diff --git a/src/pkg/runtime/Makefile b/src/pkg/runtime/Makefile
index c390040c45..9fb3a2bbe7 100644
--- a/src/pkg/runtime/Makefile
+++ b/src/pkg/runtime/Makefile
@@ -4,17 +4,11 @@
 
 include ../../Make.inc
 
+# Go tool will do this for package runtime.
+CFLAGS+=-DGOOS_$(GOOS) -DGOARCH_$(GOARCH)
+
 TARG=runtime
 
-# Set SIZE to 32 or 64.
-SIZE_386=32
-SIZE_amd64=64
-SIZE_arm=32
-SIZE=$(SIZE_$(GOARCH))
-
-CFLAGS_windows=-D__WINDOWS__
-CFLAGS=-I$(GOOS) -I$(GOARCH) -I$(GOOS)/$(GOARCH) -FVw $(CFLAGS_$(GOARCH)) $(CFLAGS_$(GOOS))
-
 GOFILES=\
 	debug.go\
 	error.go\
@@ -49,29 +43,29 @@ OFILES_plan9=\
 	lock_sema.$O\
 
 OFILES_windows=\
-	callback.$O\
+	callback_windows_$(GOARCH).$O\
 	lock_sema.$O\
-	syscall.$O\
+	syscall_windows.$O\
 
 # 386-specific object files
 OFILES_386=\
-	vlop.$O\
-	vlrt.$O\
+	vlop_386.$O\
+	vlrt_386.$O\
 
 # arm-specific object files
 OFILES_arm=\
-	memset.$O\
-	softfloat.$O\
-	vlop.$O\
-	vlrt.$O\
+	memset_arm.$O\
+	softfloat_arm.$O\
+	vlop_arm.$O\
+	vlrt_arm.$O\
 
 OFILES=\
 	alg.$O\
-	asm.$O\
-	atomic.$O\
+	asm_$(GOARCH).$O\
+	atomic_$(GOARCH).$O\
 	cgocall.$O\
 	chan.$O\
-	closure.$O\
+	closure_$(GOARCH).$O\
 	complex.$O\
 	cpuprof.$O\
 	float.$O\
@@ -80,8 +74,8 @@ OFILES=\
 	malloc.$O\
 	mcache.$O\
 	mcentral.$O\
-	mem.$O\
-	memmove.$O\
+	mem_$(GOOS).$O\
+	memmove_$(GOARCH).$O\
 	mfinal.$O\
 	mfixalloc.$O\
 	mgc0.$O\
@@ -90,33 +84,36 @@ OFILES=\
 	msize.$O\
 	print.$O\
 	proc.$O\
-	rt0.$O\
+	rt0_$(GOOS)_$(GOARCH).$O\
 	rune.$O\
 	runtime.$O\
 	runtime1.$O\
 	sema.$O\
-	signal.$O\
+	signal_$(GOOS)_$(GOARCH).$O\
 	sigqueue.$O\
 	slice.$O\
 	string.$O\
 	symtab.$O\
-	sys.$O\
-	thread.$O\
+	sys_$(GOOS)_$(GOARCH).$O\
+	thread_$(GOOS).$O\
 	time.$O\
-	traceback.$O\
+	traceback_$(GOARCH).$O\
 	$(OFILES_$(GOARCH))\
 	$(OFILES_$(GOOS))\
 
+AUTOHFILES=\
+	arch_GOARCH.h\
+	os_GOOS.h\
+	signals_GOOS.h\
+	defs_GOOS_GOARCH.h\
+
 HFILES=\
 	cgocall.h\
 	runtime.h\
 	hashmap.h\
 	malloc.h\
 	stack.h\
-	$(GOARCH)/asm.h\
-	$(GOOS)/os.h\
-	$(GOOS)/signals.h\
-	$(GOOS)/$(GOARCH)/defs.h\
+	$(AUTOHFILES)\
 
 GOFILES+=$(GOFILES_$(GOOS))
 
@@ -135,9 +132,9 @@ $(pkgdir)/%.h: %.h
 clean: clean-local
 
 clean-local:
-	rm -f goc2c mkversion version.go */asm.h runtime.acid.* runtime_defs.go $$(ls *.goc | sed 's/goc$$/c/')
+	rm -f goc2c mkversion version.go runtime.acid.* runtime_defs.go $$(ls *.goc | sed 's/goc$$/c/') $(AUTOHFILES)
 
-$(GOARCH)/asm.h: mkasmh.sh runtime.acid.$(GOARCH)
+asm_$(GOARCH).h: mkasmh.sh runtime.acid.$(GOARCH)
 	./mkasmh.sh >$@.x
 	mv -f $@.x $@
 
@@ -160,20 +157,7 @@ version_$(GOOS).go:
 	./goc2c "`pwd`/$<" > $@.tmp
 	mv -f $@.tmp $@
 
-%.$O:	$(GOARCH)/%.c $(HFILES)
-	$(CC) $(CFLAGS) $<
-
-%.$O:	$(GOOS)/%.c $(HFILES)
-	$(CC) $(CFLAGS) $<
-
-%.$O:	$(GOOS)/$(GOARCH)/%.c $(HFILES)
-	$(CC) $(CFLAGS) $<
-
-%.$O:	$(GOARCH)/%.s $(GOARCH)/asm.h
-	$(AS) $<
-
-%.$O:	$(GOOS)/$(GOARCH)/%.s $(GOARCH)/asm.h
-	$(AS) $<
+%.$O: asm_$(GOARCH).h
 
 # for discovering offsets inside structs when debugging
 runtime.acid.$(GOARCH): runtime.h proc.c
@@ -185,6 +169,18 @@ traceback.$O:	amd64/traceback.c
 	$(CC) $(CFLAGS) $<
 endif
 
-runtime_defs.go: proc.c iface.c hashmap.c chan.c
-	CC="$(CC)" CFLAGS="$(CFLAGS)" ./mkgodefs.sh $^ > $@.x
+runtime_defs.go: proc.c iface.c hashmap.c chan.c $(HFILES)
+	CC="$(CC)" CFLAGS="$(CFLAGS)" ./mkgodefs.sh proc.c iface.c hashmap.c chan.c > $@.x
 	mv -f $@.x $@
+
+arch_GOARCH.h: arch_$(GOARCH).h
+	cp $^ $@
+
+defs_GOOS_GOARCH.h: defs_$(GOOS)_$(GOARCH).h
+	cp $^ $@
+
+os_GOOS.h: os_$(GOOS).h
+	cp $^ $@
+
+signals_GOOS.h: signals_$(GOOS).h
+	cp $^ $@
diff --git a/src/pkg/runtime/386/arch.h b/src/pkg/runtime/arch_386.h
similarity index 100%
rename from src/pkg/runtime/386/arch.h
rename to src/pkg/runtime/arch_386.h
diff --git a/src/pkg/runtime/amd64/arch.h b/src/pkg/runtime/arch_amd64.h
similarity index 100%
rename from src/pkg/runtime/amd64/arch.h
rename to src/pkg/runtime/arch_amd64.h
diff --git a/src/pkg/runtime/arm/arch.h b/src/pkg/runtime/arch_arm.h
similarity index 100%
rename from src/pkg/runtime/arm/arch.h
rename to src/pkg/runtime/arch_arm.h
diff --git a/src/pkg/runtime/386/asm.s b/src/pkg/runtime/asm_386.s
similarity index 99%
rename from src/pkg/runtime/386/asm.s
rename to src/pkg/runtime/asm_386.s
index 04d4e214c3..c39f365d59 100644
--- a/src/pkg/runtime/386/asm.s
+++ b/src/pkg/runtime/asm_386.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 TEXT _rt0_386(SB),7,$0
 	// Linux, Windows start the FPU in extended double precision.
diff --git a/src/pkg/runtime/amd64/asm.s b/src/pkg/runtime/asm_amd64.s
similarity index 99%
rename from src/pkg/runtime/amd64/asm.s
rename to src/pkg/runtime/asm_amd64.s
index 18cdefb83d..d91421e9e3 100644
--- a/src/pkg/runtime/amd64/asm.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 TEXT _rt0_amd64(SB),7,$-8
 	// copy arguments forward on an even stack
diff --git a/src/pkg/runtime/arm/asm.s b/src/pkg/runtime/asm_arm.s
similarity index 99%
rename from src/pkg/runtime/arm/asm.s
rename to src/pkg/runtime/asm_arm.s
index c03422f10c..533c0744d7 100644
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/asm_arm.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "arm/asm.h"
+#include "asm_arm.h"
 
