Index: lib/tsan/CMakeLists.txt
===================================================================
--- lib/tsan/CMakeLists.txt
+++ lib/tsan/CMakeLists.txt
@@ -118,7 +118,7 @@
                 RTUbsan
     CFLAGS ${TSAN_RTL_CFLAGS}
     LINK_FLAGS ${SANITIZER_COMMON_LINK_FLAGS} ${WEAK_SYMBOL_LINK_FLAGS}
-    LINK_LIBS ${TSAN_LINK_LIBS}
+    LINK_LIBS ${TSAN_LINK_LIBS} objc
     PARENT_TARGET tsan)
   add_compiler_rt_object_libraries(RTTsan_dynamic
     OS ${TSAN_SUPPORTED_OS}
Index: lib/tsan/rtl/tsan_interceptors_mac.cc
===================================================================
--- lib/tsan/rtl/tsan_interceptors_mac.cc
+++ lib/tsan/rtl/tsan_interceptors_mac.cc
@@ -294,6 +294,19 @@
 
 #endif  // #if defined(__has_include) && __has_include(<xpc/xpc.h>)
 
+TSAN_INTERCEPTOR(int, objc_sync_enter, void *obj) {
+  SCOPED_TSAN_INTERCEPTOR(objc_sync_enter, obj);
+  int result = REAL(objc_sync_enter)(obj);
+  if (obj) Acquire(thr, pc, (uptr)obj);
+  return result;
+}
+
+TSAN_INTERCEPTOR(int, objc_sync_exit, void *obj) {
+  SCOPED_TSAN_INTERCEPTOR(objc_sync_enter, obj);
+  if (obj) Release(thr, pc, (uptr)obj);
+  return REAL(objc_sync_exit)(obj);
+}
+
 // On macOS, libc++ is always linked dynamically, so intercepting works the
 // usual way.
 #define STDCXX_INTERCEPTOR TSAN_INTERCEPTOR