diff --git a/misc/cgo/testsanitizers/test.bash b/misc/cgo/testsanitizers/test.bash
index feacd89c27..69caa39b15 100755
--- a/misc/cgo/testsanitizers/test.bash
+++ b/misc/cgo/testsanitizers/test.bash
@@ -15,35 +15,36 @@ if test -x "$(type -p clang)"; then
 fi
 export CC
 
+msan=yes
+
 TMPDIR=${TMPDIR:-/tmp}
 echo > ${TMPDIR}/testsanitizers$$.c
 if $CC -fsanitize=memory -c ${TMPDIR}/testsanitizers$$.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
+  echo "skipping msan tests: -fsanitize=memory not supported"
+  msan=no
 fi
 rm -f ${TMPDIR}/testsanitizers$$.*
 
 # The memory sanitizer in versions of clang before 3.6 don't work with Go.
-if $CC --version | grep clang >& /dev/null; then
+if test "$msan" = "yes" && $CC --version | grep clang >& /dev/null; then
   ver=$($CC --version | sed -e 's/.* version \([0-9.-]*\).*/\1/')
   major=$(echo $ver | sed -e 's/\([0-9]*\).*/\1/')
   minor=$(echo $ver | sed -e 's/[0-9]*\.\([0-9]*\).*/\1/')
   if test "$major" -lt 3 || test "$major" -eq 3 -a "$minor" -lt 6; then
-    echo "skipping msan test; clang version $major.$minor (older than 3.6)"
-    exit 0
+    echo "skipping msan tests: clang version $major.$minor (older than 3.6)"
+    msan=no
   fi
 
   # Clang before 3.8 does not work with Linux at or after 4.1.
   # golang.org/issue/12898.
-  if test "$major" -lt 3 || test "$major" -eq 3 -a "$minor" -lt 8; then
+  if test "$msan" = "yes" -a "$major" -lt 3 || test "$major" -eq 3 -a "$minor" -lt 8; then
     if test "$(uname)" = Linux; then
       linuxver=$(uname -r)
       linuxmajor=$(echo $linuxver | sed -e 's/\([0-9]*\).*/\1/')
       linuxminor=$(echo $linuxver | sed -e 's/[0-9]*\.\([0-9]*\).*/\1/')
       if test "$linuxmajor" -gt 4 || test "$linuxmajor" -eq 4 -a "$linuxminor" -ge 1; then
-        echo "skipping msan test; clang version $major.$minor (older than 3.8) incompatible with linux version $linuxmajor.$linuxminor (4.1 or newer)"
-        exit 0
+        echo "skipping msan tests: clang version $major.$minor (older than 3.8) incompatible with linux version $linuxmajor.$linuxminor (4.1 or newer)"
+	msan=no
       fi
     fi
   fi
@@ -51,39 +52,75 @@ fi
 
 status=0
 
-if ! go build -msan std; then
-  echo "FAIL: build -msan std"
-  status=1
+if test "$msan" = "yes"; then
+    if ! go build -msan std; then
+	echo "FAIL: build -msan std"
+	status=1
+    fi
+
+    if ! go run -msan msan.go; then
+	echo "FAIL: msan"
+	status=1
+    fi
+
+    if ! CGO_LDFLAGS="-fsanitize=memory" CGO_CPPFLAGS="-fsanitize=memory" go run -msan -a msan2.go; then
+	echo "FAIL: msan2 with -fsanitize=memory"
+	status=1
+    fi
+
+    if ! go run -msan -a msan2.go; then
+	echo "FAIL: msan2"
+	status=1
+    fi
+
+    if ! go run -msan msan3.go; then
+	echo "FAIL: msan3"
+	status=1
+    fi
+
+    if ! go run -msan msan4.go; then
+	echo "FAIL: msan4"
+	status=1
+    fi
+
+    if go run -msan msan_fail.go 2>/dev/null; then
+	echo "FAIL: msan_fail"
+	status=1
+    fi
 fi
 
-if ! go run -msan msan.go; then
-  echo "FAIL: msan"
-  status=1
-fi
+tsan=yes
 
-if ! CGO_LDFLAGS="-fsanitize=memory" CGO_CPPFLAGS="-fsanitize=memory" go run -msan -a msan2.go; then
-  echo "FAIL: msan2 with -fsanitize=memory"
-  status=1
+TMPDIR=${TMPDIR:-/tmp}
+echo > ${TMPDIR}/testsanitizers$$.c
+if $CC -fsanitize=thread -c ${TMPDIR}/testsanitizers$$.c -o ${TMPDIR}/testsanitizers$$.o 2>&1 | grep "unrecognized" >& /dev/null; then
+  echo "skipping tsan tests: -fsanitize=thread not supported"
+  tsan=no
 fi
+rm -f ${TMPDIR}/testsanitizers$$.*
 
