB_HEADERS)
 
 # Make sure these depend on everything.
diff --git a/devtools/Makefile b/devtools/Makefile
index 5488f162fba1..c6f35ec042df 100644
--- a/devtools/Makefile
+++ b/devtools/Makefile
@@ -1,10 +1,10 @@
-DEVTOOLS := devtools/bolt11-cli devtools/decodemsg devtools/onion devtools/dump-gossipstore devtools/gossipwith devtools/create-gossipstore devtools/mkcommit devtools/mkfunding devtools/mkclose devtools/mkgossip devtools/mkencoded devtools/mkquery devtools/lightning-checkmessage devtools/topology devtools/route devtools/bolt12-cli devtools/encodeaddr devtools/features devtools/fp16 devtools/rune devtools/gossmap-compress devtools/bip137-verifysignature devtools/convert-gossmap
+DEVTOOLS := $(addprefix $(BUILDDIR)/devtools/,bolt11-cli decodemsg onion dump-gossipstore gossipwith create-gossipstore mkcommit mkfunding mkclose mkgossip mkencoded mkquery lightning-checkmessage topology route bolt12-cli encodeaddr features fp16 rune gossmap-compress bip137-verifysignature convert-gossmap)
 ifeq ($(HAVE_SQLITE3),1)
-DEVTOOLS += devtools/checkchannels
+DEVTOOLS += $(BUILDDIR)/devtools/checkchannels
 endif
 
-DEVTOOLS_TOOL_SRC := $(DEVTOOLS:=.c) devtools/print_wire.c devtools/clean_topo.c
-DEVTOOLS_TOOL_OBJS := $(DEVTOOLS_TOOL_SRC:.c=.o)
+DEVTOOLS_TOOL_SRC := $(DEVTOOLS:$(BUILDDIR)/%=%.c) devtools/print_wire.c devtools/clean_topo.c
+DEVTOOLS_TOOL_OBJS := $(DEVTOOLS_TOOL_SRC:%.c=$(BUILDDIR)/%.o)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(DEVTOOLS_TOOL_SRC)
@@ -16,15 +16,15 @@ ifeq ($(HAVE_ZLIB),1)
 devtools/gossmap-compress_LDLIBS=-lz
 endif # ZLIB
 
-$(DEVTOOLS): %: %.o libcommon.a
+$(DEVTOOLS): %: %.o $(BUILDDIR)/libcommon.a
 $(DEVTOOLS_TOOL_OBJS): wire/wire.h
 
 # Some devtools require extra objects
-devtools/decodemsg: devtools/print_wire.o
-devtools/decodemsg.o: devtools/print_wire.h
+$(BUILDDIR)/devtools/decodemsg: $(BUILDDIR)/devtools/print_wire.o
+$(BUILDDIR)/devtools/decodemsg.o: devtools/print_wire.h
 
-devtools/mkcommit: channeld/full_channel.o channeld/commit_tx.o
-devtools/mkcommit.o: channeld/full_channel.h channeld/commit_tx.h
+$(BUILDDIR)/devtools/mkcommit: $(addprefix $(BUILDDIR)/channeld/,full_channel.o commit_tx.o)
+$(BUILDDIR)/devtools/mkcommit.o: channeld/full_channel.h channeld/commit_tx.h
 
-devtools/route devtools/topology: devtools/clean_topo.o
-devtools/route.o devtools/topology.o: devtools/clean_topo.h
+$(BUILDDIR)/devtools/route $(BUILDDIR)/devtools/topology: $(BUILDDIR)/devtools/clean_topo.o
+$(BUILDDIR)/devtools/route.o $(BUILDDIR)/devtools/topology.o: devtools/clean_topo.h
diff --git a/doc/Makefile b/doc/Makefile
index 2775eb1c9c49..30f6a0757491 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -201,21 +201,22 @@ NON_PREFIXED_MARKDOWNPAGES_WITH_EXT := $(NON_PREFIXED_MANPAGES:=.md)
 OLD_MARKDOWNPAGES_WITH_EXT := $(PREFIXED_MANPAGES:=.md)
 
 
+# Don't try to build sql.json tables with plugins/sql if we don't have sqlite3
+ifneq ($(HAVE_SQLITE3),0)
+# ...or if we're doing a cross build
+ifndef CROSS_BUILD
 # - Read the json template from schemas/sql-template.json
 # - Generate the tables schema via plugins/sql
 # - Merge both and generate final schemas/sql.json
-doc/schemas/sql.json: doc/schemas/sql-template.json plugins/sql
-	@plugins/sql --print-docs | jq --arg sqldata "$$(awk '{printf "%s\n", $$0}')" '.tables += [$$sqldata]' $< > "$@.tmp" && mv "$@.tmp" "$@";
+doc/schemas/sql.json: doc/schemas/sql-template.json $(BUILDDIR)/plugins/sql
+	@$(BUILDDIR)/plugins/sql --print-docs | jq --arg sqldata "$$(awk '{printf "%s\n", $$0}')" '.tables += [$$sqldata]' $< > "$@.tmp" && mv "$@.tmp" "$@";
+endif
+endif
 
 doc-all: $(MANPAGES) doc/index.rst
 
 SCHEMAS := $(wildcard doc/schemas/*.json) $(NOTIFICATION_SCHEMAS) $(HOOK_SCHEMAS)
 
-# Don't try to build sql.json tables with plugins/sql if we don't have sqlite3
-ifeq ($(HAVE_SQLITE3),0)
-SCHEMAS := $(filter-out doc/schemas/sql.json, $(SCHEMAS))
-endif
-
 check-fmt-schemas: $(SCHEMAS:%=check-fmt-schema/%)
 fmt-schemas: $(SCHEMAS:%=fmt-schema/%)
 
diff --git a/doc/getting-started/getting-started/installation.md b/doc/getting-started/getting-started/installation.md
index fbedcaac08e6..e7b7a70d9755 100644
--- a/doc/getting-started/getting-started/installation.md
+++ b/doc/getting-started/getting-started/installation.md
@@ -589,22 +589,10 @@ export LD=$target_host-ld
 export STRIP=$target_host-strip
 ```
 
-Two makefile targets should not be cross-compiled so we specify a native CC:
-```shell
-make CC=clang clean ccan/tools/configurator/configurator
-make clean -C ccan/ccan/cdump/tools \
-  && make CC=clang -C ccan/ccan/cdump/tools
-```
-
-Install the `qemu-user` package.
-
-This will allow you to properly configure the build for the target device environment.
-
 Build with:
 ```shell
-BUILD=x86_64 MAKE_HOST=arm-linux-androideabi \
-  make PIE=1 \
-  CONFIGURATOR_CC="arm-linux-androideabi-clang -static"
+./configure --host=$target_host
+make PIE=1
 ```
 
 ## To cross-compile for Raspberry Pi
@@ -622,13 +610,7 @@ export CC=$target_host-gcc
 export CXX=$target_host-g++
 export LD=$target_host-ld
 export STRIP=$target_host-strip
-```
-
-Install the `qemu-user` package. This will allow you to properly configure the build for the target device environment.
-
-Config the arm elf interpreter prefix:
-```shell
-export QEMU_LD_PREFIX=/path/to/raspberry/arm-bcm2708/arm-rpi-4.9.3-linux-gnueabihf/arm-linux-gnueabihf/sysroot/
+export SYSROOT=/usr/$target_host
 ```
 
 Obtain and install cross-compiled versions of sqlite3 and zlib:
@@ -638,7 +620,7 @@ Download and build zlib:
 wget https://zlib.net/fossils/zlib-1.2.13.tar.gz
 tar xvf zlib-1.2.13.tar.gz
 cd zlib-1.2.13
-./configure --prefix=$QEMU_LD_PREFIX
+./configure --prefix=$SYSROOT
 make
 make install
 ```
@@ -648,14 +630,16 @@ Download and build sqlite3:
 wget https://www.sqlite.org/2018/sqlite-src-3260000.zip
 unzip sqlite-src-3260000.zip
 cd sqlite-src-3260000
-./configure --enable-static --disable-readline --disable-threadsafe --disable-load-extension --host=$target_host --prefix=$QEMU_LD_PREFIX
+./configure --enable-static --disable-readline --disable-threadsafe --disable-load-extension --disable-tcl --host=$target_host --prefix=$SYSROOT
 make
 make install
 ```
 
 Then, build Core Lightning with the following commands:
 ```
-./configure
+export SQLITE3_CFLAGS=-I$SYSROOT/include
+export SQLITE3_LDLIBS=-lsqlite3
+./configure --host=$target_host
 make
 ```
 
diff --git a/external/Makefile b/external/Makefile
index 4ff220539eb5..efe6be80b07f 100644
--- a/external/Makefile
+++ b/external/Makefile
@@ -6,10 +6,7 @@ SUBMODULES =					\
 
 TOP := ../..
 ifdef BUILD
-CROSSCOMPILE_OPTS := --host="$(MAKE_HOST)" --build="$(BUILD)"
-TARGET_DIR := external/build-$(MAKE_HOST)
-else
-TARGET_DIR := external/build-$(shell ${CC} -dumpmachine)
+CROSSCOMPILE_OPTS := --host="$(HOST)" --build="$(BUILD)"
 endif
 
 LIBWALLY_HEADERS := external/libwally-core/include/wally_bip32.h		\
@@ -24,7 +21,7 @@ GHEAP_HEADERS := external/gheap/gheap.h
 LIBBACKTRACE_HEADERS := external/libbacktrace/backtrace.h
 
 EXTERNAL_HEADERS := $(LIBWALLY_HEADERS) $(LIBSECP_HEADERS) $(JSMN_HEADERS) $(GHEAP_HEADERS) $(LIBBACKTRACE_HEADERS)
-EXTERNAL_LIBS := ${TARGET_DIR}/libwallycore.a ${TARGET_DIR}/libsecp256k1.a ${TARGET_DIR}/libjsmn.a ${TARGET_DIR}/libbacktrace.a
+EXTERNAL_LIBS := $(addprefix $(BUILDDIR)/external/,libwallycore.a libsecp256k1.a libjsmn.a libbacktrace.a)
 
 EXTERNAL_INCLUDE_FLAGS :=					\
 	-I external/libwally-core/include/			\
@@ -32,7 +29,7 @@ EXTERNAL_INCLUDE_FLAGS :=					\
 	-I external/jsmn/					\
 	-I external/libbacktrace/				\
 	-I external/gheap/					\
-	-I ${TARGET_DIR}/libbacktrace-build
+	-I $(BUILDDIR)/external/libbacktrace-build
 
 LDLIBS += $(SODIUM_LDLIBS)
 
