diff --git a/lib/Basic/TargetInfo.cpp b/lib/Basic/TargetInfo.cpp
index 6c3389c..4ce32a9 100644
--- a/lib/Basic/TargetInfo.cpp
+++ b/lib/Basic/TargetInfo.cpp
@@ -145,10 +145,10 @@
     switch (*Name) {
     default:
       if (!validateAsmConstraint(*Name, info)) {
-        // FIXME: This assert is in place temporarily 
+        // FIXME: We temporarily return false
         // so we can add more constraints as we hit it.
         // Eventually, an unknown constraint should just be treated as 'g'.
-        assert(0 && "Unknown output constraint type!");
+        return false;
       }
     case '&': // early clobber.
       break;