diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index 7351119..e78ca9b 100644
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -602,9 +602,7 @@
     // Check Live Variables.
     if (MI->isDebugValue()) {
       // Liveness checks are not valid for debug values.
-    } else if (MO->isUndef()) {
-      // An <undef> doesn't refer to any register, so just skip it.
-    } else if (MO->isUse()) {
+    } else if (MO->isUse() && !MO->isUndef()) {
       regsLiveInButUnused.erase(Reg);
 
       bool isKill = false;
@@ -675,8 +673,7 @@
             MInfo.vregsLiveIn.insert(std::make_pair(Reg, MI));
         }
       }
-    } else {
-      assert(MO->isDef());
+    } else if (MO->isDef()) {
       // Register defined.
       // TODO: verify that earlyclobber ops are not used.
       if (MO->isDead())