@@ -40,7 +37,7 @@ ifeq ($(HAVE_ZLIB),1)
 LDLIBS += -lz
 endif
 
-EXTERNAL_LDLIBS := -L${TARGET_DIR} $(patsubst lib%.a,-l%,$(notdir $(EXTERNAL_LIBS)))
+EXTERNAL_LDLIBS := -L$(BUILDDIR)/external $(patsubst lib%.a,-l%,$(notdir $(EXTERNAL_LIBS)))
 
 .PHONY: submodcheck
 
@@ -54,20 +51,20 @@ $(EXTERNAL_HEADERS): submodcheck
 
 # libsecp included in libwally.
 # Wildcards here are magic.  See http://stackoverflow.com/questions/2973445/gnu-makefile-rule-generating-a-few-targets-from-a-single-source-file
-$(TARGET_DIR)/libsecp256k1.% $(TARGET_DIR)/libwallycore.%: $(TARGET_DIR)/libwally-core-build/src/secp256k1/libsecp256k1.la $(TARGET_DIR)/libwally-core-build/src/libwallycore.la
-	$(MAKE) -C $(TARGET_DIR)/libwally-core-build DESTDIR=$$(pwd)/$(TARGET_DIR) install-exec
+$(BUILDDIR)/external/libsecp256k1.% $(BUILDDIR)/external/libwallycore.%: $(BUILDDIR)/external/libwally-core-build/src/secp256k1/libsecp256k1.la $(BUILDDIR)/external/libwally-core-build/src/libwallycore.la
+	$(MAKE) -C $(BUILDDIR)/external/libwally-core-build DESTDIR=$$(pwd)/$(BUILDDIR)/external install-exec
 
 # Build libwally-core.
 ifeq ($(DEBUGBUILD),1)
 WALLY_OPTS=--enable-debug
 endif
 
-.INTERMEDIATE: $(TARGET_DIR)/libwally-core-build/src/secp256k1/libsecp256k1.la $(TARGET_DIR)/libwally-core-build/src/libwallycore.la
+.INTERMEDIATE: $(addprefix $(BUILDDIR)/external/libwally-core-build/src/,secp256k1/libsecp256k1.la libwallycore.la)
 
-$(TARGET_DIR)/libwally-core-build/src/libwallycore.% $(TARGET_DIR)/libwally-core-build/src/secp256k1/libsecp256k1.%: $(LIBWALLY_HEADERS) $(LIBSECP_HEADERS)
+$(BUILDDIR)/external/libwally-core-build/src/libwallycore.% $(BUILDDIR)/external/libwally-core-build/src/secp256k1/libsecp256k1.%: $(LIBWALLY_HEADERS) $(LIBSECP_HEADERS)
 	cd external/libwally-core && ./tools/autogen.sh
-	mkdir -p ${TARGET_DIR}/libwally-core-build
-	cd ${TARGET_DIR}/libwally-core-build \
+	$(MKDIR_P) $(BUILDDIR)/external/libwally-core-build
+	cd $(BUILDDIR)/external/libwally-core-build \
 	&& PYTHON_VERSION=3 CFLAGS="-std=c99 $(FUZZFLAGS)" LDFLAGS="$(FUZZFLAGS)" ${TOP}/libwally-core/configure CC="$(CC)" \
 		--enable-static=yes \
 		$(CROSSCOMPILE_OPTS) \
@@ -82,28 +79,28 @@ $(TARGET_DIR)/libwally-core-build/src/libwallycore.% $(TARGET_DIR)/libwally-core
 external/jsmn/jsmn.c: external/jsmn/jsmn.h
 	[ -f $@ ]
 
-$(TARGET_DIR)/jsmn-build/jsmn.o: external/jsmn/jsmn.c Makefile
+$(BUILDDIR)/external/jsmn-build/jsmn.o: external/jsmn/jsmn.c Makefile
 	@mkdir -p $(@D)
 	$(COMPILE.c) -DJSMN_STRICT=1 -o $@ $<
 
-$(TARGET_DIR)/libjsmn.a: $(TARGET_DIR)/jsmn-build/jsmn.o
+$(BUILDDIR)/external/libjsmn.a: $(BUILDDIR)/external/jsmn-build/jsmn.o
 	$(AR) rc $@ $<
 
-.INTERMEDIATE: $(TARGET_DIR)/jsmn-build/jsmn.o
+.INTERMEDIATE: $(BUILDDIR)/external/jsmn-build/jsmn.o
 
 # Need separate build dir: changes inside submodule make git think it's dirty.
-$(TARGET_DIR)/libbacktrace.a: external/libbacktrace/backtrace.h
-	mkdir -p $(TARGET_DIR)/libbacktrace-build
-	cd $(TARGET_DIR)/libbacktrace-build && $(TOP)/libbacktrace/configure CC="$(CC)" --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --prefix=/ --libdir=/ && $(MAKE)
-	$(MAKE) -C $(TARGET_DIR)/libbacktrace-build DESTDIR=$$(pwd)/$(TARGET_DIR) install-exec
+$(BUILDDIR)/external/libbacktrace.a: external/libbacktrace/backtrace.h
+	mkdir -p $(BUILDDIR)/external/libbacktrace-build
+	cd $(BUILDDIR)/external/libbacktrace-build && $(TOP)/libbacktrace/configure CC="$(CC)" --enable-static=yes $(CROSSCOMPILE_OPTS) --enable-shared=no --prefix=/ --libdir=/ && $(MAKE)
+	$(MAKE) -C $(BUILDDIR)/external/libbacktrace-build DESTDIR=$$(pwd)/$(BUILDDIR)/external install-exec
 
 distclean: external-distclean
 clean: external-clean
 
 external-clean:
 	$(RM) $(EXTERNAL_LIBS)
-	$(RM) -rf $(TARGET_DIR)
+	$(RM) -r $(BUILDDIR)/external
 
 external-distclean:
-	$(RM) -rf ${TARGET_DIR}/libbacktrace-build ${TARGET_DIR}/libsodium-build ${TARGET_DIR}/libwally-core-build ${TARGET_DIR}/jsmn-build
+	$(RM) -r $(addprefix $(BUILDDIR)/external/,libbacktrace-build libsodium-build libwally-core-build jsmn-build)
 	$(RM) -r `git status --ignored --porcelain external/libwally-core | grep '^!! ' | cut -c3-`
diff --git a/gossipd/Makefile b/gossipd/Makefile
index 6ca4bbbef0ad..5189ac9b7fe8 100644
--- a/gossipd/Makefile
+++ b/gossipd/Makefile
@@ -11,29 +11,26 @@ GOSSIPD_HEADERS_WSRC := gossipd/gossipd_wiregen.h \
 GOSSIPD_HEADERS := $(GOSSIPD_HEADERS_WSRC)
 
 GOSSIPD_SRC := $(GOSSIPD_HEADERS_WSRC:.h=.c)
-GOSSIPD_OBJS := $(GOSSIPD_SRC:.c=.o)
+GOSSIPD_OBJS := $(GOSSIPD_SRC:%.c=$(BUILDDIR)/%.o)
 $(GOSSIPD_OBJS): $(GOSSIPD_HEADERS)
 
 GOSSIPD_COMPACT_SRC := gossipd/compactd.c
-GOSSIPD_COMPACT_OBJS := $(GOSSIPD_COMPACT_SRC:.c=.o)
+GOSSIPD_COMPACT_OBJS := $(GOSSIPD_COMPACT_SRC:%.c=$(BUILDDIR)/%.o)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(GOSSIPD_SRC) $(GOSSIPD_COMPACT_SRC)
 ALL_C_HEADERS += $(GOSSIPD_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_gossipd lightningd/lightning_gossip_compactd
+ALL_PROGRAMS += $(addprefix $(BUILDDIR)/lightningd/,lightning_gossipd lightning_gossip_compactd)
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += gossipd/gossipd_wiregen.h
-LIGHTNINGD_CONTROL_OBJS += gossipd/gossipd_wiregen.o
+LIGHTNINGD_CONTROL_OBJS += $(BUILDDIR)/gossipd/gossipd_wiregen.o
 
-lightningd/lightning_gossipd: $(GOSSIPD_OBJS) $(HSMD_CLIENT_OBJS) connectd/connectd_gossipd_wiregen.o libcommon.a
+$(BUILDDIR)/lightningd/lightning_gossipd: $(GOSSIPD_OBJS) $(HSMD_CLIENT_OBJS) $(addprefix $(BUILDDIR)/,connectd/connectd_gossipd_wiregen.o libcommon.a)
 
-lightningd/lightning_gossip_compactd: $(GOSSIPD_COMPACT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_gossip_compactd: $(GOSSIPD_COMPACT_OBJS) $(BUILDDIR)/libcommon.a
 
-# The CSV was removed, but the generated files may live on!
-clean: clean-old-gossip-gen
-
-clean-old-gossip-gen:
-	$(RM) gossipd_peerd_wiregen.*
+obsclean::
+	$(RM) gossipd_peerd_wiregen.* gossipd/*.o
 
 include gossipd/test/Makefile
diff --git a/gossipd/test/Makefile b/gossipd/test/Makefile
index a05e4fda29c7..0f7a23a5d1af 100644
--- a/gossipd/test/Makefile
+++ b/gossipd/test/Makefile
@@ -3,15 +3,18 @@ check-units: gossipd-tests
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 GOSSIPD_TEST_SRC := $(wildcard gossipd/test/run-*.c)
-GOSSIPD_TEST_OBJS := $(GOSSIPD_TEST_SRC:.c=.o)
+GOSSIPD_TEST_OBJS := $(GOSSIPD_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 GOSSIPD_TEST_PROGRAMS := $(GOSSIPD_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(GOSSIPD_TEST_SRC)
 ALL_TEST_PROGRAMS += $(GOSSIPD_TEST_PROGRAMS)
 
-$(GOSSIPD_TEST_PROGRAMS): libcommon.a
+$(GOSSIPD_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 
 # Test objects depend on ../ src and headers.
 $(GOSSIPD_TEST_OBJS): $(GOSSIPD_HEADERS) $(GOSSIPD_SRC) gossipd/test/Makefile
 
+obsclean::
+	$(RM) gossipd/test/*.o
+
 gossipd-tests: $(GOSSIPD_TEST_PROGRAMS:%=unittest/%)
diff --git a/hsmd/Makefile b/hsmd/Makefile
index c60f960eb1d4..2cfc17f220a4 100644
--- a/hsmd/Makefile
+++ b/hsmd/Makefile
@@ -6,21 +6,23 @@ HSMD_SRC := hsmd/hsmd.c	\
 	hsmd/libhsmd.c
 
 HSMD_HEADERS := hsmd/hsmd_wiregen.h hsmd/permissions.h
-HSMD_OBJS := $(HSMD_SRC:.c=.o)
+HSMD_OBJS := $(HSMD_SRC:%.c=$(BUILDDIR)/%.o)
 
