diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index d7179b3..75875d2 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -89,6 +89,8 @@
       MachineInstr *MI = &*I;
       ++I;
       if (MI->isImplicitDef()) {
+        if (MI->getOperand(0).getSubReg())
+          continue;
         unsigned Reg = MI->getOperand(0).getReg();
         ImpDefRegs.insert(Reg);
         if (TargetRegisterInfo::isPhysicalRegister(Reg)) {