Index: lib/Basic/Version.cpp
===================================================================
--- lib/Basic/Version.cpp
+++ lib/Basic/Version.cpp
@@ -111,6 +111,11 @@
       OS << LLVMRepo << ' ';
     OS << LLVMRev << ')';
   }
+
+  // Differentiate between the version with and without assertions.
+#ifndef NDEBUG
+  OS << " (+asserts)";
+#endif
   return OS.str();
 }