 // using frame size $-4 means do not save LR on stack.
 TEXT _rt0_arm(SB),7,$-4
diff --git a/src/pkg/runtime/386/atomic.c b/src/pkg/runtime/atomic_386.c
similarity index 100%
rename from src/pkg/runtime/386/atomic.c
rename to src/pkg/runtime/atomic_386.c
diff --git a/src/pkg/runtime/amd64/atomic.c b/src/pkg/runtime/atomic_amd64.c
similarity index 100%
rename from src/pkg/runtime/amd64/atomic.c
rename to src/pkg/runtime/atomic_amd64.c
diff --git a/src/pkg/runtime/arm/atomic.c b/src/pkg/runtime/atomic_arm.c
similarity index 100%
rename from src/pkg/runtime/arm/atomic.c
rename to src/pkg/runtime/atomic_arm.c
diff --git a/src/pkg/runtime/windows/386/callback.c b/src/pkg/runtime/callback_windows_386.c
similarity index 97%
rename from src/pkg/runtime/windows/386/callback.c
rename to src/pkg/runtime/callback_windows_386.c
index 11b3d294d9..fcd292fbcd 100644
--- a/src/pkg/runtime/windows/386/callback.c
+++ b/src/pkg/runtime/callback_windows_386.c
@@ -4,8 +4,8 @@
 
 #include "runtime.h"
 #include "type.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 
 // Will keep all callbacks in a linked list, so they don't get garbage collected.
 typedef	struct	Callback	Callback;
diff --git a/src/pkg/runtime/windows/amd64/callback.c b/src/pkg/runtime/callback_windows_amd64.c
similarity index 97%
rename from src/pkg/runtime/windows/amd64/callback.c
rename to src/pkg/runtime/callback_windows_amd64.c
index f6fde4fb88..99d7cb9e38 100644
--- a/src/pkg/runtime/windows/amd64/callback.c
+++ b/src/pkg/runtime/callback_windows_amd64.c
@@ -4,8 +4,8 @@
 
 #include "runtime.h"
 #include "type.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 
 // Will keep all callbacks in a linked list, so they don't get garbage collected.
 typedef	struct	Callback	Callback;
diff --git a/src/pkg/runtime/cgocall.c b/src/pkg/runtime/cgocall.c
index 4fdb912fa9..b6f23302e4 100644
--- a/src/pkg/runtime/cgocall.c
+++ b/src/pkg/runtime/cgocall.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "stack.h"
 #include "cgocall.h"
 
diff --git a/src/pkg/runtime/386/closure.c b/src/pkg/runtime/closure_386.c
similarity index 100%
rename from src/pkg/runtime/386/closure.c
rename to src/pkg/runtime/closure_386.c
diff --git a/src/pkg/runtime/amd64/closure.c b/src/pkg/runtime/closure_amd64.c
similarity index 100%
rename from src/pkg/runtime/amd64/closure.c
rename to src/pkg/runtime/closure_amd64.c
diff --git a/src/pkg/runtime/arm/closure.c b/src/pkg/runtime/closure_arm.c
similarity index 100%
rename from src/pkg/runtime/arm/closure.c
rename to src/pkg/runtime/closure_arm.c
diff --git a/src/pkg/runtime/cpuprof.c b/src/pkg/runtime/cpuprof.c
index b7cf134384..05fa0cf61a 100644
--- a/src/pkg/runtime/cpuprof.c
+++ b/src/pkg/runtime/cpuprof.c
@@ -49,7 +49,7 @@
 // in the situation when normally the goroutine "owns" handoff.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 enum
diff --git a/src/pkg/runtime/linux/defs1.go b/src/pkg/runtime/defs1_linux.go
similarity index 100%
rename from src/pkg/runtime/linux/defs1.go
rename to src/pkg/runtime/defs1_linux.go
diff --git a/src/pkg/runtime/linux/defs2.go b/src/pkg/runtime/defs2_linux.go
similarity index 100%
rename from src/pkg/runtime/linux/defs2.go
rename to src/pkg/runtime/defs2_linux.go
diff --git a/src/pkg/runtime/linux/defs_arm.go b/src/pkg/runtime/defs_arm_linux.go
similarity index 100%
rename from src/pkg/runtime/linux/defs_arm.go
rename to src/pkg/runtime/defs_arm_linux.go
diff --git a/src/pkg/runtime/darwin/defs.go b/src/pkg/runtime/defs_darwin.go
similarity index 100%
rename from src/pkg/runtime/darwin/defs.go
rename to src/pkg/runtime/defs_darwin.go
diff --git a/src/pkg/runtime/darwin/386/defs.h b/src/pkg/runtime/defs_darwin_386.h
similarity index 100%
rename from src/pkg/runtime/darwin/386/defs.h
rename to src/pkg/runtime/defs_darwin_386.h
diff --git a/src/pkg/runtime/darwin/amd64/defs.h b/src/pkg/runtime/defs_darwin_amd64.h
similarity index 100%
rename from src/pkg/runtime/darwin/amd64/defs.h
rename to src/pkg/runtime/defs_darwin_amd64.h
diff --git a/src/pkg/runtime/freebsd/defs.go b/src/pkg/runtime/defs_freebsd.go
similarity index 100%
rename from src/pkg/runtime/freebsd/defs.go
rename to src/pkg/runtime/defs_freebsd.go
diff --git a/src/pkg/runtime/freebsd/386/defs.h b/src/pkg/runtime/defs_freebsd_386.h
similarity index 100%
rename from src/pkg/runtime/freebsd/386/defs.h
rename to src/pkg/runtime/defs_freebsd_386.h
diff --git a/src/pkg/runtime/freebsd/amd64/defs.h b/src/pkg/runtime/defs_freebsd_amd64.h
similarity index 100%
rename from src/pkg/runtime/freebsd/amd64/defs.h
rename to src/pkg/runtime/defs_freebsd_amd64.h
diff --git a/src/pkg/runtime/linux/defs.go b/src/pkg/runtime/defs_linux.go
similarity index 100%
rename from src/pkg/runtime/linux/defs.go
rename to src/pkg/runtime/defs_linux.go
diff --git a/src/pkg/runtime/linux/386/defs.h b/src/pkg/runtime/defs_linux_386.h
similarity index 100%
rename from src/pkg/runtime/linux/386/defs.h
rename to src/pkg/runtime/defs_linux_386.h
diff --git a/src/pkg/runtime/linux/amd64/defs.h b/src/pkg/runtime/defs_linux_amd64.h
similarity index 100%
rename from src/pkg/runtime/linux/amd64/defs.h
rename to src/pkg/runtime/defs_linux_amd64.h
diff --git a/src/pkg/runtime/linux/arm/defs.h b/src/pkg/runtime/defs_linux_arm.h
similarity index 100%
rename from src/pkg/runtime/linux/arm/defs.h
rename to src/pkg/runtime/defs_linux_arm.h
diff --git a/src/pkg/runtime/netbsd/defs.go b/src/pkg/runtime/defs_netbsd.go
similarity index 100%
rename from src/pkg/runtime/netbsd/defs.go
rename to src/pkg/runtime/defs_netbsd.go
diff --git a/src/pkg/runtime/netbsd/386/defs.h b/src/pkg/runtime/defs_netbsd_386.h
similarity index 100%
rename from src/pkg/runtime/netbsd/386/defs.h
rename to src/pkg/runtime/defs_netbsd_386.h
diff --git a/src/pkg/runtime/netbsd/amd64/defs.h b/src/pkg/runtime/defs_netbsd_amd64.h
similarity index 100%
rename from src/pkg/runtime/netbsd/amd64/defs.h
rename to src/pkg/runtime/defs_netbsd_amd64.h
diff --git a/src/pkg/runtime/openbsd/defs.go b/src/pkg/runtime/defs_openbsd.go
similarity index 100%
rename from src/pkg/runtime/openbsd/defs.go
rename to src/pkg/runtime/defs_openbsd.go
diff --git a/src/pkg/runtime/openbsd/386/defs.h b/src/pkg/runtime/defs_openbsd_386.h
similarity index 100%
rename from src/pkg/runtime/openbsd/386/defs.h
rename to src/pkg/runtime/defs_openbsd_386.h
diff --git a/src/pkg/runtime/openbsd/amd64/defs.h b/src/pkg/runtime/defs_openbsd_amd64.h
similarity index 100%
rename from src/pkg/runtime/openbsd/amd64/defs.h
rename to src/pkg/runtime/defs_openbsd_amd64.h
diff --git a/src/pkg/runtime/plan9/386/defs.h b/src/pkg/runtime/defs_plan9_386.h
similarity index 100%
rename from src/pkg/runtime/plan9/386/defs.h
rename to src/pkg/runtime/defs_plan9_386.h
diff --git a/src/pkg/runtime/windows/defs.go b/src/pkg/runtime/defs_windows.go
similarity index 100%
rename from src/pkg/runtime/windows/defs.go
rename to src/pkg/runtime/defs_windows.go
diff --git a/src/pkg/runtime/windows/386/defs.h b/src/pkg/runtime/defs_windows_386.h
similarity index 100%
rename from src/pkg/runtime/windows/386/defs.h
rename to src/pkg/runtime/defs_windows_386.h
diff --git a/src/pkg/runtime/windows/amd64/defs.h b/src/pkg/runtime/defs_windows_amd64.h
similarity index 100%
rename from src/pkg/runtime/windows/amd64/defs.h
rename to src/pkg/runtime/defs_windows_amd64.h
diff --git a/src/pkg/runtime/iface.c b/src/pkg/runtime/iface.c
index c9d020fbeb..9f709355a8 100644
--- a/src/pkg/runtime/iface.c
+++ b/src/pkg/runtime/iface.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "type.h"
 #include "malloc.h"
 