 $(HSMD_OBJS): $(HSMD_HEADERS)
 
 # Other programs which use the hsm need this.
 HSMD_CLIENT_OBJS := \
+	$(addprefix $(BUILDDIR)/,		\
 	hsmd/hsmd_wiregen.o			\
 	hsmd/hsm_utxo.o				\
+	)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(HSMD_SRC)
 ALL_C_HEADERS += $(HSMD_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_hsmd
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightning_hsmd
 
-lightningd/lightning_hsmd: $(HSMD_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_hsmd: $(HSMD_OBJS) $(BUILDDIR)/libcommon.a
 
 check-source: check-hsm-versions
 
@@ -28,4 +30,7 @@ check-source: check-hsm-versions
 check-hsm-versions: hsmd/hsmd_wire.csv common/hsm_version.h
 	@SUM=`grep -vE '^(#| *$$)' hsmd/hsmd_wire.csv  | sha256sum | cut -c1-64`; if ! grep -q "$$SUM" common/hsm_version.h; then echo "*** hsmd_wire.csv changed to $$SUM without update to common/hsm_version.h">&2; exit 1; fi
 
+obsclean::
+	$(RM) hsmd/*.o
+
 -include hsmd/test/Makefile
diff --git a/lightningd/Makefile b/lightningd/Makefile
index f3ba8c0d86e4..aae3eef19f53 100644
--- a/lightningd/Makefile
+++ b/lightningd/Makefile
@@ -63,26 +63,26 @@ LIGHTNINGD_HDRS :=				\
 	$(WALLET_HDRS)
 
 
-LIGHTNINGD_OBJS := $(LIGHTNINGD_SRC:.c=.o) $(LIGHTNINGD_SRC_NOHDR:.c=.o)
+LIGHTNINGD_OBJS := $(addprefix $(BUILDDIR)/,$(LIGHTNINGD_SRC:.c=.o) $(LIGHTNINGD_SRC_NOHDR:.c=.o))
 $(LIGHTNINGD_OBJS): $(LIGHTNINGD_HDRS) $(LIGHTNINGD_CONTROL_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(LIGHTNINGD_SRC) $(LIGHTNINGD_SRC_NOHDR)
 ALL_C_HEADERS += $(LIGHTNINGD_HDRS)
-ALL_PROGRAMS += lightningd/lightningd
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightningd
 
 # We explicitly check header versions in lightningd.c
-lightningd/lightningd.o: header_versions_gen.h
+$(BUILDDIR)/lightningd/lightningd.o: header_versions_gen.h
 
 $(LIGHTNINGD_OBJS): $(LIGHTNINGD_HDRS)
 $(WALLET_OBJS): $(LIGHTNINGD_HDRS) $(DB_HEADERS)
 
 # Only the plugin component needs to depend on this header.
-lightningd/plugin.o: plugins/list_of_builtin_plugins_gen.h
+$(BUILDDIR)/lightningd/plugin.o: plugins/list_of_builtin_plugins_gen.h
 
-lightningd/channel_state_names_gen.h: lightningd/channel_state.h ccan/ccan/cdump/tools/cdump-enumstr
-	ccan/ccan/cdump/tools/cdump-enumstr lightningd/channel_state.h > $@
+lightningd/channel_state_names_gen.h: lightningd/channel_state.h $(CDUMP_ENUMSTR)
+	$(CDUMP_ENUMSTR) lightningd/channel_state.h > $@
 
-lightningd/lightningd: $(LIGHTNINGD_OBJS) $(WALLET_OBJS) $(LIGHTNINGD_CONTROL_OBJS) $(HSMD_CLIENT_OBJS) $(DB_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightningd: $(LIGHTNINGD_OBJS) $(WALLET_OBJS) $(LIGHTNINGD_CONTROL_OBJS) $(HSMD_CLIENT_OBJS) $(DB_OBJS) $(BUILDDIR)/libcommon.a
 
 include lightningd/test/Makefile
diff --git a/lightningd/test/Makefile b/lightningd/test/Makefile
index ade3d8cf7151..f025d96d0970 100644
--- a/lightningd/test/Makefile
+++ b/lightningd/test/Makefile
@@ -1,17 +1,20 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 LIGHTNINGD_TEST_SRC := $(wildcard lightningd/test/run-*.c)
-LIGHTNINGD_TEST_OBJS := $(LIGHTNINGD_TEST_SRC:.c=.o)
+LIGHTNINGD_TEST_OBJS := $(LIGHTNINGD_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 LIGHTNINGD_TEST_PROGRAMS := $(LIGHTNINGD_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(LIGHTNINGD_TEST_SRC)
 ALL_TEST_PROGRAMS += $(LIGHTNINGD_TEST_PROGRAMS)
 
 # run-find_my_abspath.c includes lightningd.c, which includes header_versions_gen.h
-lightningd/test/run-find_my_abspath.o: header_versions_gen.h
+$(BUILDDIR)/lightningd/test/run-find_my_abspath.o: header_versions_gen.h
 
-$(LIGHTNINGD_TEST_PROGRAMS): libcommon.a
+$(LIGHTNINGD_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 
 $(LIGHTNINGD_TEST_OBJS): $(LIGHTNINGD_HDRS) $(LIGHTNINGD_SRC) $(LIGHTNINGD_SRC_NOHDR) lightningd/test/Makefile
 
 check-units: $(LIGHTNINGD_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) lightningd/test/*.o
diff --git a/lightningd/test/run-close_tx_check.c b/lightningd/test/run-close_tx_check.c
index 9b132647bc64..2ef9ff64551a 100644
--- a/lightningd/test/run-close_tx_check.c
+++ b/lightningd/test/run-close_tx_check.c
@@ -2,7 +2,7 @@
 #include "../simple_close_control.c"
 #include <common/close_tx.h>
 #include <common/setup.h>
-#include <external/libwally-core/include/wally_script.h>
+#include <wally_script.h>
 #include <stdio.h>
 
 /* AUTOGENERATED MOCKS START */
diff --git a/onchaind/Makefile b/onchaind/Makefile
index b64cd0dc5640..d07d129fa400 100644
--- a/onchaind/Makefile
+++ b/onchaind/Makefile
@@ -10,25 +10,30 @@ ONCHAIND_SRC := onchaind/onchaind.c	\
 	onchaind/onchaind_wiregen.c	\
 	onchaind/onchaind_wire.c
 
-onchaind/onchain_types_names_gen.h: onchaind/onchain_types.h ccan/ccan/cdump/tools/cdump-enumstr
-	ccan/ccan/cdump/tools/cdump-enumstr onchaind/onchain_types.h > $@
+onchaind/onchain_types_names_gen.h: onchaind/onchain_types.h $(CDUMP_ENUMSTR)
+	$(CDUMP_ENUMSTR) onchaind/onchain_types.h > $@
 
-ONCHAIND_OBJS := $(ONCHAIND_SRC:.c=.o)
+ONCHAIND_OBJS := $(ONCHAIND_SRC:%.c=$(BUILDDIR)/%.o)
 $(ONCHAIND_OBJS): $(ONCHAIND_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(ONCHAIND_SRC)
 ALL_C_HEADERS += $(ONCHAIND_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_onchaind
+ALL_PROGRAMS += $(BUILDDIR)/lightningd/lightning_onchaind
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += \
 	onchaind/onchaind_wiregen.h \
 	onchaind/onchaind_wire.h
 LIGHTNINGD_CONTROL_OBJS += \
+	$(addprefix $(BUILDDIR)/, \
 	onchaind/onchaind_wiregen.o \
-	onchaind/onchaind_wire.o
+	onchaind/onchaind_wire.o \
+	)
 
-lightningd/lightning_onchaind: $(ONCHAIND_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_onchaind: $(ONCHAIND_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) onchaind/*.o
 
 include onchaind/test/Makefile
diff --git a/onchaind/test/Makefile b/onchaind/test/Makefile
index b776ea1fd1a7..9465dd504c8c 100644
--- a/onchaind/test/Makefile
+++ b/onchaind/test/Makefile
@@ -3,17 +3,18 @@ check-units: onchaind-tests
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 ONCHAIND_TEST_SRC := $(wildcard onchaind/test/run-*.c)
-ONCHAIND_TEST_OBJS := $(ONCHAIND_TEST_SRC:.c=.o)
+ONCHAIND_TEST_OBJS := $(ONCHAIND_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 ONCHAIND_TEST_PROGRAMS := $(ONCHAIND_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(ONCHAIND_TEST_SRC)
 ALL_TEST_PROGRAMS += $(ONCHAIND_TEST_PROGRAMS)
 
 # test/run-grind_feerate-bug uses its own htlc_timeout_tx()
-$(filter-out onchaind/test/run-grind_feerate-bug,$(ONCHAIND_TEST_PROGRAMS)): libcommon.a
+$(filter-out onchaind/test/run-grind_feerate-bug,$(ONCHAIND_TEST_PROGRAMS)): $(BUILDDIR)/libcommon.a
 
-onchaind/test/run-grind_feerate-bug:		\
+$(BUILDDIR)/onchaind/test/run-grind_feerate-bug: \
 	$(BITCOIN_OBJS)				\
+	$(addprefix $(BUILDDIR)/,		\
 	wire/towire.o				\
 	wire/fromwire.o				\
 	common/amount.o				\
@@ -22,10 +23,13 @@ onchaind/test/run-grind_feerate-bug:		\
 	common/psbt_keypath.o			\
 	common/pseudorand.o			\
 	common/setup.o				\
-	common/utils.o
+	common/utils.o				\
+	)
 
 # Test objects depend on ../ src and headers.
 $(ONCHAIND_TEST_OBJS): $(ONCHAIND_HEADERS) $(ONCHAIND_SRC) onchaind/test/Makefile
 
 onchaind-tests: $(ONCHAIND_TEST_PROGRAMS:%=unittest/%)
 
+obsclean::
+	$(RM) onchaind/test/*.o
diff --git a/openingd/Makefile b/openingd/Makefile
index b5a1c29f8870..88e7fdaa1fd6 100644
--- a/openingd/Makefile
+++ b/openingd/Makefile
@@ -14,23 +14,26 @@ OPENINGD_SRC := openingd/openingd.c		\
 DUALOPEND_SRC := openingd/dualopend.c		\
 	$(DUALOPEND_HEADERS:.h=.c)
 
-OPENINGD_OBJS := $(OPENINGD_SRC:.c=.o)
+OPENINGD_OBJS := $(OPENINGD_SRC:%.c=$(BUILDDIR)/%.o)
 $(OPENINGD_OBJS): $(OPENINGD_HEADERS)
 
