1 files changed, 5 insertions, 1 deletions
diff --git a/llvm/lib/Target/X86/X86FlagsCopyLowering.cpp b/llvm/lib/Target/X86/X86FlagsCopyLowering.cpp
index 2d9886e3f238..f24dbcfe972d 100644
--- a/llvm/lib/Target/X86/X86FlagsCopyLowering.cpp
+++ b/llvm/lib/Target/X86/X86FlagsCopyLowering.cpp
@@ -964,7 +964,11 @@ void X86FlagsCopyLoweringPass::rewriteSetCC(MachineBasicBlock &TestMBB,
   if (!SetCCI.mayStore()) {
     assert(SetCCI.getOperand(0).isReg() &&
            "Cannot have a non-register defined operand to SETcc!");
-    MRI->replaceRegWith(SetCCI.getOperand(0).getReg(), CondReg);
+    Register OldReg = SetCCI.getOperand(0).getReg();
+    // Drop Kill flags on the old register before replacing. CondReg may have
+    // a longer live range.
+    MRI->clearKillFlags(OldReg);
+    MRI->replaceRegWith(OldReg, CondReg);
     SetCCI.eraseFromParent();
     return;
   }