diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index e3df2e4..d7179b3 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -205,10 +205,9 @@
       // Process each use instruction once.
       for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
              UE = mri_->use_end(); UI != UE; ++UI) {
-        MachineInstr *RMI = &*UI;
-        MachineBasicBlock *RMBB = RMI->getParent();
-        if (RMBB == MBB)
+        if (UI.getOperand().isUndef())
           continue;
+        MachineInstr *RMI = &*UI;
         if (ModInsts.insert(RMI))
           RUses.push_back(RMI);
       }