Index: compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
===================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
@@ -786,8 +786,25 @@
 }
 #endif
 
+// __cxa_guard_acquire and friends need to be intercepted in a special way -
+// regular interceptors will break statically-linked libstdc++. Linux
+// interceptors are especially defined as weak functions (so that they don't
+// cause link errors when user defines them as well). So they silently
+// auto-disable themselves when such symbol is already present in the binary. If
+// we link libstdc++ statically, it will bring own __cxa_guard_acquire which
+// will silently replace our interceptor.  That's why on Linux we simply export
+// these interceptors with INTERFACE_ATTRIBUTE.
+// On OS X, we don't support statically linking, so we just use a regular
+// interceptor.
+#if SANITIZER_MAC
+#define STDCXX_INTERCEPTOR TSAN_INTERCEPTOR
+#else
+#define STDCXX_INTERCEPTOR(rettype, name, ...) \
+  extern "C" rettype INTERFACE_ATTRIBUTE name(__VA_ARGS__)
+#endif
+
 // Used in thread-safe function static initialization.
-extern "C" int INTERFACE_ATTRIBUTE __cxa_guard_acquire(atomic_uint32_t *g) {
+STDCXX_INTERCEPTOR(int, __cxa_guard_acquire, atomic_uint32_t *g) {
   SCOPED_INTERCEPTOR_RAW(__cxa_guard_acquire, g);
   for (;;) {
     u32 cmp = atomic_load(g, memory_order_acquire);
@@ -803,13 +820,13 @@
   }
 }
 
-extern "C" void INTERFACE_ATTRIBUTE __cxa_guard_release(atomic_uint32_t *g) {
+STDCXX_INTERCEPTOR(void, __cxa_guard_release, atomic_uint32_t *g) {
   SCOPED_INTERCEPTOR_RAW(__cxa_guard_release, g);
   Release(thr, pc, (uptr)g);
   atomic_store(g, 1, memory_order_release);
 }
 
-extern "C" void INTERFACE_ATTRIBUTE __cxa_guard_abort(atomic_uint32_t *g) {
+STDCXX_INTERCEPTOR(void, __cxa_guard_abort, atomic_uint32_t *g) {
   SCOPED_INTERCEPTOR_RAW(__cxa_guard_abort, g);
   atomic_store(g, 0, memory_order_relaxed);
 }