diff --git a/misc/cgo/testsanitizers/msan3.go b/misc/cgo/testsanitizers/msan3.go
new file mode 100644
index 0000000000..05b16ad184
--- /dev/null
+++ b/misc/cgo/testsanitizers/msan3.go
@@ -0,0 +1,32 @@
+// Copyright 2015 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.
+
+package main
+
+/*
+extern int *GoFn(void);
+
+// Yes, you can have definitions if you use //export, as long as they are weak.
+int f(void) __attribute__ ((weak));
+
+int f() {
+  int *p = GoFn();
+  if (*p != 12345)
+    return 0;
+  return 1;
+}
+*/
+import "C"
+
+//export GoFn
+func GoFn() *C.int {
+	i := C.int(12345)
+	return &i
+}
+
+func main() {
+	if r := C.f(); r != 1 {
+		panic(r)
+	}
+}
diff --git a/misc/cgo/testsanitizers/test.bash b/misc/cgo/testsanitizers/test.bash
index e200bcb80b..a4cff27701 100755
--- a/misc/cgo/testsanitizers/test.bash
+++ b/misc/cgo/testsanitizers/test.bash
@@ -17,7 +17,7 @@ export CC
 
 TMPDIR=${TMPDIR:-/tmp}
 echo > ${TMPDIR}/testsanitizers$$.c
-if $CC -fsanitize=memory -c ${TMPDIR}/testsanitizers$$.c 2>&1 | grep "unrecognized" >& /dev/null; then
+if $CC -fsanitize=memory -c ${TMPDIR}/testsanitizers$$.c -o ${TMPDIR}/testsanitizers$$.o 2>&1 | grep "unrecognized" >& /dev/null; then
   echo "skipping msan test: -fsanitize=memory not supported"
   rm -f ${TMPDIR}/testsanitizers$$.*
   exit 0
@@ -52,6 +52,11 @@ if ! go run -msan msan2.go; then
   status=1
 fi
 
+if ! go run -msan msan3.go; then
+  echo "FAIL: msan3"
+  status=1
+fi
+
 if go run -msan msan_fail.go 2>/dev/null; then
   echo "FAIL: msan_fail"
   status=1
diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
index 4ce778fc05..a01548a32f 100644
--- a/src/runtime/cgocall.go
+++ b/src/runtime/cgocall.go
@@ -266,6 +266,13 @@ func cgocallbackg1() {
 	if raceenabled {
 		racereleasemerge(unsafe.Pointer(&racecgosync))
 	}
+	if msanenabled {
+		// Tell msan that we wrote to the entire argument block.
+		// This tells msan that we set the results.
+		// Since we have already called the function it doesn't
+		// matter that we are writing to the non-result parameters.
+		msanwrite(cb.arg, cb.argsize)
+	}
 
 	// Do not unwind m->g0->sched.sp.
 	// Our caller, cgocallback, will do that.