diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 33ed4cc..a702c6c 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -502,7 +502,8 @@
       continue;
     if (!UI.getOperand().isKill())
       return 0;
-    assert(!KillMI && "More than one local kills?");
+    if (KillMI)
+      return 0;  // -O0 kill markers cannot be trusted?
     KillMI = UseMI;
   }