diff --git a/include/llvm/CodeGen/LiveVariables.h b/include/llvm/CodeGen/LiveVariables.h
index 36536a14ee8..8938330fad6 100644
--- a/include/llvm/CodeGen/LiveVariables.h
+++ b/include/llvm/CodeGen/LiveVariables.h
@@ -83,6 +83,10 @@ public:
     ///
     BitVector AliveBlocks;
 
+    /// UsedBlocks - Set of blocks of which this value is actually used. This
+    /// is a bit set which uses the basic block number as an index.
+    BitVector UsedBlocks;
+
     /// NumUses - Number of uses of this register across the entire function.
     ///
     unsigned NumUses;