diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index c704432..96bc3ef 100644
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -229,6 +229,8 @@
     return RValue::get(Builder.CreateCall(F));
   }
   case Builtin::BI__builtin_unreachable: {
+    if (CatchUndefined && HaveInsertPoint())
+      EmitBranch(getTrapBB());
     Value *V = Builder.CreateUnreachable();
     Builder.ClearInsertionPoint();
     return RValue::get(V);