-DUALOPEND_OBJS := $(DUALOPEND_SRC:.c=.o)
+DUALOPEND_OBJS := $(DUALOPEND_SRC:%.c=$(BUILDDIR)/%.o)
 $(DUALOPEND_OBJS): $(DUALOPEND_HEADERS)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(OPENINGD_SRC) $(DUALOPEND_SRC)
 ALL_C_HEADERS += $(OPENINGD_HEADERS) $(DUALOPEND_HEADERS)
-ALL_PROGRAMS += lightningd/lightning_openingd lightningd/lightning_dualopend
+ALL_PROGRAMS += $(addprefix $(BUILDDIR)/lightningd/,lightning_openingd lightning_dualopend)
 
 # Here's what lightningd depends on
 LIGHTNINGD_CONTROL_HEADERS += openingd/openingd_wiregen.h openingd/dualopend_wiregen.h
-LIGHTNINGD_CONTROL_OBJS += openingd/openingd_wiregen.o openingd/dualopend_wiregen.o
+LIGHTNINGD_CONTROL_OBJS += $(addprefix $(BUILDDIR)/openingd/,openingd_wiregen.o dualopend_wiregen.o)
 
-lightningd/lightning_openingd: $(OPENINGD_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_openingd: $(OPENINGD_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
 
-lightningd/lightning_dualopend: $(DUALOPEND_OBJS) $(HSMD_CLIENT_OBJS) libcommon.a
+$(BUILDDIR)/lightningd/lightning_dualopend: $(DUALOPEND_OBJS) $(HSMD_CLIENT_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) openingd/*.o
 
 -include openingd/test/Makefile
diff --git a/plugins/Makefile b/plugins/Makefile
index 9179e1d116fa..8fe4f7aad9b1 100644
--- a/plugins/Makefile
+++ b/plugins/Makefile
@@ -1,21 +1,21 @@
 PLUGIN_PAY_SRC := plugins/pay.c
 PLUGIN_PAY_HEADER :=
-PLUGIN_PAY_OBJS := $(PLUGIN_PAY_SRC:.c=.o)
+PLUGIN_PAY_OBJS := $(PLUGIN_PAY_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_AUTOCLEAN_SRC := plugins/autoclean.c
-PLUGIN_AUTOCLEAN_OBJS := $(PLUGIN_AUTOCLEAN_SRC:.c=.o)
+PLUGIN_AUTOCLEAN_OBJS := $(PLUGIN_AUTOCLEAN_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_chanbackup_SRC := plugins/chanbackup.c
-PLUGIN_chanbackup_OBJS := $(PLUGIN_chanbackup_SRC:.c=.o)
+PLUGIN_chanbackup_OBJS := $(PLUGIN_chanbackup_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_TOPOLOGY_SRC := plugins/topology.c
-PLUGIN_TOPOLOGY_OBJS := $(PLUGIN_TOPOLOGY_SRC:.c=.o)
+PLUGIN_TOPOLOGY_OBJS := $(PLUGIN_TOPOLOGY_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_TXPREPARE_SRC := plugins/txprepare.c
-PLUGIN_TXPREPARE_OBJS := $(PLUGIN_TXPREPARE_SRC:.c=.o)
+PLUGIN_TXPREPARE_OBJS := $(PLUGIN_TXPREPARE_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_BCLI_SRC := plugins/bcli.c
-PLUGIN_BCLI_OBJS := $(PLUGIN_BCLI_SRC:.c=.o)
+PLUGIN_BCLI_OBJS := $(PLUGIN_BCLI_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_BWATCH_SRC := plugins/bwatch/bwatch.c \
 	plugins/bwatch/bwatch_store.c \
@@ -27,17 +27,17 @@ PLUGIN_BWATCH_HEADER := plugins/bwatch/bwatch.h \
 	plugins/bwatch/bwatch_scanner.h \
 	plugins/bwatch/bwatch_interface.h \
 	plugins/bwatch/bwatch_wiregen.h
-PLUGIN_BWATCH_OBJS := $(PLUGIN_BWATCH_SRC:.c=.o)
+PLUGIN_BWATCH_OBJS := $(PLUGIN_BWATCH_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_COMMANDO_SRC := plugins/commando.c
-PLUGIN_COMMANDO_OBJS := $(PLUGIN_COMMANDO_SRC:.c=.o)
+PLUGIN_COMMANDO_OBJS := $(PLUGIN_COMMANDO_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_KEYSEND_SRC := plugins/keysend.c
-PLUGIN_KEYSEND_OBJS := $(PLUGIN_KEYSEND_SRC:.c=.o)
+PLUGIN_KEYSEND_OBJS := $(PLUGIN_KEYSEND_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_LIB_SRC := plugins/libplugin.c
 PLUGIN_LIB_HEADER := plugins/libplugin.h
-PLUGIN_LIB_OBJS := $(PLUGIN_LIB_SRC:.c=.o)
+PLUGIN_LIB_OBJS := $(PLUGIN_LIB_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_PAY_LIB_SRC := \
 	plugins/channel_hint.c \
@@ -47,19 +47,19 @@ PLUGIN_PAY_LIB_HEADER := \
 	plugins/channel_hint.h \
 	plugins/libplugin-pay.h
 
-PLUGIN_PAY_LIB_OBJS := $(PLUGIN_PAY_LIB_SRC:.c=.o)
+PLUGIN_PAY_LIB_OBJS := $(PLUGIN_PAY_LIB_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_OFFERS_SRC := plugins/offers.c plugins/offers_offer.c plugins/offers_invreq_hook.c plugins/offers_inv_hook.c plugins/establish_onion_path.c plugins/fetchinvoice.c plugins/offers_proof.c
-PLUGIN_OFFERS_OBJS := $(PLUGIN_OFFERS_SRC:.c=.o)
+PLUGIN_OFFERS_OBJS := $(PLUGIN_OFFERS_SRC:%.c=$(BUILDDIR)/%.o)
 PLUGIN_OFFERS_HEADER := $(PLUGIN_OFFERS_SRC:.c=.h)
 
 PLUGIN_SQL_SRC := plugins/sql.c
 PLUGIN_SQL_HEADER :=
-PLUGIN_SQL_OBJS := $(PLUGIN_SQL_SRC:.c=.o)
+PLUGIN_SQL_OBJS := $(PLUGIN_SQL_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_EXPOSESECRET_SRC := plugins/exposesecret.c
 PLUGIN_EXPOSESECRET_HEADER :=
-PLUGIN_EXPOSESECRET_OBJS := $(PLUGIN_EXPOSESECRET_SRC:.c=.o)
+PLUGIN_EXPOSESECRET_OBJS := $(PLUGIN_EXPOSESECRET_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_SPENDER_SRC :=				\
 	plugins/spender/fundchannel.c		\
@@ -75,20 +75,20 @@ PLUGIN_SPENDER_HEADER :=			\
 	plugins/spender/multifundchannel.h	\
 	plugins/spender/openchannel.h		\
 	plugins/spender/splice.h
-PLUGIN_SPENDER_OBJS := $(PLUGIN_SPENDER_SRC:.c=.o)
+PLUGIN_SPENDER_OBJS := $(PLUGIN_SPENDER_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_RECOVER_SRC := plugins/recover.c
-PLUGIN_RECOVER_OBJS := $(PLUGIN_RECOVER_SRC:.c=.o)
+PLUGIN_RECOVER_OBJS := $(PLUGIN_RECOVER_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_FUNDER_SRC :=				\
 	plugins/funder.c			\
 	plugins/funder_policy.c
 PLUGIN_FUNDER_HEADER :=				\
 	plugins/funder_policy.h
-PLUGIN_FUNDER_OBJS := $(PLUGIN_FUNDER_SRC:.c=.o)
+PLUGIN_FUNDER_OBJS := $(PLUGIN_FUNDER_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_RECKLESSRPC_SRC := plugins/recklessrpc.c
-PLUGIN_RECKLESSRPC_OBJS := $(PLUGIN_RECKLESSRPC_SRC:.c=.o)
+PLUGIN_RECKLESSRPC_OBJS := $(PLUGIN_RECKLESSRPC_SRC:%.c=$(BUILDDIR)/%.o)
 
 PLUGIN_ALL_SRC :=				\
 	$(PLUGIN_AUTOCLEAN_SRC)			\
@@ -119,6 +119,7 @@ PLUGIN_ALL_HEADER :=				\
 	$(PLUGIN_BWATCH_HEADER)
 
 C_PLUGINS :=					\
+	$(addprefix $(BUILDDIR)/,		\
 	plugins/autoclean			\
 	plugins/chanbackup			\
 	plugins/bcli				\
@@ -136,10 +137,11 @@ C_PLUGINS :=					\
 	plugins/cln-renepay			\
 	plugins/cln-xpay			\
 	plugins/spenderp			\
-	plugins/cln-askrene
+	plugins/cln-askrene			\
+	)
 
 ifeq ($(HAVE_SQLITE3),1)
-C_PLUGINS += plugins/sql
+C_PLUGINS += $(BUILDDIR)/plugins/sql
 PLUGIN_ALL_SRC += $(PLUGIN_SQL_SRC)
 PLUGIN_ALL_HEADER += $(PLUGIN_SQL_HEADER)
 endif
@@ -157,7 +159,7 @@ RUST_PLUGIN_NAMES := cln-grpc clnrest cln-lsps-client cln-lsps-service wss-proxy
 
 # Builtin plugins must be in this plugins dir to work when we're executed
 # *without* make install.
-RUST_PLUGINS := $(addprefix plugins/,$(RUST_PLUGIN_NAMES))
+RUST_PLUGINS := $(addprefix $(BUILDDIR)/plugins/,$(RUST_PLUGIN_NAMES))
 $(RUST_PLUGINS): plugins/%: $(RUST_TARGET_DIR)/%
 	@cp $< $@
 
@@ -177,48 +179,48 @@ ALL_C_SOURCES += $(PLUGIN_ALL_SRC)
 ALL_C_HEADERS += $(PLUGIN_ALL_HEADER)
 ALL_PROGRAMS += $(C_PLUGINS)
 
-PLUGIN_ALL_OBJS := $(PLUGIN_ALL_SRC:.c=.o)
+PLUGIN_ALL_OBJS := $(PLUGIN_ALL_SRC:%.c=$(BUILDDIR)/%.o)
 
 # Make all plugins depend on all plugin headers, for simplicity (and this file!)
 $(PLUGIN_ALL_OBJS): $(PLUGIN_ALL_HEADER) plugins/Makefile
 