diff --git a/src/pkg/runtime/malloc.goc b/src/pkg/runtime/malloc.goc
index 2f6f809127..b71f5e4330 100644
--- a/src/pkg/runtime/malloc.goc
+++ b/src/pkg/runtime/malloc.goc
@@ -8,10 +8,10 @@
 
 package runtime
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "stack.h"
 #include "malloc.h"
-#include "defs.h"
+#include "defs_GOOS_GOARCH.h"
 #include "type.h"
 
 MHeap runtime·mheap;
diff --git a/src/pkg/runtime/mcache.c b/src/pkg/runtime/mcache.c
index b6e1c507a6..518e00c123 100644
--- a/src/pkg/runtime/mcache.c
+++ b/src/pkg/runtime/mcache.c
@@ -7,7 +7,7 @@
 // See malloc.h for an overview.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 void*
diff --git a/src/pkg/runtime/mcentral.c b/src/pkg/runtime/mcentral.c
index 8463d4eb88..ff0c2d11ad 100644
--- a/src/pkg/runtime/mcentral.c
+++ b/src/pkg/runtime/mcentral.c
@@ -15,7 +15,7 @@
 // so that it is faster to move those lists between MCaches and MCentrals.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 static bool MCentral_Grow(MCentral *c);
diff --git a/src/pkg/runtime/darwin/mem.c b/src/pkg/runtime/mem_darwin.c
similarity index 93%
rename from src/pkg/runtime/darwin/mem.c
rename to src/pkg/runtime/mem_darwin.c
index 2fbd7a0c47..3af7af99ae 100644
--- a/src/pkg/runtime/darwin/mem.c
+++ b/src/pkg/runtime/mem_darwin.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
-#include "os.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "malloc.h"
 
 void*
diff --git a/src/pkg/runtime/freebsd/mem.c b/src/pkg/runtime/mem_freebsd.c
similarity index 95%
rename from src/pkg/runtime/freebsd/mem.c
rename to src/pkg/runtime/mem_freebsd.c
index b69bbdc6ec..d1c22583dc 100644
--- a/src/pkg/runtime/freebsd/mem.c
+++ b/src/pkg/runtime/mem_freebsd.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
-#include "os.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "malloc.h"
 
 void*
diff --git a/src/pkg/runtime/linux/mem.c b/src/pkg/runtime/mem_linux.c
similarity index 97%
rename from src/pkg/runtime/linux/mem.c
rename to src/pkg/runtime/mem_linux.c
index 62e4eda2c2..fdf02c2cac 100644
--- a/src/pkg/runtime/linux/mem.c
+++ b/src/pkg/runtime/mem_linux.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
-#include "os.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "malloc.h"
 
 enum
diff --git a/src/pkg/runtime/openbsd/mem.c b/src/pkg/runtime/mem_netbsd.c
similarity index 95%
rename from src/pkg/runtime/openbsd/mem.c
rename to src/pkg/runtime/mem_netbsd.c
index dea5038771..34ff31d908 100644
--- a/src/pkg/runtime/openbsd/mem.c
+++ b/src/pkg/runtime/mem_netbsd.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
-#include "os.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "malloc.h"
 
 enum
diff --git a/src/pkg/runtime/netbsd/mem.c b/src/pkg/runtime/mem_openbsd.c
similarity index 95%
rename from src/pkg/runtime/netbsd/mem.c
rename to src/pkg/runtime/mem_openbsd.c
index dea5038771..34ff31d908 100644
--- a/src/pkg/runtime/netbsd/mem.c
+++ b/src/pkg/runtime/mem_openbsd.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
-#include "os.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "malloc.h"
 
 enum
diff --git a/src/pkg/runtime/plan9/mem.c b/src/pkg/runtime/mem_plan9.c
similarity index 96%
rename from src/pkg/runtime/plan9/mem.c
rename to src/pkg/runtime/mem_plan9.c
index af8b9f14e7..15cbc176b6 100644
--- a/src/pkg/runtime/plan9/mem.c
+++ b/src/pkg/runtime/mem_plan9.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
-#include "os.h"
+#include "os_GOOS.h"
 
