--- a/mfbt/Assertions.h
+++ b/mfbt/Assertions.h
@@ -210,17 +210,24 @@ MOZ_ReportCrash(const char* aStr, const 
     * compiler doesn't hassle us to provide a return statement after a
     * MOZ_REALLY_CRASH() call.
     *
     * (Technically these are Windows requirements, not MSVC requirements.  But
     * practically you need MSVC for debugging, and we only ship builds created
     * by MSVC, so doing it this way reduces complexity.)
     */
 
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Winvalid-noreturn"
+#endif
 __declspec(noreturn) __inline void MOZ_NoReturn() {}
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 
 #  ifdef __cplusplus
 #    define MOZ_REALLY_CRASH() \
        do { \
          ::__debugbreak(); \
          *((volatile int*) NULL) = __LINE__; \
          ::TerminateProcess(::GetCurrentProcess(), 3); \
          ::MOZ_NoReturn(); \