-plugins/pay: $(PLUGIN_PAY_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/pay: $(PLUGIN_PAY_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/autoclean: $(PLUGIN_AUTOCLEAN_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/autoclean: $(PLUGIN_AUTOCLEAN_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/chanbackup: $(PLUGIN_chanbackup_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/chanbackup: $(PLUGIN_chanbackup_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/commando: $(PLUGIN_COMMANDO_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/commando: $(PLUGIN_COMMANDO_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 # Topology wants to decode node_announcement, and peer_wiregen which
 # pulls in some of bitcoin/.
-plugins/topology:  $(PLUGIN_TOPOLOGY_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/topology:  $(PLUGIN_TOPOLOGY_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/txprepare: $(PLUGIN_TXPREPARE_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/txprepare: $(PLUGIN_TXPREPARE_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/exposesecret: $(PLUGIN_EXPOSESECRET_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/exposesecret: $(PLUGIN_EXPOSESECRET_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/bcli: $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/bcli: $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/bwatch/bwatch.o: $(PLUGIN_BWATCH_HEADER)
-plugins/bwatch/bwatch_store.o: $(PLUGIN_BWATCH_HEADER)
-plugins/bwatch/bwatch_scanner.o: $(PLUGIN_BWATCH_HEADER)
-plugins/bwatch/bwatch_interface.o: $(PLUGIN_BWATCH_HEADER)
-plugins/bwatch/bwatch_wiregen.o: $(PLUGIN_BWATCH_HEADER)
-plugins/cln-bwatch: $(PLUGIN_BWATCH_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/bwatch/bwatch.o: $(PLUGIN_BWATCH_HEADER)
+$(BUILDDIR)/plugins/bwatch/bwatch_store.o: $(PLUGIN_BWATCH_HEADER)
+$(BUILDDIR)/plugins/bwatch/bwatch_scanner.o: $(PLUGIN_BWATCH_HEADER)
+$(BUILDDIR)/plugins/bwatch/bwatch_interface.o: $(PLUGIN_BWATCH_HEADER)
+$(BUILDDIR)/plugins/bwatch/bwatch_wiregen.o: $(PLUGIN_BWATCH_HEADER)
+$(BUILDDIR)/plugins/cln-bwatch: $(PLUGIN_BWATCH_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/keysend: $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) libcommon.a
-$(PLUGIN_KEYSEND_OBJS): $(PLUGIN_PAY_LIB_HEADER) libcommon.a
+$(BUILDDIR)/plugins/keysend: $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(BUILDDIR)/libcommon.a
+$(PLUGIN_KEYSEND_OBJS): $(PLUGIN_PAY_LIB_HEADER) $(BUILDDIR)/libcommon.a
 
-plugins/spenderp: $(PLUGIN_SPENDER_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/spenderp: $(PLUGIN_SPENDER_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/offers: $(PLUGIN_OFFERS_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/offers: $(PLUGIN_OFFERS_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/funder: $(PLUGIN_FUNDER_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/funder: $(PLUGIN_FUNDER_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/recover:  $(PLUGIN_RECOVER_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/recover:  $(PLUGIN_RECOVER_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
-plugins/recklessrpc: $(PLUGIN_RECKLESSRPC_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/recklessrpc: $(PLUGIN_RECKLESSRPC_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 # This covers all the low-level list RPCs which return simple arrays
 SQL_LISTRPCS := listchannels listforwards listhtlcs listinvoices listnodes listoffers listpeers listpeerchannels listclosedchannels listtransactions listsendpays listchainmoves listchannelmoves bkpr-listaccountevents bkpr-listincome listnetworkevents
@@ -248,12 +250,12 @@ plugins/sql-schema_gen.h: $(SQL_SCHEMA_PARTS)
 		echo "}\"") | tr -d " \n" > $@ \
 	)
 
-plugins/sql.o: plugins/sql-schema_gen.h
-plugins/sql: $(PLUGIN_SQL_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/sql.o: plugins/sql-schema_gen.h
+$(BUILDDIR)/plugins/sql: $(PLUGIN_SQL_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 # Generated from PLUGINS definition in plugins/Makefile
 ALL_C_HEADERS += plugins/list_of_builtin_plugins_gen.h
-PLUGIN_BASES := $(PLUGINS:plugins/%=%) $(PY_PLUGINS:plugins/%=%)
+PLUGIN_BASES := $(PLUGINS:$(BUILDDIR)/plugins/%=%) $(PY_PLUGINS:plugins/%=%)
 
 plugins/list_of_builtin_plugins_gen.h: plugins/Makefile Makefile config.vars
 	@$(call VERBOSE,GEN $@,echo "static const char *list_of_builtin_plugins[] = { $(PLUGIN_BASES:%=\"%\",) NULL };" > $@)
@@ -297,12 +299,16 @@ $(RUST_TARGET_DIR)/cln-currencyrate: ${CLN_CURRENCYRATE_PLUGIN_SRC} ${CLN_RPC_SO
 ifneq ($(RUST),0)
 include plugins/rest-plugin/Makefile
 include plugins/wss-proxy-plugin/Makefile
-DEFAULT_TARGETS += $(CLN_PLUGIN_EXAMPLES) plugins/cln-grpc plugins/clnrest plugins/cln-lsps-client plugins/cln-lsps-service plugins/wss-proxy plugins/cln-bip353 plugins/cln-currencyrate
+DEFAULT_TARGETS += $(CLN_PLUGIN_EXAMPLES) $(addprefix $(BUILDDIR)/plugins/,cln-grpc clnrest cln-lsps-client cln-lsps-service wss-proxy cln-bip353 cln-currencyrate)
 endif
 
 clean: plugins-clean
+
+obsclean::
+	$(RM) $(PLUGINS:$(BUILDDIR)/%=%) plugins/*.o
+
 plugins-clean:
-	$(RM) $(PLUGINS) $(CLN_PLUGIN_EXAMPLES)
+	$(RM) $(CLN_PLUGIN_EXAMPLES)
 	$(RM) plugins/sql-schema_gen.h
 
 include plugins/test/Makefile
diff --git a/plugins/askrene/Makefile b/plugins/askrene/Makefile
index 292059112a67..2bae722cc954 100644
--- a/plugins/askrene/Makefile
+++ b/plugins/askrene/Makefile
@@ -20,13 +20,16 @@ PLUGIN_ASKRENE_CHILD_SRC := \
 PLUGIN_ASKRENE_SRC := $(PLUGIN_ASKRENE_PARENT_SRC) $(PLUGIN_ASKRENE_CHILD_SRC)
 PLUGIN_ASKRENE_HEADER := $(PLUGIN_ASKRENE_SRC:.c=.h) plugins/askrene/child/additional_costs.h
 
-PLUGIN_ASKRENE_OBJS := $(PLUGIN_ASKRENE_SRC:.c=.o)
+PLUGIN_ASKRENE_OBJS := $(PLUGIN_ASKRENE_SRC:%.c=$(BUILDDIR)/%.o)
 
 $(PLUGIN_ASKRENE_OBJS): $(PLUGIN_ASKRENE_HEADER) plugins/askrene/Makefile
 
 PLUGIN_ALL_SRC += $(PLUGIN_ASKRENE_SRC)
 PLUGIN_ALL_HEADER += $(PLUGIN_ASKRENE_HEADER)
 
-plugins/cln-askrene: $(PLUGIN_ASKRENE_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/cln-askrene: $(PLUGIN_ASKRENE_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) plugins/askrene/*.o plugins/askrene/child/*.o
 
 include plugins/askrene/test/Makefile
diff --git a/plugins/askrene/test/Makefile b/plugins/askrene/test/Makefile
index c9e06cdab2e5..0f9030d622a5 100644
--- a/plugins/askrene/test/Makefile
+++ b/plugins/askrene/test/Makefile
@@ -1,19 +1,24 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 PLUGIN_ASKRENE_TEST_SRC := $(wildcard plugins/askrene/test/run-*.c)
-PLUGIN_ASKRENE_TEST_OBJS := $(PLUGIN_ASKRENE_TEST_SRC:.c=.o)
+PLUGIN_ASKRENE_TEST_OBJS := $(PLUGIN_ASKRENE_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 PLUGIN_ASKRENE_TEST_PROGRAMS := $(PLUGIN_ASKRENE_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(PLUGIN_ASKRENE_TEST_SRC)
 ALL_TEST_PROGRAMS += $(PLUGIN_ASKRENE_TEST_PROGRAMS)
 $(PLUGIN_RENEPAY_TEST_OBJS): $(PLUGIN_ASKRENE_SRC) plugins/askrene/test/Makefile
 
-plugins/askrene/test/run-bfs plugins/askrene/test/run-dijkstra plugins/askrene/test/run-flow plugins/askrene/test/run-mcf plugins/askrene/test/run-mcf-large: \
+$(addprefix $(BUILDDIR)/plugins/askrene/test/,run-bfs run-dijkstra run-flow run-mcf run-mcf-large): \
+	$(addprefix $(BUILDDIR)/, \
 	plugins/askrene/child/priorityqueue.o \
-	plugins/askrene/child/graph.o
+	plugins/askrene/child/graph.o \
+	)
 
-$(PLUGIN_ASKRENE_TEST_PROGRAMS): $(PLUGIN_LIB_OBJS) libcommon.a
+$(PLUGIN_ASKRENE_TEST_PROGRAMS): $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 check-askrene: $(PLUGIN_ASKRENE_TEST_PROGRAMS:%=unittest/%)
 
 check-units: check-askrene
+
+obsclean::
+	$(RM) askrene/test/*.o
diff --git a/plugins/bkpr/Makefile b/plugins/bkpr/Makefile
index b49b24924cf0..099f454bcb32 100644
--- a/plugins/bkpr/Makefile
+++ b/plugins/bkpr/Makefile
@@ -32,16 +32,16 @@ BOOKKEEPER_HEADER := 				\
 	plugins/bkpr/recorder.h			\
 	plugins/bkpr/sql.h
 
-BOOKKEEPER_OBJS := $(BOOKKEEPER_SRC:.c=.o)
+BOOKKEEPER_OBJS := $(BOOKKEEPER_SRC:%.c=$(BUILDDIR)/%.o)
 
 $(BOOKKEEPER_OBJS): $(PLUGIN_LIB_HEADER) $(BOOKKEEPER_HEADER)
 
 PLUGIN_ALL_SRC += $(BOOKKEEPER_SRC)
 PLUGIN_ALL_HEADER += $(BOOKKEEPER_HEADER)
-C_PLUGINS += plugins/bookkeeper
-PLUGINS += plugins/bookkeeper
+C_PLUGINS += $(BUILDDIR)/plugins/bookkeeper
+PLUGINS += $(BUILDDIR)/plugins/bookkeeper
 
-plugins/bookkeeper: $(BOOKKEEPER_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/bookkeeper: $(BOOKKEEPER_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 maintainer-clean: clean
 clean: bkpr-maintainer-clean
@@ -50,4 +50,7 @@ bkpr-maintainer-clean:
 	$(RM) plugins/bkpr/statements_gettextgen.po
 	$(RM) $(BOOKKEEPER_DB_QUERIES)
 
