diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index d889422992b..719bc8a34f8 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -39,6 +39,10 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) {
   
   // Can't merge if there are multiple predecessors.
   if (!PredBB) return false;
+  // Don't break self-loops.
+  if (PredBB == BB) return false;
+  // Don't break invokes.
+  if (isa<InvokeInst>(PredBB->getTerminator())) return false;
   
   succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
   BasicBlock* OnlySucc = BB;