 extern byte end[];
 static byte *bloc = { end };
diff --git a/src/pkg/runtime/windows/mem.c b/src/pkg/runtime/mem_windows.c
similarity index 95%
rename from src/pkg/runtime/windows/mem.c
rename to src/pkg/runtime/mem_windows.c
index f95a1a9825..7840daa22c 100644
--- a/src/pkg/runtime/windows/mem.c
+++ b/src/pkg/runtime/mem_windows.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "os.h"
-#include "defs.h"
+#include "arch_GOARCH.h"
+#include "os_GOOS.h"
+#include "defs_GOOS_GOARCH.h"
 #include "malloc.h"
 
 enum {
diff --git a/src/pkg/runtime/386/memmove.s b/src/pkg/runtime/memmove_386.s
similarity index 100%
rename from src/pkg/runtime/386/memmove.s
rename to src/pkg/runtime/memmove_386.s
diff --git a/src/pkg/runtime/amd64/memmove.s b/src/pkg/runtime/memmove_amd64.s
similarity index 100%
rename from src/pkg/runtime/amd64/memmove.s
rename to src/pkg/runtime/memmove_amd64.s
diff --git a/src/pkg/runtime/arm/memmove.s b/src/pkg/runtime/memmove_arm.s
similarity index 100%
rename from src/pkg/runtime/arm/memmove.s
rename to src/pkg/runtime/memmove_arm.s
diff --git a/src/pkg/runtime/arm/memset.s b/src/pkg/runtime/memset_arm.s
similarity index 100%
rename from src/pkg/runtime/arm/memset.s
rename to src/pkg/runtime/memset_arm.s
diff --git a/src/pkg/runtime/mfinal.c b/src/pkg/runtime/mfinal.c
index efb42e1fbd..c6f2b54219 100644
--- a/src/pkg/runtime/mfinal.c
+++ b/src/pkg/runtime/mfinal.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 enum { debug = 0 };
diff --git a/src/pkg/runtime/mfixalloc.c b/src/pkg/runtime/mfixalloc.c
index 497b5bf132..c916d588fd 100644
--- a/src/pkg/runtime/mfixalloc.c
+++ b/src/pkg/runtime/mfixalloc.c
@@ -7,7 +7,7 @@
 // See malloc.h for overview.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 // Initialize f to allocate objects of the given size,
diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 89bad668fe..b2f22866de 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -5,7 +5,7 @@
 // Garbage collector.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 #include "stack.h"
 
diff --git a/src/pkg/runtime/mheap.c b/src/pkg/runtime/mheap.c
index ed2b248de6..d75c18d828 100644
--- a/src/pkg/runtime/mheap.c
+++ b/src/pkg/runtime/mheap.c
@@ -13,7 +13,7 @@
 // and heapmap(i) == span for all s->start <= i < s->start+s->npages.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 static MSpan *MHeap_AllocLocked(MHeap*, uintptr, int32);
diff --git a/src/pkg/runtime/mprof.goc b/src/pkg/runtime/mprof.goc
index 57923b846c..b297d41389 100644
--- a/src/pkg/runtime/mprof.goc
+++ b/src/pkg/runtime/mprof.goc
@@ -7,9 +7,9 @@
 
 package runtime
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
-#include "defs.h"
+#include "defs_GOOS_GOARCH.h"
 #include "type.h"
 
 // NOTE(rsc): Everything here could use cas if contention became an issue.
diff --git a/src/pkg/runtime/msize.c b/src/pkg/runtime/msize.c
index 5e4735a744..e6cfcdb02d 100644
--- a/src/pkg/runtime/msize.c
+++ b/src/pkg/runtime/msize.c
@@ -26,7 +26,7 @@
 // TODO(rsc): Compute max waste for any given size.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 int32 runtime·class_to_size[NumSizeClasses];
diff --git a/src/pkg/runtime/darwin/os.h b/src/pkg/runtime/os_darwin.h
similarity index 100%
rename from src/pkg/runtime/darwin/os.h
rename to src/pkg/runtime/os_darwin.h
diff --git a/src/pkg/runtime/freebsd/os.h b/src/pkg/runtime/os_freebsd.h
similarity index 100%
rename from src/pkg/runtime/freebsd/os.h
rename to src/pkg/runtime/os_freebsd.h
diff --git a/src/pkg/runtime/linux/os.h b/src/pkg/runtime/os_linux.h
similarity index 100%
rename from src/pkg/runtime/linux/os.h
rename to src/pkg/runtime/os_linux.h
diff --git a/src/pkg/runtime/netbsd/os.h b/src/pkg/runtime/os_netbsd.h
similarity index 100%
rename from src/pkg/runtime/netbsd/os.h
rename to src/pkg/runtime/os_netbsd.h
diff --git a/src/pkg/runtime/openbsd/os.h b/src/pkg/runtime/os_openbsd.h
similarity index 100%
rename from src/pkg/runtime/openbsd/os.h
rename to src/pkg/runtime/os_openbsd.h
diff --git a/src/pkg/runtime/plan9/os.h b/src/pkg/runtime/os_plan9.h
similarity index 100%
rename from src/pkg/runtime/plan9/os.h
rename to src/pkg/runtime/os_plan9.h
diff --git a/src/pkg/runtime/windows/os.h b/src/pkg/runtime/os_windows.h
similarity index 100%
rename from src/pkg/runtime/windows/os.h
rename to src/pkg/runtime/os_windows.h
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index 8f4d1ffb4c..cb45a0c299 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -3,10 +3,10 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
-#include "defs.h"
+#include "arch_GOARCH.h"
+#include "defs_GOOS_GOARCH.h"
 #include "malloc.h"
-#include "os.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 bool	runtime·iscgo;
diff --git a/src/pkg/runtime/darwin/386/rt0.s b/src/pkg/runtime/rt0_darwin_386.s
similarity index 100%
rename from src/pkg/runtime/darwin/386/rt0.s
rename to src/pkg/runtime/rt0_darwin_386.s
diff --git a/src/pkg/runtime/darwin/amd64/rt0.s b/src/pkg/runtime/rt0_darwin_amd64.s
similarity index 100%
rename from src/pkg/runtime/darwin/amd64/rt0.s
rename to src/pkg/runtime/rt0_darwin_amd64.s
diff --git a/src/pkg/runtime/freebsd/386/rt0.s b/src/pkg/runtime/rt0_freebsd_386.s
similarity index 100%
rename from src/pkg/runtime/freebsd/386/rt0.s
rename to src/pkg/runtime/rt0_freebsd_386.s
diff --git a/src/pkg/runtime/freebsd/amd64/rt0.s b/src/pkg/runtime/rt0_freebsd_amd64.s
similarity index 100%
rename from src/pkg/runtime/freebsd/amd64/rt0.s
rename to src/pkg/runtime/rt0_freebsd_amd64.s
diff --git a/src/pkg/runtime/linux/386/rt0.s b/src/pkg/runtime/rt0_linux_386.s
similarity index 100%
rename from src/pkg/runtime/linux/386/rt0.s
rename to src/pkg/runtime/rt0_linux_386.s
diff --git a/src/pkg/runtime/linux/amd64/rt0.s b/src/pkg/runtime/rt0_linux_amd64.s
similarity index 100%
rename from src/pkg/runtime/linux/amd64/rt0.s
rename to src/pkg/runtime/rt0_linux_amd64.s
diff --git a/src/pkg/runtime/linux/arm/rt0.s b/src/pkg/runtime/rt0_linux_arm.s
similarity index 100%
rename from src/pkg/runtime/linux/arm/rt0.s
rename to src/pkg/runtime/rt0_linux_arm.s
diff --git a/src/pkg/runtime/netbsd/386/rt0.s b/src/pkg/runtime/rt0_netbsd_386.s
similarity index 100%
rename from src/pkg/runtime/netbsd/386/rt0.s
rename to src/pkg/runtime/rt0_netbsd_386.s
diff --git a/src/pkg/runtime/netbsd/amd64/rt0.s b/src/pkg/runtime/rt0_netbsd_amd64.s
similarity index 100%
rename from src/pkg/runtime/netbsd/amd64/rt0.s
rename to src/pkg/runtime/rt0_netbsd_amd64.s
diff --git a/src/pkg/runtime/openbsd/386/rt0.s b/src/pkg/runtime/rt0_openbsd_386.s
similarity index 100%
rename from src/pkg/runtime/openbsd/386/rt0.s
rename to src/pkg/runtime/rt0_openbsd_386.s
diff --git a/src/pkg/runtime/openbsd/amd64/rt0.s b/src/pkg/runtime/rt0_openbsd_amd64.s
similarity index 100%
rename from src/pkg/runtime/openbsd/amd64/rt0.s
rename to src/pkg/runtime/rt0_openbsd_amd64.s
diff --git a/src/pkg/runtime/plan9/386/rt0.s b/src/pkg/runtime/rt0_plan9_386.s
similarity index 100%
rename from src/pkg/runtime/plan9/386/rt0.s
rename to src/pkg/runtime/rt0_plan9_386.s
diff --git a/src/pkg/runtime/windows/386/rt0.s b/src/pkg/runtime/rt0_windows_386.s
similarity index 100%
rename from src/pkg/runtime/windows/386/rt0.s
rename to src/pkg/runtime/rt0_windows_386.s
diff --git a/src/pkg/runtime/windows/amd64/rt0.s b/src/pkg/runtime/rt0_windows_amd64.s
similarity index 93%
rename from src/pkg/runtime/windows/amd64/rt0.s
rename to src/pkg/runtime/rt0_windows_amd64.s
index 35978bc746..5dc6b6e51b 100644
--- a/src/pkg/runtime/windows/amd64/rt0.s
+++ b/src/pkg/runtime/rt0_windows_amd64.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 TEXT	_rt0_amd64_windows(SB),7,$-8
 	MOVQ	$_rt0_amd64(SB), AX
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 3bcb0cd008..7ab7a3fdd6 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -241,7 +241,7 @@ struct	M
 	uint32	waitsemacount;
 	uint32	waitsemalock;
 