-if ! go run -msan -a msan2.go; then
-  echo "FAIL: msan2"
-  status=1
-fi
+if test "$tsan" = "yes"; then
+    err=${TMPDIR}/tsanerr$$.out
 
-if ! go run -msan msan3.go; then
-  echo "FAIL: msan3"
-  status=1
-fi
+    if ! go run tsan.go 2>$err; then
+	echo "FAIL: tsan"
+	status=1
+    elif grep -i warning $err >/dev/null 2>&1; then
+	cat $err
+	echo "FAIL: tsan"
+	status=1
+    fi
 
-if ! go run -msan msan4.go; then
-  echo "FAIL: msan4"
-  status=1
-fi
+    if ! go run tsan2.go 2>$err; then
+	echo "FAIL: tsan2"
+	status=1
+    elif grep -i warning $err >/dev/null 2>&1; then
+	cat $err
+	echo "FAIL: tsan2"
+	status=1
+    fi
 
-if go run -msan msan_fail.go 2>/dev/null; then
-  echo "FAIL: msan_fail"
-  status=1
+    rm -f $err
 fi
 
 exit $status
diff --git a/misc/cgo/testsanitizers/tsan.go b/misc/cgo/testsanitizers/tsan.go
new file mode 100644
index 0000000000..9e0951c914
--- /dev/null
+++ b/misc/cgo/testsanitizers/tsan.go
@@ -0,0 +1,44 @@
+// 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
+
+// This program produced false race reports when run under the C/C++
+// ThreadSanitizer, as it did not understand the synchronization in
+// the Go code.
+
+/*
+#cgo CFLAGS: -fsanitize=thread
+#cgo LDFLAGS: -fsanitize=thread
+
+int val;
+
+int getVal() {
+	return val;
+}
+
+void setVal(int i) {
+	val = i;
+}
+*/
+import "C"
+
+import (
+	"runtime"
+)
+
+func main() {
+	runtime.LockOSThread()
+	C.setVal(1)
+	c := make(chan bool)
+	go func() {
+		runtime.LockOSThread()
+		C.setVal(2)
+		c <- true
+	}()
+	<-c
+	if v := C.getVal(); v != 2 {
+		panic(v)
+	}
+}
diff --git a/misc/cgo/testsanitizers/tsan2.go b/misc/cgo/testsanitizers/tsan2.go
new file mode 100644
index 0000000000..78234a0799
--- /dev/null
+++ b/misc/cgo/testsanitizers/tsan2.go
@@ -0,0 +1,55 @@
+// 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
+
+// This program produced false race reports when run under the C/C++
+// ThreadSanitizer, as it did not understand the synchronization in
+// the Go code.
+
+/*
+#cgo CFLAGS: -fsanitize=thread
+#cgo LDFLAGS: -fsanitize=thread
+
+extern void GoRun(void);
+
+// Yes, you can have definitions if you use //export, as long as they are weak.
+
+int val __attribute__ ((weak));
+
+int run(void) __attribute__ ((weak));
+
+int run() {
+	val = 1;
+	GoRun();
+	return val;
+}
+
+void setVal(int) __attribute__ ((weak));
+
+void setVal(int i) {
+	val = i;
+}
+*/
+import "C"
+
+import "runtime"
+
+//export GoRun
+func GoRun() {
+	runtime.LockOSThread()
+	c := make(chan bool)
+	go func() {
+		runtime.LockOSThread()
+		C.setVal(2)
+		c <- true
+	}()
+	<-c
+}
+
+func main() {
+	if v := C.run(); v != 2 {
+		panic(v)
+	}
+}
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index ca0ec0aaa2..aafe6a8be5 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -507,6 +507,7 @@ func (p *Package) writeOutput(f *File, srcfile string) {
 	// Gcc output starts with the preamble.
 	fmt.Fprintf(fgcc, "%s\n", f.Preamble)
 	fmt.Fprintf(fgcc, "%s\n", gccProlog)
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, key := range nameKeys(f.Name) {
 		n := f.Name[key]
@@ -573,6 +574,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		// Save the stack top for use below.
 		fmt.Fprintf(fgcc, "\tchar *stktop = _cgo_topofstack();\n")
 	}
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
 	fmt.Fprintf(fgcc, "\t")
 	if t := n.FuncType.Result; t != nil {
 		fmt.Fprintf(fgcc, "__typeof__(a->r) r = ")
@@ -598,6 +600,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		fmt.Fprintf(fgcc, "a->p%d", i)
 	}
 	fmt.Fprintf(fgcc, ");\n")
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
 	if n.FuncType.Result != nil {
 		// The cgo call may have caused a stack copy (via a callback).
 		// Adjust the return value pointer appropriately.
@@ -636,9 +639,13 @@ func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
 	}
 	fmt.Fprintf(fgcc, ")\n")
 	fmt.Fprintf(fgcc, "{\n")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "\t%s r;\n", t.C.String())
+	}
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
 	fmt.Fprintf(fgcc, "\t")
 	if t := n.FuncType.Result; t != nil {
-		fmt.Fprintf(fgcc, "return ")
+		fmt.Fprintf(fgcc, "r = ")
 		// Cast to void* to avoid warnings due to omitted qualifiers.
 		if c := t.C.String(); c[len(c)-1] == '*' {
 			fmt.Fprintf(fgcc, "(void*)")
@@ -656,6 +663,16 @@ func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
 		fmt.Fprintf(fgcc, "p%d", i)
 	}
 	fmt.Fprintf(fgcc, ");\n")
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "\treturn ")
+		// Cast to void* to avoid warnings due to omitted qualifiers
+		// and explicit incompatible struct types.
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprintf(fgcc, "(void*)")
+		}
+		fmt.Fprintf(fgcc, "r;\n")
+	}
 	fmt.Fprintf(fgcc, "}\n")
 	fmt.Fprintf(fgcc, "\n")
 }
@@ -683,6 +700,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 
 	fmt.Fprintf(fgcc, "extern void crosscall2(void (*fn)(void *, int), void *, int);\n")
 	fmt.Fprintf(fgcc, "extern void _cgo_wait_runtime_init_done();\n\n")
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, exp := range p.ExpFunc {
 		fn := exp.Func
@@ -798,7 +816,9 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 			func(i int, aname string, atype ast.Expr) {
 				fmt.Fprintf(fgcc, "\ta.p%d = p%d;\n", i, i)
 			})
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
 		fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &a, %d);\n", cPrefix, exp.ExpName, off)
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
 		if gccResult != "void" {
 			if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
 				fmt.Fprintf(fgcc, "\treturn a.r0;\n")
@@ -915,6 +935,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
 