+obsclean::
+	$(RM) plugins/bkpr/*.o
+
 include plugins/bkpr/test/Makefile
diff --git a/plugins/bkpr/test/Makefile b/plugins/bkpr/test/Makefile
index c28bc00b7fbe..1c7c7cae3cdf 100644
--- a/plugins/bkpr/test/Makefile
+++ b/plugins/bkpr/test/Makefile
@@ -1,11 +1,14 @@
 BOOKKEEPER_TEST_SRC := $(wildcard plugins/bkpr/test/run-*.c)
-BOOKKEEPER_TEST_OBJS := $(BOOKKEEPER_TEST_SRC:.c=.o)
+BOOKKEEPER_TEST_OBJS := $(BOOKKEEPER_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 BOOKKEEPER_TEST_PROGRAMS := $(BOOKKEEPER_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(BOOKKEEPER_TEST_SRC)
 ALL_TEST_PROGRAMS += $(BOOKKEEPER_TEST_PROGRAMS)
 
-$(BOOKKEEPER_TEST_PROGRAMS): libcommon.a
+$(BOOKKEEPER_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 $(BOOKKEEPER_TEST_OBJS): $(BOOKKEEPER_SRC) $(BOOKKEEPER_HEADER) plugins/bkpr/test/Makefile
 
 check-units: $(BOOKKEEPER_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) plugins/bkpr/test/*.o
diff --git a/plugins/renepay/Makefile b/plugins/renepay/Makefile
index a52483e89154..48ae77317e39 100644
--- a/plugins/renepay/Makefile
+++ b/plugins/renepay/Makefile
@@ -34,7 +34,7 @@ PLUGIN_RENEPAY_HDRS :=				\
 	plugins/renepay/errorcodes.h		\
 	plugins/renepay/json.h
 
-PLUGIN_RENEPAY_OBJS := $(PLUGIN_RENEPAY_SRC:.c=.o)
+PLUGIN_RENEPAY_OBJS := $(PLUGIN_RENEPAY_SRC:%.c=$(BUILDDIR)/%.o)
 
 # Make sure these depend on everything.
 PLUGIN_ALL_SRC += $(PLUGIN_RENEPAY_SRC)
@@ -43,6 +43,9 @@ PLUGIN_ALL_HEADER += $(PLUGIN_RENEPAY_HDRS)
 # Make all plugins depend on all plugin headers, for simplicity (and this file).
 $(PLUGIN_RENEPAY_OBJS): $(PLUGIN_RENEPAY_HDRS) plugins/renepay/Makefile
 
-plugins/cln-renepay: $(PLUGIN_RENEPAY_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/cln-renepay: $(PLUGIN_RENEPAY_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) plugins/renepay/*.o
 
 include plugins/renepay/test/Makefile
diff --git a/plugins/renepay/test/Makefile b/plugins/renepay/test/Makefile
index f6dcb33cda00..6d1ab173ac0a 100644
--- a/plugins/renepay/test/Makefile
+++ b/plugins/renepay/test/Makefile
@@ -1,7 +1,7 @@
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 PLUGIN_RENEPAY_TEST_SRC := $(wildcard plugins/renepay/test/run-*.c)
-PLUGIN_RENEPAY_TEST_OBJS := $(PLUGIN_RENEPAY_TEST_SRC:.c=.o)
+PLUGIN_RENEPAY_TEST_OBJS := $(PLUGIN_RENEPAY_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 PLUGIN_RENEPAY_TEST_PROGRAMS := $(PLUGIN_RENEPAY_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(PLUGIN_RENEPAY_TEST_SRC)
@@ -9,10 +9,15 @@ ALL_TEST_PROGRAMS += $(PLUGIN_RENEPAY_TEST_PROGRAMS)
 $(PLUGIN_RENEPAY_TEST_OBJS): $(PLUGIN_RENEPAY_SRC) plugins/renepay/test/common.h plugins/renepay/test/Makefile
 
 $(PLUGIN_RENEPAY_TEST_PROGRAMS):		\
+	$(addprefix $(BUILDDIR)/,		\
 	plugins/renepay/dijkstra.o		\
 	plugins/renepay/chan_extra.o		\
-	libcommon.a
+	libcommon.a				\
+	)
 
 check-renepay: $(PLUGIN_RENEPAY_TEST_PROGRAMS:%=unittest/%)
 
 check-units: check-renepay
+
+obsclean::
+	$(RM) plugins/renepay/test/*.o
diff --git a/plugins/test/Makefile b/plugins/test/Makefile
index 5ec83035b651..6f9c0326df47 100644
--- a/plugins/test/Makefile
+++ b/plugins/test/Makefile
@@ -1,24 +1,31 @@
 # Note that these actually #include everything they need, except ccan/, bitcoin/ and wire/
 # That allows for unit testing of statics, and special effects.
 PLUGIN_TEST_SRC := $(wildcard plugins/test/run-*.c)
-PLUGIN_TEST_OBJS := $(PLUGIN_TEST_SRC:.c=.o)
+PLUGIN_TEST_OBJS := $(PLUGIN_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 PLUGIN_TEST_PROGRAMS := $(PLUGIN_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(PLUGIN_TEST_SRC)
 ALL_TEST_PROGRAMS += $(PLUGIN_TEST_PROGRAMS)
 
-plugins/test/run-route-overlong:		\
-	plugins/channel_hint.o
+$(BUILDDIR)/plugins/test/run-route-overlong:	\
+	$(addprefix $(BUILDDIR)/,		\
+	plugins/channel_hint.o			\
+	)
 
-plugins/test/run-route-calc:			\
+$(BUILDDIR)/plugins/test/run-route-calc:	\
+	$(addprefix $(BUILDDIR)/,		\
 	common/fp16.o				\
 	common/gossmap.o			\
 	common/node_id.o			\
 	common/route.o				\
-	plugins/channel_hint.o
+	plugins/channel_hint.o			\
+	)
 
-$(PLUGIN_TEST_PROGRAMS): libcommon.a
+$(PLUGIN_TEST_PROGRAMS): $(BUILDDIR)/libcommon.a
 
 $(PLUGIN_TEST_OBJS): $(PLUGIN_ALL_HEADER) $(PLUGIN_ALL_SRC) plugins/test/Makefile
 
 check-units: $(PLUGIN_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) plugins/test/*.o
diff --git a/plugins/xpay/Makefile b/plugins/xpay/Makefile
index 33f22eb117b2..84365d11c4d3 100644
--- a/plugins/xpay/Makefile
+++ b/plugins/xpay/Makefile
@@ -4,7 +4,7 @@ PLUGIN_XPAY_SRC :=				\
 
 PLUGIN_XPAY_HDRS :=
 
-PLUGIN_XPAY_OBJS := $(PLUGIN_XPAY_SRC:.c=.o)
+PLUGIN_XPAY_OBJS := $(PLUGIN_XPAY_SRC:%.c=$(BUILDDIR)/%.o)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(PLUGIN_XPAY_SRC)
@@ -13,4 +13,7 @@ ALL_C_HEADERS += $(PLUGIN_XPAY_HDRS)
 # Make all plugins depend on all plugin headers, for simplicity (and this file)
 $(PLUGIN_XPAY_OBJS): $(PLUGIN_XPAY_HDRS) $(PLUGIN_LIB_HEADER) plugins/xpay/Makefile
 
-plugins/cln-xpay: $(PLUGIN_XPAY_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/plugins/cln-xpay: $(PLUGIN_XPAY_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
+
+obsclean::
+	$(RM) plugins/xpay/*.o
diff --git a/tests/fuzz/Makefile b/tests/fuzz/Makefile
index 05a2d6646484..6657997c7f47 100644
--- a/tests/fuzz/Makefile
+++ b/tests/fuzz/Makefile
@@ -1,24 +1,24 @@
 LIBFUZZ_SRC := tests/fuzz/libfuzz.c
 LIBFUZZ_HEADERS := $(LIBFUZZ_SRC:.c=.h)
-LIBFUZZ_OBJS := $(LIBFUZZ_SRC:.c=.o)
+LIBFUZZ_OBJS := $(LIBFUZZ_SRC:%.c=$(BUILDDIR)/%.o)
 
-tests/fuzz/fuzz-connectd-handshake-act*.o: tests/fuzz/connectd_handshake.h
-tests/fuzz/fuzz-ripemd160: LDLIBS += -lcrypto
-tests/fuzz/fuzz-sha256: LDLIBS += -lcrypto
-tests/fuzz/fuzz-hmac-sha256: LDLIBS += -lcrypto
-tests/fuzz/fuzz-wire-*.o: tests/fuzz/wire.h
-tests/fuzz/fuzz-bolt12-*.o: tests/fuzz/bolt12.h
+$(BUILDDIR)/tests/fuzz/fuzz-connectd-handshake-act*.o: tests/fuzz/connectd_handshake.h
+$(BUILDDIR)/tests/fuzz/fuzz-ripemd160: LDLIBS += -lcrypto
+$(BUILDDIR)/tests/fuzz/fuzz-sha256: LDLIBS += -lcrypto
+$(BUILDDIR)/tests/fuzz/fuzz-hmac-sha256: LDLIBS += -lcrypto
+$(BUILDDIR)/tests/fuzz/fuzz-wire-*.o: tests/fuzz/wire.h
+$(BUILDDIR)/tests/fuzz/fuzz-bolt12-*.o: tests/fuzz/bolt12.h
 
-tests/fuzz/fuzz-handle_onion_message: connectd/onion_message.o connectd/connectd_wiregen.o
-tests/fuzz/fuzz-full_channel: channeld/full_channel.o channeld/commit_tx.o
-tests/fuzz/fuzz-open_channel: hsmd/hsmd_wiregen.o openingd/common.o openingd/openingd_wiregen.o
+$(BUILDDIR)/tests/fuzz/fuzz-handle_onion_message: $(addprefix $(BUILDDIR)/,connectd/onion_message.o connectd/connectd_wiregen.o)
+$(BUILDDIR)/tests/fuzz/fuzz-full_channel: $(addprefix $(BUILDDIR)/,channeld/full_channel.o channeld/commit_tx.o)
+$(BUILDDIR)/tests/fuzz/fuzz-open_channel: $(addprefix $(BUILDDIR)/,hsmd/hsmd_wiregen.o openingd/common.o openingd/openingd_wiregen.o)
 
 FUZZ_TARGETS_SRC := $(wildcard tests/fuzz/fuzz-*.c)
-FUZZ_TARGETS_OBJS := $(FUZZ_TARGETS_SRC:.c=.o)
-FUZZ_TARGETS_BIN := $(FUZZ_TARGETS_SRC:.c=)
+FUZZ_TARGETS_OBJS := $(FUZZ_TARGETS_SRC:%.c=$(BUILDDIR)/%.o)
+FUZZ_TARGETS_BIN := $(FUZZ_TARGETS_OBJS:.o=)
 