-#ifdef __WINDOWS__
+#ifdef GOOS_windows
 	void*	thread;		// thread handle
 #endif
 	uintptr	end[];
@@ -299,7 +299,7 @@ struct	WinCall
 	uintptr	err;	// error number
 };
 
-#ifdef __WINDOWS__
+#ifdef GOOS_windows
 enum {
    Windows = 1
 };
diff --git a/src/pkg/runtime/sema.goc b/src/pkg/runtime/sema.goc
index 9f3f4a2b39..67c90350b6 100644
--- a/src/pkg/runtime/sema.goc
+++ b/src/pkg/runtime/sema.goc
@@ -19,7 +19,7 @@
 
 package runtime
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 
 typedef struct Sema Sema;
 struct Sema
diff --git a/src/pkg/runtime/darwin/386/signal.c b/src/pkg/runtime/signal_darwin_386.c
similarity index 98%
rename from src/pkg/runtime/darwin/386/signal.c
rename to src/pkg/runtime/signal_darwin_386.c
index 95c48b2583..c1cab2ccaa 100644
--- a/src/pkg/runtime/darwin/386/signal.c
+++ b/src/pkg/runtime/signal_darwin_386.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
-#include "signals.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "signals_GOOS.h"
 
 void
 runtime·dumpregs(Regs32 *r)
diff --git a/src/pkg/runtime/darwin/amd64/signal.c b/src/pkg/runtime/signal_darwin_amd64.c
similarity index 98%
rename from src/pkg/runtime/darwin/amd64/signal.c
rename to src/pkg/runtime/signal_darwin_amd64.c
index c0ef89fc60..fd75e78454 100644
--- a/src/pkg/runtime/darwin/amd64/signal.c
+++ b/src/pkg/runtime/signal_darwin_amd64.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
-#include "signals.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "signals_GOOS.h"
 
 void
 runtime·dumpregs(Regs64 *r)
diff --git a/src/pkg/runtime/freebsd/386/signal.c b/src/pkg/runtime/signal_freebsd_386.c
similarity index 98%
rename from src/pkg/runtime/freebsd/386/signal.c
rename to src/pkg/runtime/signal_freebsd_386.c
index 2fe7ecd707..ff4aaabdb5 100644
--- a/src/pkg/runtime/freebsd/386/signal.c
+++ b/src/pkg/runtime/signal_freebsd_386.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/freebsd/amd64/signal.c b/src/pkg/runtime/signal_freebsd_amd64.c
similarity index 98%
rename from src/pkg/runtime/freebsd/amd64/signal.c
rename to src/pkg/runtime/signal_freebsd_amd64.c
index 8015e366e6..2683f4fd09 100644
--- a/src/pkg/runtime/freebsd/amd64/signal.c
+++ b/src/pkg/runtime/signal_freebsd_amd64.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/linux/386/signal.c b/src/pkg/runtime/signal_linux_386.c
similarity index 98%
rename from src/pkg/runtime/linux/386/signal.c
rename to src/pkg/runtime/signal_linux_386.c
index 4045b2efc3..4f3abcebb3 100644
--- a/src/pkg/runtime/linux/386/signal.c
+++ b/src/pkg/runtime/signal_linux_386.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 void
 runtime·dumpregs(Sigcontext *r)
diff --git a/src/pkg/runtime/linux/amd64/signal.c b/src/pkg/runtime/signal_linux_amd64.c
similarity index 98%
rename from src/pkg/runtime/linux/amd64/signal.c
rename to src/pkg/runtime/signal_linux_amd64.c
index ee90271ed2..937d5c3478 100644
--- a/src/pkg/runtime/linux/amd64/signal.c
+++ b/src/pkg/runtime/signal_linux_amd64.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 void
 runtime·dumpregs(Sigcontext *r)
diff --git a/src/pkg/runtime/linux/arm/signal.c b/src/pkg/runtime/signal_linux_arm.c
similarity index 98%
rename from src/pkg/runtime/linux/arm/signal.c
rename to src/pkg/runtime/signal_linux_arm.c
index 88a84d1120..b32ec7a226 100644
--- a/src/pkg/runtime/linux/arm/signal.c
+++ b/src/pkg/runtime/signal_linux_arm.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 void
 runtime·dumpregs(Sigcontext *r)
diff --git a/src/pkg/runtime/openbsd/386/signal.c b/src/pkg/runtime/signal_netbsd_386.c
similarity index 98%
rename from src/pkg/runtime/openbsd/386/signal.c
rename to src/pkg/runtime/signal_netbsd_386.c
index 8b0d4ac616..74fa1d490b 100644
--- a/src/pkg/runtime/openbsd/386/signal.c
+++ b/src/pkg/runtime/signal_netbsd_386.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/netbsd/amd64/signal.c b/src/pkg/runtime/signal_netbsd_amd64.c
similarity index 98%
rename from src/pkg/runtime/netbsd/amd64/signal.c
rename to src/pkg/runtime/signal_netbsd_amd64.c
index 01bc76d207..6c69fa7339 100644
--- a/src/pkg/runtime/netbsd/amd64/signal.c
+++ b/src/pkg/runtime/signal_netbsd_amd64.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/netbsd/386/signal.c b/src/pkg/runtime/signal_openbsd_386.c
similarity index 98%
rename from src/pkg/runtime/netbsd/386/signal.c
rename to src/pkg/runtime/signal_openbsd_386.c
index 8b0d4ac616..74fa1d490b 100644
--- a/src/pkg/runtime/netbsd/386/signal.c
+++ b/src/pkg/runtime/signal_openbsd_386.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/openbsd/amd64/signal.c b/src/pkg/runtime/signal_openbsd_amd64.c
similarity index 98%
rename from src/pkg/runtime/openbsd/amd64/signal.c
rename to src/pkg/runtime/signal_openbsd_amd64.c
index 01bc76d207..6c69fa7339 100644
--- a/src/pkg/runtime/openbsd/amd64/signal.c
+++ b/src/pkg/runtime/signal_openbsd_amd64.c
@@ -3,9 +3,9 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "signals_GOOS.h"
+#include "os_GOOS.h"
 