 	fmt.Fprintf(fgcc, "%s\n", gccgoExportFileProlog)
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, exp := range p.ExpFunc {
 		fn := exp.Func
@@ -985,11 +1006,15 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 
 		fmt.Fprint(fgcc, "\n")
 		fmt.Fprintf(fgcc, "%s %s %s {\n", cRet, exp.ExpName, cParams)
+		if resultCount > 0 {
+			fmt.Fprintf(fgcc, "\t%s r;\n", cRet)
+		}
 		fmt.Fprintf(fgcc, "\tif(_cgo_wait_runtime_init_done)\n")
 		fmt.Fprintf(fgcc, "\t\t_cgo_wait_runtime_init_done();\n")
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
 		fmt.Fprint(fgcc, "\t")
 		if resultCount > 0 {
-			fmt.Fprint(fgcc, "return ")
+			fmt.Fprint(fgcc, "r = ")
 		}
 		fmt.Fprintf(fgcc, "%s(", goName)
 		if fn.Recv != nil {
@@ -1003,6 +1028,10 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 				fmt.Fprintf(fgcc, "p%d", i)
 			})
 		fmt.Fprint(fgcc, ");\n")
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
+		if resultCount > 0 {
+			fmt.Fprint(fgcc, "\treturn r;\n")
+		}
 		fmt.Fprint(fgcc, "}\n")
 
 		// Dummy declaration for _cgo_main.c
@@ -1257,6 +1286,31 @@ extern char* _cgo_topofstack(void);
 #include <string.h>
 `
 
+// Prologue defining TSAN functions in C.
+const tsanProlog = `
+#define _cgo_tsan_acquire()
+#define _cgo_tsan_release()
+#if defined(__has_feature)
+#if __has_feature(thread_sanitizer)
+#undef _cgo_tsan_acquire
+#undef _cgo_tsan_release
+
+long long _cgo_sync __attribute__ ((common));
+
+extern void __tsan_acquire(void*);
+extern void __tsan_release(void*);
+
+static void _cgo_tsan_acquire() {
+	__tsan_acquire(&_cgo_sync);
+}
+
+static void _cgo_tsan_release() {
+	__tsan_release(&_cgo_sync);
+}
+#endif
+#endif
+`
+
 const builtinProlog = `
 #include <stddef.h> /* for ptrdiff_t and size_t below */
 
@@ -1290,8 +1344,10 @@ func _cgoCheckResult(interface{})
 `
 
 const gccgoGoProlog = `
+//extern runtime.cgoCheckPointer
 func _cgoCheckPointer(interface{}, ...interface{}) interface{}
 
+//extern runtime.cgoCheckResult
 func _cgoCheckResult(interface{})
 `