 $(FUZZ_TARGETS_OBJS): $(COMMON_HEADERS) $(WIRE_HEADERS) $(COMMON_SRC) tests/fuzz/libfuzz.h
-$(FUZZ_TARGETS_BIN): $(LIBFUZZ_OBJS) libcommon.a
+$(FUZZ_TARGETS_BIN): $(LIBFUZZ_OBJS) $(BUILDDIR)/libcommon.a
 
 ALL_C_SOURCES += $(FUZZ_TARGETS_SRC) $(LIBFUZZ_SRC)
 ALL_FUZZ_TARGETS += $(FUZZ_TARGETS_BIN)
@@ -27,3 +27,6 @@ ALL_FUZZ_TARGETS += $(FUZZ_TARGETS_BIN)
 ifneq ($(FUZZING),1)
 check-units: $(FUZZ_TARGETS_BIN:%=fuzzunittest/%)
 endif
+
+obsclean::
+	$(RM) tests/fuzz/*.o
diff --git a/tests/plugins/Makefile b/tests/plugins/Makefile
index 3a0c46851f3d..c15f1cb908e0 100644
--- a/tests/plugins/Makefile
+++ b/tests/plugins/Makefile
@@ -1,26 +1,31 @@
 PLUGIN_TESTLIBPLUGIN_SRC := tests/plugins/test_libplugin.c 
-PLUGIN_TESTLIBPLUGIN_OBJS := $(PLUGIN_TESTLIBPLUGIN_SRC:.c=.o)
+PLUGIN_TESTLIBPLUGIN_OBJS := $(PLUGIN_TESTLIBPLUGIN_SRC:%.c=$(BUILDDIR)/%.o)
 
-tests/plugins/test_libplugin: $(PLUGIN_TESTLIBPLUGIN_OBJS) $(PLUGIN_LIB_OBJS) libcommon.a
+$(BUILDDIR)/tests/plugins/test_libplugin: $(PLUGIN_TESTLIBPLUGIN_OBJS) $(PLUGIN_LIB_OBJS) $(BUILDDIR)/libcommon.a
 
 $(PLUGIN_TESTLIBPLUGIN_OBJS): $(PLUGIN_LIB_HEADER) tests/plugins/Makefile
 
 PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_SRC := tests/plugins/test_selfdisable_after_getmanifest.c 
-PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_OBJS := $(PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_SRC:.c=.o)
+PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_OBJS := $(PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_SRC:%.c=$(BUILDDIR)/%.o)
 
-tests/plugins/test_selfdisable_after_getmanifest: $(PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_OBJS) libcommon.a
+$(BUILDDIR)/tests/plugins/test_selfdisable_after_getmanifest: $(PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_OBJS) $(BUILDDIR)/libcommon.a
 
 PLUGIN_CHANNELD_FAKENET_SRC := tests/plugins/channeld_fakenet.c 
-PLUGIN_CHANNELD_FAKENET_OBJS := $(PLUGIN_CHANNELD_FAKENET_SRC:.c=.o)
+PLUGIN_CHANNELD_FAKENET_OBJS := $(PLUGIN_CHANNELD_FAKENET_SRC:%.c=$(BUILDDIR)/%.o)
 
-tests/plugins/channeld_fakenet:			\
+$(BUILDDIR)/tests/plugins/channeld_fakenet:			\
 	$(PLUGIN_CHANNELD_FAKENET_OBJS)		\
+	$(addprefix $(BUILDDIR)/,		\
 	channeld/channeld_wiregen.o		\
 	channeld/commit_tx.o			\
 	channeld/full_channel.o			\
 	channeld/inflight.o			\
-	libcommon.a
+	libcommon.a				\
+	)
 
 # Make sure these depend on everything.
-ALL_TEST_PROGRAMS += tests/plugins/test_libplugin tests/plugins/test_selfdisable_after_getmanifest tests/plugins/channeld_fakenet
+ALL_TEST_PROGRAMS += $(addprefix $(BUILDDIR)/tests/plugins/,test_libplugin test_selfdisable_after_getmanifest channeld_fakenet)
 ALL_C_SOURCES += $(PLUGIN_TESTLIBPLUGIN_SRC) $(PLUGIN_TESTSELFDISABLE_AFTER_GETMANIFEST_SRC) $(PLUGIN_CHANNELD_FAKENET_SRC)
+
+obsclean::
+	$(RM) tests/plugins/*.o
diff --git a/tools/Makefile b/tools/Makefile
index 2d86221df962..d7fff6e5806a 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -1,42 +1,34 @@
 #! /usr/bin/make
-TOOLS := tools/lightning-hsmtool tools/lightning-downgrade
-TOOLS_SRC := $(TOOLS:=.c)
-TOOLS_OBJ := $(TOOLS_SRC:.c=.o)
+TOOLS_SRC := tools/lightning-hsmtool.c tools/lightning-downgrade.c
+TOOLS_OBJS := $(TOOLS_SRC:%.c=$(BUILDDIR)/%.o)
+TOOLS := $(TOOLS_OBJS:.o=)
 
 # Make sure these depend on everything.
 ALL_C_SOURCES += $(TOOLS_SRC)
 ALL_C_HEADERS +=
 ALL_PROGRAMS += $(TOOLS)
 
-# We force make to relink this every time, to detect version changes.
-# Do it atomically, otherwise parallel builds can get upset!
-tools/headerversions: $(FORCE) tools/headerversions.o libccan.a
-	@trap "rm -f $@.tmp.$$$$" EXIT; $(LINK.o) tools/headerversions.o libccan.a $(LOADLIBES) $(LDLIBS) -o $@.tmp.$$$$ && mv -f $@.tmp.$$$$ $@
+$(TOOLS): $(BUILDDIR)/libcommon.a
 
-$(TOOLS): libcommon.a
+$(BUILDDIR)/tools/lightning-hsmtool: $(BUILDDIR)/tools/lightning-hsmtool.o
+$(BUILDDIR)/tools/lightning-downgrade.o: CFLAGS:=$(CFLAGS) -DCLN_PREV_VERSION=$(CLN_PREV_VERSION)
 
-tools/headerversions.o: ccan/config.h
-tools/lightning-hsmtool: tools/lightning-hsmtool.o
-tools/lightning-downgrade.o: CFLAGS:=$(CFLAGS) -DCLN_PREV_VERSION=$(CLN_PREV_VERSION)
-
-tools/lightning-downgrade:			\
+$(BUILDDIR)/tools/lightning-downgrade:		\
+	$(addprefix $(BUILDDIR)/,		\
 	db/exec.o				\
 	db/bindings.o				\
 	db/utils.o				\
 	wallet/datastore.o			\
 	wallet/migrations.o			\
 	plugins/askrene/datastore_wire.o	\
-	$(DB_OBJS)				\
 	$(WALLET_DB_QUERIES:.c=.o)		\
-	tools/lightning-downgrade.o
+	tools/lightning-downgrade.o		\
+	)					\
+	$(DB_OBJS)
 
 update-mocks: $(tools/lightning-downgrade.c:%=update-mocks/%.c)
 
-clean: tools-clean
-
-tools-clean:
-	$(RM) $(TOOLS) $(TOOLS_OBJ)
-	$(RM) tools/headerversions
-	$(RM) tools/headerversions.o
+obsclean::
+	$(RM) tools/headerversions tools/*.o
 
 include tools/test/Makefile
diff --git a/tools/header-versions.sh b/tools/header-versions.sh
new file mode 100755
index 000000000000..1e392f1c5cff
--- /dev/null
+++ b/tools/header-versions.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+set -e -o pipefail
+
+if [ "$#" -ne 1 ] ; then
+	echo "Usage: $0 <versionheader>" >&2
+	exit 1
+fi
+
+unset file
+if [ -f "$1" ] ; then
+	exec <"$1"
+	flock 0
+	file="$(cat)"
+fi
+
+have_sqlite3() { [ "${HAVE_SQLITE3:-0}" -ne 0 ] ; }
+if have_sqlite3 ; then
+	SQLITE_VERSION_NUMBER=$({
+			${CC:-cc} ${SQLITE3_CFLAGS} -E -o - - <<-END
+				#include <sqlite3.h>
+				SQLITE_VERSION_NUMBER
+			END
+		} | tail -n1)
+fi
+
+new=$(
+	echo "/* Generated file by $0, do not edit! */"
+	have_sqlite3 && echo "/* SQLITE3 version: ${SQLITE_VERSION_NUMBER} */"
+	echo '#include <ccan/err/err.h>'
+	have_sqlite3 && echo '#include <sqlite3.h>'
+	echo
+	echo 'static inline void check_linked_library_versions(void)'
+	echo '{'
+	have_sqlite3 && printf '%s\n' \
+	'       /* Require at least the version we compiled with. */' \
+	'	if (SQLITE_VERSION_NUMBER > sqlite3_libversion_number())' \
+	'		errx(1, "SQLITE version mismatch: compiled %u, now %u",' \
+	'		     SQLITE_VERSION_NUMBER, sqlite3_libversion_number());' \
+	'       /* Ensure the major version matches. */' \
+	'	if (SQLITE_VERSION_NUMBER + 1000000 < sqlite3_libversion_number())' \
+	'		errx(1, "SQLITE major version mismatch: compiled %u, now %u",' \
+	'		     SQLITE_VERSION_NUMBER, sqlite3_libversion_number());' \
+	'	/* Earliest supported sqlite3 version */' \
+	'	if (SQLITE_VERSION_NUMBER < 3026000)' \
+	'		errx(1, "SQLITE version %u too old (minimum 3.26)",' \
+	'		     SQLITE_VERSION_NUMBER);'
+	echo '}'
+)
+
+[ "${new}" = "${file}" ] || echo "${new}" >"$1"
diff --git a/tools/headerversions.c b/tools/headerversions.c
deleted file mode 100644
index 8cee70adf8e3..000000000000
--- a/tools/headerversions.c
+++ /dev/null
@@ -1,69 +0,0 @@
-/* Updates the given file if any library versions have changed.  This
- * is important for systemwide updates, such as sqlite3. */
-#include "config.h"
-#include <ccan/err/err.h>
-#include <ccan/read_write_all/read_write_all.h>
-#include <ccan/tal/grab_file/grab_file.h>
-#include <ccan/tal/str/str.h>
-#include <errno.h>
-#include <fcntl.h>
-#if HAVE_SQLITE3
-# include <sqlite3.h>
-# define IF_SQLITE3(...) __VA_ARGS__
-#else
-# define IF_SQLITE3(...)
-#endif
-#include <unistd.h>
-
-static const char template[] =
-	"/* Generated file by tools/headerversions, do not edit! */\n"
-	IF_SQLITE3("/* SQLITE3 version: %u */\n")
-	"#include <ccan/err/err.h>\n"
-	IF_SQLITE3("#include <sqlite3.h>\n")
-	"\n"
-	"static inline void check_linked_library_versions(void)\n"
-	"{\n"
-	IF_SQLITE3(
-	"       /* Require at least the version we compiled with. */"
-	"	if (SQLITE_VERSION_NUMBER > sqlite3_libversion_number())\n"
-	"		errx(1, \"SQLITE version mismatch: compiled %%u, now %%u\",\n"
-	"		     SQLITE_VERSION_NUMBER, sqlite3_libversion_number());\n"
-	"       /* Ensure the major version matches. */"
-	"	if (SQLITE_VERSION_NUMBER + 1000000 < sqlite3_libversion_number())\n"
-	"		errx(1, \"SQLITE major version mismatch: compiled %%u, now %%u\",\n"
-	"		     SQLITE_VERSION_NUMBER, sqlite3_libversion_number());\n"
-	"	/* Earliest supported sqlite3 version */\n"
-	"	if (SQLITE_VERSION_NUMBER < 3026000)\n"
-	"		errx(1, \"SQLITE version %%u too old (minimum 3.26)\",\n"
-	"		     SQLITE_VERSION_NUMBER);\n"
-	)
-	"}\n";
-
-int main(int argc, char *argv[])
-{
-	char *file, *new;
-
-	/* We don't bother with setup_locale(); we're a build tool */
-	err_set_progname(argv[0]);
-
-	if (argc != 2)
-		errx(1, "Usage: %s <versionheader>", argv[0]);
-
-	file = grab_file_str(NULL, argv[1]);
-	if (!file && errno != ENOENT)
-		err(1, "Reading %s", argv[1]);
-
-	new = tal_fmt(NULL, template
-		      IF_SQLITE3(, sqlite3_libversion_number()));
-	if (!file || !streq(new, file)) {
-		int fd = open(argv[1], O_TRUNC|O_WRONLY|O_CREAT, 0666);
-		if (fd < 0)
-			err(1, "Writing %s", argv[1]);
-		if (!write_all(fd, new, strlen(new)))
-			err(1, "Writing to %s", argv[1]);
-		close(fd);
-	}
-	tal_free(new);
-	tal_free(file);
-	return 0;
-}
diff --git a/tools/test/Makefile b/tools/test/Makefile
index c9482c9b00e7..d44e6a30e6e5 100644
--- a/tools/test/Makefile
+++ b/tools/test/Makefile
@@ -10,10 +10,10 @@ check-units: check-tools
 
