diff --git a/include/llvm/CodeGen/LiveVariables.h b/include/llvm/CodeGen/LiveVariables.h
index efa5f3c869f..bbefbe08c08 100644
--- a/include/llvm/CodeGen/LiveVariables.h
+++ b/include/llvm/CodeGen/LiveVariables.h
@@ -189,6 +189,11 @@ public:
   /// the records for NewMI.
   void instructionChanged(MachineInstr *OldMI, MachineInstr *NewMI);
 
+  /// replaceKillInstruction - Update register kill info by replacing a kill
+  /// instruction with a new one.
+  void replaceKillInstruction(unsigned Reg, MachineInstr *OldMI,
+                              MachineInstr *NewMI);
+
   /// addVirtualRegisterKilled - Add information about the fact that the
   /// specified register is killed after being used by the specified
   /// instruction. If AddIfNotFound is true, add a implicit operand if it's
diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index ab73c97ec9e..ee4492b6ddc 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -684,6 +684,15 @@ void LiveVariables::instructionChanged(MachineInstr *OldMI,
   }
 }
 
+/// replaceKillInstruction - Update register kill info by replacing a kill
+/// instruction with a new one.
+void LiveVariables::replaceKillInstruction(unsigned Reg, MachineInstr *OldMI,
+                                           MachineInstr *NewMI) {
+  VarInfo &VI = getVarInfo(Reg);
+  if (VI.removeKill(OldMI))
+    VI.Kills.push_back(NewMI);   // Yes, there was a kill of it
+}
+
 /// removeVirtualRegistersKilled - Remove all killed info for the specified
 /// instruction.
 void LiveVariables::removeVirtualRegistersKilled(MachineInstr *MI) {
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index d2e5288d34b..480d6dd3897 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -375,10 +375,9 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
                   DOUT << "2addr: COMMUTED TO: " << *NewMI;
                   // If the instruction changed to commute it, update livevar.
                   if (NewMI != mi) {
-                    if (LV) {
+                    if (LV)
                       // Update live variables
-                      LV->instructionChanged(mi, NewMI); 
-                    }
+                      LV->replaceKillInstruction(regC, mi, NewMI);
                     
                     mbbi->insert(mi, NewMI);           // Insert the new inst
                     mbbi->erase(mi);                   // Nuke the old inst.