Index: lib/Support/Unix/Signals.inc
===================================================================
--- lib/Support/Unix/Signals.inc
+++ lib/Support/Unix/Signals.inc
@@ -149,11 +149,7 @@
 #endif
 
 static void RegisterHandlers() {
-  // We need to dereference the signals mutex during handler registration so
-  // that we force its construction. This is to prevent the first use being
-  // during handling an actual signal because you can't safely call new in a
-  // signal handler.
-  *SignalsMutex;
+  sys::SmartScopedLock<true> Guard(*SignalsMutex);
 
   // If the handlers are already registered, we're done.
   if (NumRegisteredSignals != 0) return;