Index: llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -624,11 +624,15 @@
   case AArch64::MOVi64imm:
     return canBeExpandedToORR(MI, 64);
 
-  // It is cheap to move #0 to float registers if the subtarget has 
-  // ZeroCycleZeroing feature.
+  // It is cheap to zero out registers if the subtarget has ZeroCycleZeroing
+  // feature.
   case AArch64::FMOVS0:
   case AArch64::FMOVD0:
     return Subtarget.hasZeroCycleZeroing();
+  case TargetOpcode::COPY:
+    return (Subtarget.hasZeroCycleZeroing() &&
+            (MI.getOperand(1).getReg() == AArch64::WZR ||
+             MI.getOperand(1).getReg() == AArch64::XZR));
   }
 
   llvm_unreachable("Unknown opcode to check as cheap as a move!");