diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 519990e..ca8ecff 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -556,17 +556,21 @@
       if (MI->isPHI())
         NumOperandsToProcess = 1;
 
+      // Clear kill and dead markers. LV will recompute them.
       SmallVector<unsigned, 4> UseRegs;
       SmallVector<unsigned, 4> DefRegs;
       for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
-        const MachineOperand &MO = MI->getOperand(i);
+        MachineOperand &MO = MI->getOperand(i);
         if (!MO.isReg() || MO.getReg() == 0)
           continue;
         unsigned MOReg = MO.getReg();
-        if (MO.isUse())
+        if (MO.isUse()) {
+          MO.setIsKill(false);
           UseRegs.push_back(MOReg);
-        if (MO.isDef())
+        } else /*MO.isDef()*/ {
+          MO.setIsDead(false);
           DefRegs.push_back(MOReg);
+        }
       }
 
       // Process all uses.