diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index 3583a9b71b3..9958d7daada 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -1557,7 +1557,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) {
     if (Succ == FallThrough)
       continue;
     FromBBI.BB->removeSuccessor(Succ);
-    if (AddEdges)
+    if (AddEdges && !ToBBI.BB->isSuccessor(Succ))
       ToBBI.BB->addSuccessor(Succ);
   }