 TOOL_TEST_INCL_SRC := tools/test/enum.c
 TOOL_GEN_SRC := tools/test/test_gen.c tools/test/print_gen.c
-TOOL_GEN_OBJS := $(TOOL_GEN_SRC:.c=.o)
+TOOL_GEN_OBJS := $(TOOL_GEN_SRC:%.c=$(BUILDDIR)/%.o)
 TOOL_GEN_HEADER := tools/test/test_gen.h tools/test/print_gen.h
 TOOL_TEST_SRC := $(wildcard tools/test/run-*.c)
-TOOL_TEST_OBJS := $(TOOL_TEST_SRC:.c=.o)
+TOOL_TEST_OBJS := $(TOOL_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 TOOL_TEST_PROGRAMS := $(TOOL_TEST_OBJS:.o=)
 
 # Get dependencies correct
@@ -22,9 +22,9 @@ ALL_C_HEADERS += $(TOOL_GEN_HEADER)
 
 TOOLS_WIRE_DEPS := $(BOLT_DEPS) tools/test/test_cases $(wildcard tools/gen/*_template)
 
-tools/test/enum.o: ccan/config.h
+$(BUILDDIR)/tools/test/enum.o: ccan/config.h
 $(TOOL_TEST_OBJS) $(TOOL_GEN_OBJS): $(TOOL_GEN_HEADER) tools/test/Makefile
-$(TOOL_TEST_PROGRAMS): $(TOOL_GEN_OBJS) tools/test/enum.o libcommon.a
+$(TOOL_TEST_PROGRAMS): $(TOOL_GEN_OBJS) $(addprefix $(BUILDDIR)/,tools/test/enum.o libcommon.a)
 
 tools/test/test_gen.h: $(TOOLS_WIRE_DEPS) tools/test/Makefile
 	$(BOLT_GEN) --page header $@ test_type < tools/test/test_cases > $@
@@ -45,6 +45,8 @@ check-tools: $(TOOL_TEST_PROGRAMS:%=unittest/%)
 
 clean: tools-test-clean
 
+obsclean::
+	$(RM) tools/test/*.o
+
 tools-test-clean:
-	$(RM) $(TOOL_GEN_HEADER) $(TOOL_GEN_SRC) $(TOOL_TEST_OBJS) $(TOOL_TEST_PROGRAMS)
-	$(RM) $(TOOL_GEN_SRC:.c=.o) tools/test/enum.o
+	$(RM) $(TOOL_GEN_HEADER) $(TOOL_GEN_SRC)
diff --git a/wallet/Makefile b/wallet/Makefile
index 1dc4364843fa..237210998fea 100644
--- a/wallet/Makefile
+++ b/wallet/Makefile
@@ -21,7 +21,7 @@ WALLET_DB_QUERIES  := 			\
 WALLET_SRC := $(WALLET_LIB_SRC) $(WALLET_LIB_SRC_NOHDR) $(WALLET_DB_QUERIES)
 WALLET_HDRS := $(WALLET_LIB_SRC:.c=.h)
 
-WALLET_OBJS := $(WALLET_SRC:.c=.o)
+WALLET_OBJS := $(WALLET_SRC:%.c=$(BUILDDIR)/%.o)
 
 # This really should be a subdir of lightningd/.  We depend on their headers!
 $(WALLET_OBJS): $(LIGHTNINGD_SRC:.c=.h)
@@ -64,4 +64,7 @@ wallet-maintainer-clean:
 	$(RM) wallet/statements_gettextgen.po
 	$(RM) $(WALLET_DB_QUERIES)
 
+obsclean::
+	$(RM) wallet/*.o
+
 include wallet/test/Makefile
diff --git a/wallet/test/Makefile b/wallet/test/Makefile
index 65869c5c6082..d51b54f11cb4 100644
--- a/wallet/test/Makefile
+++ b/wallet/test/Makefile
@@ -1,11 +1,14 @@
 WALLET_TEST_SRC := $(wildcard wallet/test/run-*.c)
-WALLET_TEST_OBJS := $(WALLET_TEST_SRC:.c=.o)
+WALLET_TEST_OBJS := $(WALLET_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 WALLET_TEST_PROGRAMS := $(WALLET_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(WALLET_TEST_SRC)
 ALL_TEST_PROGRAMS += $(WALLET_TEST_PROGRAMS)
 
-$(WALLET_TEST_PROGRAMS): wallet/db_sqlite3_sqlgen.o libcommon.a
+$(WALLET_TEST_PROGRAMS): $(addprefix $(BUILDDIR)/,wallet/db_sqlite3_sqlgen.o libcommon.a)
 $(WALLET_TEST_OBJS): $(WALLET_HDRS) $(WALLET_SRC) wallet/test/Makefile
 
 check-units: $(WALLET_TEST_PROGRAMS:%=unittest/%)
+
+obsclean::
+	$(RM) wallet/test/*.o
diff --git a/wire/Makefile b/wire/Makefile
index 656b64b4f92e..21e958a72d6f 100644
--- a/wire/Makefile
+++ b/wire/Makefile
@@ -20,7 +20,7 @@ WIRE_HEADERS :=	wire/onion_defs.h		\
 		wire/wire.h			\
 		$(WIRE_SRC:.c=.h)
 
-WIRE_OBJS := $(WIRE_SRC:.c=.o) $(WIRE_SRC_NOHDR:.c=.o)
+WIRE_OBJS := $(addprefix $(BUILDDIR)/,$(WIRE_SRC:.c=.o) $(WIRE_SRC_NOHDR:.c=.o))
 $(WIRE_OBJS): $(WIRE_HEADERS)
 
 ALL_C_SOURCES += $(WIRE_SRC) $(WIRE_SRC_NOHDR)
diff --git a/wire/test/Makefile b/wire/test/Makefile
index ad3720ae3891..476f47c8efe6 100644
--- a/wire/test/Makefile
+++ b/wire/test/Makefile
@@ -3,27 +3,31 @@ check-units: wire-tests
 # Note that these actually #include everything they need, except ccan/ and bitcoin/.
 # That allows for unit testing of statics, and special effects.
 WIRE_TEST_SRC := $(wildcard wire/test/run-*.c)
-WIRE_TEST_OBJS := $(WIRE_TEST_SRC:.c=.o)
+WIRE_TEST_OBJS := $(WIRE_TEST_SRC:%.c=$(BUILDDIR)/%.o)
 WIRE_TEST_PROGRAMS := $(WIRE_TEST_OBJS:.o=)
 
 ALL_C_SOURCES += $(WIRE_TEST_SRC)
 ALL_TEST_PROGRAMS += $(WIRE_TEST_PROGRAMS)
 
 WIRE_TEST_COMMON_OBJS :=		\
+	$(addprefix $(BUILDDIR)/,	\
 	common/autodata.o		\
 	common/base32.o			\
 	common/pseudorand.o		\
 	common/setup.o			\
 	common/utils.o			\
-	common/wireaddr.o
+	common/wireaddr.o		\
+	)
 
 # run-tlvstream.c and run-peer-wire.c provide their own mocks for randbytes_ and randbytes_overridden
 # run-tlvstream.c needs to reach into bitcoin/pubkey for SUPERVERBOSE
-$(WIRE_TEST_PROGRAMS): $(WIRE_TEST_COMMON_OBJS) $(filter-out bitcoin/pubkey.o bitcoin/chainparams.o,$(BITCOIN_OBJS))
+$(WIRE_TEST_PROGRAMS): $(WIRE_TEST_COMMON_OBJS) $(filter-out $(addprefix $(BUILDDIR)/bitcoin/,pubkey.o chainparams.o),$(BITCOIN_OBJS))
 
 $(WIRE_TEST_OBJS): $(WIRE_HEADERS) $(WIRE_SRC) $(WIRE_PRINT_SRC) wire/test/Makefile
 
 wire-tests: $(WIRE_TEST_PROGRAMS:%=unittest/%)
 
-wire/test/run-peer-wire: wire/peer_wiregen.o common/bigsize.o
+$(BUILDDIR)/wire/test/run-peer-wire: $(addprefix $(BUILDDIR)/,wire/peer_wiregen.o common/bigsize.o)
 
+obsclean::
+	$(RM) wire/test/*.o