diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 1536a64..cb71f1a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -5210,8 +5210,7 @@
   // Emit constants only once even if used by multiple PHI nodes.
   std::map<Constant*, unsigned> ConstantsOut;
   
-  // Vector bool would be better, but vector<bool> is really slow.
-  std::vector<unsigned char> SuccsHandled;
+  BitVector SuccsHandled;
   if (TI->getNumSuccessors())
     SuccsHandled.resize(BB->getParent()->getNumBlockIDs());