 extern void runtime·sigtramp(void);
 
diff --git a/src/pkg/runtime/plan9/386/signal.c b/src/pkg/runtime/signal_plan9_386.c
similarity index 100%
rename from src/pkg/runtime/plan9/386/signal.c
rename to src/pkg/runtime/signal_plan9_386.c
diff --git a/src/pkg/runtime/windows/386/signal.c b/src/pkg/runtime/signal_windows_386.c
similarity index 97%
rename from src/pkg/runtime/windows/386/signal.c
rename to src/pkg/runtime/signal_windows_386.c
index 8d049c9f32..48d2a8bff9 100644
--- a/src/pkg/runtime/windows/386/signal.c
+++ b/src/pkg/runtime/signal_windows_386.c
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 
 void
 runtime·dumpregs(Context *r)
diff --git a/src/pkg/runtime/windows/amd64/signal.c b/src/pkg/runtime/signal_windows_amd64.c
similarity index 98%
rename from src/pkg/runtime/windows/amd64/signal.c
rename to src/pkg/runtime/signal_windows_amd64.c
index 97106c8b84..92cdb8054f 100644
--- a/src/pkg/runtime/windows/amd64/signal.c
+++ b/src/pkg/runtime/signal_windows_amd64.c
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 
 extern void *runtime·sigtramp;
 
diff --git a/src/pkg/runtime/darwin/signals.h b/src/pkg/runtime/signals_darwin.h
similarity index 100%
rename from src/pkg/runtime/darwin/signals.h
rename to src/pkg/runtime/signals_darwin.h
diff --git a/src/pkg/runtime/freebsd/signals.h b/src/pkg/runtime/signals_freebsd.h
similarity index 100%
rename from src/pkg/runtime/freebsd/signals.h
rename to src/pkg/runtime/signals_freebsd.h
diff --git a/src/pkg/runtime/linux/signals.h b/src/pkg/runtime/signals_linux.h
similarity index 100%
rename from src/pkg/runtime/linux/signals.h
rename to src/pkg/runtime/signals_linux.h
diff --git a/src/pkg/runtime/netbsd/signals.h b/src/pkg/runtime/signals_netbsd.h
similarity index 100%
rename from src/pkg/runtime/netbsd/signals.h
rename to src/pkg/runtime/signals_netbsd.h
diff --git a/src/pkg/runtime/openbsd/signals.h b/src/pkg/runtime/signals_openbsd.h
similarity index 100%
rename from src/pkg/runtime/openbsd/signals.h
rename to src/pkg/runtime/signals_openbsd.h
diff --git a/src/pkg/runtime/plan9/signals.h b/src/pkg/runtime/signals_plan9.h
similarity index 100%
rename from src/pkg/runtime/plan9/signals.h
rename to src/pkg/runtime/signals_plan9.h
diff --git a/src/pkg/runtime/windows/signals.h b/src/pkg/runtime/signals_windows.h
similarity index 100%
rename from src/pkg/runtime/windows/signals.h
rename to src/pkg/runtime/signals_windows.h
diff --git a/src/pkg/runtime/sigqueue.goc b/src/pkg/runtime/sigqueue.goc
index 504590a54e..3c12e5caf5 100644
--- a/src/pkg/runtime/sigqueue.goc
+++ b/src/pkg/runtime/sigqueue.goc
@@ -38,7 +38,7 @@
 
 package runtime
 #include "runtime.h"
-#include "defs.h"
+#include "defs_GOOS_GOARCH.h"
 
 static struct {
 	Note;
diff --git a/src/pkg/runtime/slice.c b/src/pkg/runtime/slice.c
index 3bc5cff080..e5726c93b9 100644
--- a/src/pkg/runtime/slice.c
+++ b/src/pkg/runtime/slice.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "type.h"
 #include "malloc.h"
 
diff --git a/src/pkg/runtime/arm/softfloat.c b/src/pkg/runtime/softfloat_arm.c
similarity index 100%
rename from src/pkg/runtime/arm/softfloat.c
rename to src/pkg/runtime/softfloat_arm.c
diff --git a/src/pkg/runtime/stack.h b/src/pkg/runtime/stack.h
index 483233876a..f56dac120f 100644
--- a/src/pkg/runtime/stack.h
+++ b/src/pkg/runtime/stack.h
@@ -57,7 +57,7 @@ enum {
 	// to each stack below the usual guard area for OS-specific
 	// purposes like signal handling. Used on Windows because
 	// it does not use a separate stack.
-#ifdef __WINDOWS__
+#ifdef GOOS_windows
 	StackSystem = 512 * sizeof(uintptr),
 #else
 	StackSystem = 0,
diff --git a/src/pkg/runtime/string.goc b/src/pkg/runtime/string.goc
index 0e2dddda34..7e1f8a1e8b 100644
--- a/src/pkg/runtime/string.goc
+++ b/src/pkg/runtime/string.goc
@@ -4,7 +4,7 @@
 
 package runtime
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 String	runtime·emptystring;
diff --git a/src/pkg/runtime/symtab.c b/src/pkg/runtime/symtab.c
index d0468c6dd4..6cd59136f4 100644
--- a/src/pkg/runtime/symtab.c
+++ b/src/pkg/runtime/symtab.c
@@ -13,9 +13,9 @@
 // and figure out exactly what we want.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
-#include "arch.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "arch_GOARCH.h"
 
 extern byte pclntab[], epclntab[], symtab[], esymtab[];
 
