diff --git a/llvm/lib/CodeGen/LiveVariables.cpp b/llvm/lib/CodeGen/LiveVariables.cpp
--- a/llvm/lib/CodeGen/LiveVariables.cpp
+++ b/llvm/lib/CodeGen/LiveVariables.cpp
@@ -828,7 +828,8 @@
          BBE = SuccBB->end();
        BBI != BBE && BBI->isPHI(); ++BBI) {
     for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
-      if (BBI->getOperand(i + 1).getMBB() == BB)
+      if (BBI->getOperand(i + 1).getMBB() == BB &&
+          BBI->getOperand(i).readsReg())
         getVarInfo(BBI->getOperand(i).getReg())
           .AliveBlocks.set(NumNew);
   }