diff --git a/src/cmd/gc/Makefile b/src/cmd/gc/Makefile
index 4237e972a9f..e0d0f168873 100644
--- a/src/cmd/gc/Makefile
+++ b/src/cmd/gc/Makefile
@@ -26,7 +26,7 @@ OFILES=\
 	mparith1.$O\
 	mparith2.$O\
 	mparith3.$O\
-	sysimport.$O\
+	builtin.$O\
 	compat.$O\
 
 $(LIB): $(OFILES)
@@ -40,25 +40,11 @@ y.tab.h: $(YFILES)
 y.tab.c: y.tab.h
 	test -f y.tab.c && touch y.tab.c
 
-# the test here checks whether we have 6g at all.
-# if so, use it.  if not, just use the sysimport.c we have.
-# this happens on fresh perforce checkouts where
-# sysimport.c ends up with an older time stamp
-# than sys.go (or unsafe.go or mksys.c).
-sysimport.c:	sys.go unsafe.go mksys.c
-	if test -x $(BIN)/6g; then \
-		p4 open sysimport.c; \
-		gcc -o mksys mksys.c; \
-		6g sys.go; \
-		6g unsafe.go; \
-		./mksys sys >_sysimport.c && \
-		./mksys unsafe >>_sysimport.c && \
-		mv _sysimport.c sysimport.c; \
-	elif test -f sysimport.c; then \
-		touch sysimport.c; \
-	fi
+builtin.c:	sys.go unsafe.go mkbuiltin1.c mkbuiltin
+	mkbuiltin >builtin.c || \
+	(echo 'mkbuiltin failed; using bootstrap copy of builtin.c'; cp builtin.c.boot builtin.c)
 
 clean:
-	rm -f $(OFILES) *.6 enam.c 6.out a.out y.tab.h y.tab.c $(LIB) _sysimport.c
+	rm -f $(OFILES) *.6 enam.c 6.out a.out y.tab.h y.tab.c $(LIB) mkbuiltin1 builtin.c _builtin.c
 
 install: $(LIB)
diff --git a/src/cmd/gc/sysimport.c b/src/cmd/gc/builtin.c.boot
similarity index 100%
rename from src/cmd/gc/sysimport.c
rename to src/cmd/gc/builtin.c.boot
diff --git a/src/cmd/gc/mkbuiltin b/src/cmd/gc/mkbuiltin
new file mode 100755
index 00000000000..8148120e0dc
--- /dev/null
+++ b/src/cmd/gc/mkbuiltin
@@ -0,0 +1,31 @@
+#!/bin/sh
+# Copyright 2009 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+set -e
+gcc -o mkbuiltin1 mkbuiltin1.c
+6g sys.go
+6g unsafe.go
+rm -f _builtin.c
+./mkbuiltin1 sys >_builtin.c
+./mkbuiltin1 unsafe >>_builtin.c
+
+# If _builtin.c has changed vs builtin.c.boot,
+# check in the new change if being run by
+# one of the people who tends to work on
+# the compiler.  This makes sure that changes
+# don't get forgotten, without causing problems
+# in end user Go repositories.
+case "$USER" in
+ken | r | rsc)
+	if ! cmp _builtin.c builtin.c.boot
+	then
+		p4 open builtin.c.boot
+		cp _builtin.c builtin.c.boot
+	fi
+esac
+
+cat _builtin.c
+rm -f _builtin.c
+
diff --git a/src/cmd/gc/mksys.c b/src/cmd/gc/mkbuiltin1.c
similarity index 90%
rename from src/cmd/gc/mksys.c
rename to src/cmd/gc/mkbuiltin1.c
index 25593d41529..22ef468f311 100644
--- a/src/cmd/gc/mksys.c
+++ b/src/cmd/gc/mkbuiltin1.c
@@ -1,8 +1,8 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Extract import data from sys.6 and generate C string version.
+// Compile .go file, import data from .6 file, and generate C string version.
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -18,7 +18,7 @@ main(int argc, char **argv)
 	char buf[1024], initfunc[1024], *p, *q;
 
 	if(argc != 2) {
-		fprintf(stderr, "usage: sys sys\n");
+		fprintf(stderr, "usage: mkbuiltin1 sys\n");
 		fprintf(stderr, "in file $1.6 s/PACKAGE/$1/\n");
 		exit(1);
 	}