diff --git a/src/pkg/runtime/darwin/386/sys.s b/src/pkg/runtime/sys_darwin_386.s
similarity index 99%
rename from src/pkg/runtime/darwin/386/sys.s
rename to src/pkg/runtime/sys_darwin_386.s
index 426367b9e2..9a513468a0 100644
--- a/src/pkg/runtime/darwin/386/sys.s
+++ b/src/pkg/runtime/sys_darwin_386.s
@@ -6,7 +6,7 @@
 // See http://fxr.watson.org/fxr/source/bsd/kern/syscalls.c?v=xnu-1228
 // or /usr/include/sys/syscall.h (on a Mac) for system call numbers.
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 TEXT runtime·notok(SB),7,$0
 	MOVL	$0xf1, 0xf1
diff --git a/src/pkg/runtime/darwin/amd64/sys.s b/src/pkg/runtime/sys_darwin_amd64.s
similarity index 99%
rename from src/pkg/runtime/darwin/amd64/sys.s
rename to src/pkg/runtime/sys_darwin_amd64.s
index 5a504e3ecf..ac777656c5 100644
--- a/src/pkg/runtime/darwin/amd64/sys.s
+++ b/src/pkg/runtime/sys_darwin_amd64.s
@@ -11,7 +11,7 @@
 // The high 8 bits specify the kind of system call: 1=Mach, 2=BSD, 3=Machine-Dependent.
 //
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 // Exit the entire program (like C exit)
 TEXT runtime·exit(SB),7,$0
diff --git a/src/pkg/runtime/freebsd/386/sys.s b/src/pkg/runtime/sys_freebsd_386.s
similarity index 99%
rename from src/pkg/runtime/freebsd/386/sys.s
rename to src/pkg/runtime/sys_freebsd_386.s
index 41134ad61f..9833784efc 100644
--- a/src/pkg/runtime/freebsd/386/sys.s
+++ b/src/pkg/runtime/sys_freebsd_386.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "386/asm.h"
+#include "asm_386.h"
 	
 TEXT runtime·sys_umtx_op(SB),7,$-4
 	MOVL	$454, AX
diff --git a/src/pkg/runtime/freebsd/amd64/sys.s b/src/pkg/runtime/sys_freebsd_amd64.s
similarity index 99%
rename from src/pkg/runtime/freebsd/amd64/sys.s
rename to src/pkg/runtime/sys_freebsd_amd64.s
index bd63650236..991c33c825 100644
--- a/src/pkg/runtime/freebsd/amd64/sys.s
+++ b/src/pkg/runtime/sys_freebsd_amd64.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 	
 TEXT runtime·sys_umtx_op(SB),7,$0
 	MOVQ 8(SP), DI
diff --git a/src/pkg/runtime/linux/386/sys.s b/src/pkg/runtime/sys_linux_386.s
similarity index 99%
rename from src/pkg/runtime/linux/386/sys.s
rename to src/pkg/runtime/sys_linux_386.s
index d96c022d36..1763143f9e 100644
--- a/src/pkg/runtime/linux/386/sys.s
+++ b/src/pkg/runtime/sys_linux_386.s
@@ -6,7 +6,7 @@
 // System calls and other sys.stuff for 386, Linux
 //
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 TEXT runtime·exit(SB),7,$0
 	MOVL	$252, AX	// syscall number
diff --git a/src/pkg/runtime/linux/amd64/sys.s b/src/pkg/runtime/sys_linux_amd64.s
similarity index 99%
rename from src/pkg/runtime/linux/amd64/sys.s
rename to src/pkg/runtime/sys_linux_amd64.s
index 76bb48c75a..d55518686c 100644
--- a/src/pkg/runtime/linux/amd64/sys.s
+++ b/src/pkg/runtime/sys_linux_amd64.s
@@ -6,7 +6,7 @@
 // System calls and other sys.stuff for AMD64, Linux
 //
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 TEXT runtime·exit(SB),7,$0-8
 	MOVL	8(SP), DI
diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/sys_linux_arm.s
similarity index 99%
rename from src/pkg/runtime/linux/arm/sys.s
rename to src/pkg/runtime/sys_linux_arm.s
index 14ea337d02..d0b36dedf9 100644
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/sys_linux_arm.s
@@ -6,7 +6,7 @@
 // System calls and other sys.stuff for arm, Linux
 //
 
-#include "arm/asm.h"
+#include "asm_arm.h"
 
 // OABI
 //#define SYS_BASE 0x00900000
diff --git a/src/pkg/runtime/netbsd/386/sys.s b/src/pkg/runtime/sys_netbsd_386.s
similarity index 99%
rename from src/pkg/runtime/netbsd/386/sys.s
rename to src/pkg/runtime/sys_netbsd_386.s
index 20ed09a6b5..bcb4fc5e71 100644
--- a/src/pkg/runtime/netbsd/386/sys.s
+++ b/src/pkg/runtime/sys_netbsd_386.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 // Exit the entire program (like C exit)
 TEXT runtime·exit(SB),7,$-4
diff --git a/src/pkg/runtime/netbsd/amd64/sys.s b/src/pkg/runtime/sys_netbsd_amd64.s
similarity index 99%
rename from src/pkg/runtime/netbsd/amd64/sys.s
rename to src/pkg/runtime/sys_netbsd_amd64.s
index 693b51dff1..20817711fb 100644
--- a/src/pkg/runtime/netbsd/amd64/sys.s
+++ b/src/pkg/runtime/sys_netbsd_amd64.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 // int64 rfork_thread(int32 flags, void *stack, M *m, G *g, void (*fn)(void));
 TEXT runtime·rfork_thread(SB),7,$0
diff --git a/src/pkg/runtime/openbsd/386/sys.s b/src/pkg/runtime/sys_openbsd_386.s
similarity index 99%
rename from src/pkg/runtime/openbsd/386/sys.s
rename to src/pkg/runtime/sys_openbsd_386.s
index 2b1be7ee6b..ae3275c852 100644
--- a/src/pkg/runtime/openbsd/386/sys.s
+++ b/src/pkg/runtime/sys_openbsd_386.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 // Exit the entire program (like C exit)
 TEXT runtime·exit(SB),7,$-4
diff --git a/src/pkg/runtime/openbsd/amd64/sys.s b/src/pkg/runtime/sys_openbsd_amd64.s
similarity index 99%
rename from src/pkg/runtime/openbsd/amd64/sys.s
rename to src/pkg/runtime/sys_openbsd_amd64.s
index 9c2d403b25..f568ba4312 100644
--- a/src/pkg/runtime/openbsd/amd64/sys.s
+++ b/src/pkg/runtime/sys_openbsd_amd64.s
@@ -6,7 +6,7 @@
 // /usr/src/sys/kern/syscalls.master for syscall numbers.
 //
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 // int64 rfork_thread(int32 flags, void *stack, M *m, G *g, void (*fn)(void));
 TEXT runtime·rfork_thread(SB),7,$0
diff --git a/src/pkg/runtime/plan9/386/sys.s b/src/pkg/runtime/sys_plan9_386.s
similarity index 96%
rename from src/pkg/runtime/plan9/386/sys.s
rename to src/pkg/runtime/sys_plan9_386.s
index 97be276be6..8c773eee9d 100644
--- a/src/pkg/runtime/plan9/386/sys.s
+++ b/src/pkg/runtime/sys_plan9_386.s
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "defs.h"
-#include "386/asm.h"
+#include "defs_GOOS_GOARCH.h"
+#include "asm_386.h"
 
 // setldt(int entry, int address, int limit)
 TEXT runtime·setldt(SB),7,$0
diff --git a/src/pkg/runtime/windows/386/sys.s b/src/pkg/runtime/sys_windows_386.s
similarity index 99%
rename from src/pkg/runtime/windows/386/sys.s
rename to src/pkg/runtime/sys_windows_386.s
index 69b9b82e82..307b93d5c7 100644
--- a/src/pkg/runtime/windows/386/sys.s
+++ b/src/pkg/runtime/sys_windows_386.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "386/asm.h"
+#include "asm_386.h"
 
 // void runtime·asmstdcall(void *c);
 TEXT runtime·asmstdcall(SB),7,$0
diff --git a/src/pkg/runtime/windows/amd64/sys.s b/src/pkg/runtime/sys_windows_amd64.s
similarity index 99%
rename from src/pkg/runtime/windows/amd64/sys.s
rename to src/pkg/runtime/sys_windows_amd64.s
index a1e36fe132..508759ff8f 100644
--- a/src/pkg/runtime/windows/amd64/sys.s
+++ b/src/pkg/runtime/sys_windows_amd64.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-#include "amd64/asm.h"
+#include "asm_amd64.h"
 
 // maxargs should be divisible by 2, as Windows stack
 // must be kept 16-byte aligned on syscall entry.
diff --git a/src/pkg/runtime/windows/syscall.goc b/src/pkg/runtime/syscall_windows.goc
similarity index 99%
rename from src/pkg/runtime/windows/syscall.goc
rename to src/pkg/runtime/syscall_windows.goc
index d97a6cafd6..781ec908d0 100644
--- a/src/pkg/runtime/windows/syscall.goc
+++ b/src/pkg/runtime/syscall_windows.goc
@@ -4,7 +4,7 @@
 
 package syscall
 #include "runtime.h"
-#include "os.h"
+#include "os_GOOS.h"
 #include "cgocall.h"
 
 func loadlibrary(filename *uint16) (handle uintptr, err uintptr) {
diff --git a/src/pkg/runtime/darwin/thread.c b/src/pkg/runtime/thread_darwin.c
similarity index 99%
rename from src/pkg/runtime/darwin/thread.c
rename to src/pkg/runtime/thread_darwin.c
index 4665408725..12e79afda0 100644
--- a/src/pkg/runtime/darwin/thread.c
+++ b/src/pkg/runtime/thread_darwin.c
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 extern SigTab runtime·sigtab[];
diff --git a/src/pkg/runtime/freebsd/thread.c b/src/pkg/runtime/thread_freebsd.c
similarity index 98%
rename from src/pkg/runtime/freebsd/thread.c
rename to src/pkg/runtime/thread_freebsd.c
index 48532f6afc..779782ac96 100644
--- a/src/pkg/runtime/freebsd/thread.c
+++ b/src/pkg/runtime/thread_freebsd.c
@@ -2,8 +2,8 @@
 // license that can be found in the LICENSE file.`
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 extern SigTab runtime·sigtab[];
diff --git a/src/pkg/runtime/linux/thread.c b/src/pkg/runtime/thread_linux.c
similarity index 98%
rename from src/pkg/runtime/linux/thread.c
rename to src/pkg/runtime/thread_linux.c
index 5502bbbcab..d72e9cb435 100644
--- a/src/pkg/runtime/linux/thread.c
+++ b/src/pkg/runtime/thread_linux.c
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 extern SigTab runtime·sigtab[];
diff --git a/src/pkg/runtime/netbsd/thread.c b/src/pkg/runtime/thread_netbsd.c
similarity index 98%
rename from src/pkg/runtime/netbsd/thread.c
rename to src/pkg/runtime/thread_netbsd.c
index 3824a4f1b4..0aba02720e 100644
--- a/src/pkg/runtime/netbsd/thread.c
+++ b/src/pkg/runtime/thread_netbsd.c
@@ -2,8 +2,8 @@
 // license that can be found in the LICENSE file.`
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 enum
diff --git a/src/pkg/runtime/openbsd/thread.c b/src/pkg/runtime/thread_openbsd.c
similarity index 98%
rename from src/pkg/runtime/openbsd/thread.c
rename to src/pkg/runtime/thread_openbsd.c
index 55ca64b80b..e1cd5bf2e4 100644
--- a/src/pkg/runtime/openbsd/thread.c
+++ b/src/pkg/runtime/thread_openbsd.c
@@ -2,8 +2,8 @@
 // license that can be found in the LICENSE file.`
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 #include "stack.h"
 
 enum
diff --git a/src/pkg/runtime/plan9/thread.c b/src/pkg/runtime/thread_plan9.c
similarity index 98%
rename from src/pkg/runtime/plan9/thread.c
rename to src/pkg/runtime/thread_plan9.c
index 07edb717e4..a9b156d028 100644
--- a/src/pkg/runtime/plan9/thread.c
+++ b/src/pkg/runtime/thread_plan9.c
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "os.h"
-#include "arch.h"
+#include "os_GOOS.h"
+#include "arch_GOARCH.h"
 
 int8 *goos = "plan9";
 
diff --git a/src/pkg/runtime/windows/thread.c b/src/pkg/runtime/thread_windows.c
similarity index 99%
rename from src/pkg/runtime/windows/thread.c
rename to src/pkg/runtime/thread_windows.c
index dc7e06cd33..ad66c93a64 100644
--- a/src/pkg/runtime/windows/thread.c
+++ b/src/pkg/runtime/thread_windows.c
@@ -4,8 +4,8 @@
 
 #include "runtime.h"
 #include "type.h"
-#include "defs.h"
-#include "os.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
 
 #pragma dynimport runtime·CloseHandle CloseHandle "kernel32.dll"
 #pragma dynimport runtime·CreateEvent CreateEventA "kernel32.dll"
diff --git a/src/pkg/runtime/time.goc b/src/pkg/runtime/time.goc
index 8306e61358..a6b8352470 100644
--- a/src/pkg/runtime/time.goc
+++ b/src/pkg/runtime/time.goc
@@ -7,9 +7,9 @@
 package time
 
 #include "runtime.h"
-#include "defs.h"
-#include "os.h"
-#include "arch.h"
+#include "defs_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 static Timers timers;
diff --git a/src/pkg/runtime/amd64/traceback.c b/src/pkg/runtime/traceback_amd64.c
similarity index 99%
rename from src/pkg/runtime/amd64/traceback.c
rename to src/pkg/runtime/traceback_amd64.c
index fc9021e40e..fedda797c2 100644
--- a/src/pkg/runtime/amd64/traceback.c
+++ b/src/pkg/runtime/traceback_amd64.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 static uintptr isclosureentry(uintptr);
diff --git a/src/pkg/runtime/arm/traceback.c b/src/pkg/runtime/traceback_arm.c
similarity index 99%
rename from src/pkg/runtime/arm/traceback.c
rename to src/pkg/runtime/traceback_arm.c
index 0319cdc9b6..22e0bc3a66 100644
--- a/src/pkg/runtime/arm/traceback.c
+++ b/src/pkg/runtime/traceback_arm.c
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
-#include "arch.h"
+#include "arch_GOARCH.h"
 #include "malloc.h"
 
 void runtime·deferproc(void);
diff --git a/src/pkg/runtime/386/vlop.s b/src/pkg/runtime/vlop_386.s
similarity index 100%
rename from src/pkg/runtime/386/vlop.s
rename to src/pkg/runtime/vlop_386.s
diff --git a/src/pkg/runtime/arm/vlop.s b/src/pkg/runtime/vlop_arm.s
similarity index 100%
rename from src/pkg/runtime/arm/vlop.s
rename to src/pkg/runtime/vlop_arm.s
diff --git a/src/pkg/runtime/386/vlrt.c b/src/pkg/runtime/vlrt_386.c
similarity index 100%
rename from src/pkg/runtime/386/vlrt.c
rename to src/pkg/runtime/vlrt_386.c
diff --git a/src/pkg/runtime/arm/vlrt.c b/src/pkg/runtime/vlrt_arm.c
similarity index 100%
rename from src/pkg/runtime/arm/vlrt.c
rename to src/pkg/runtime/vlrt_arm.c