diff --git a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 0d8ee174d51..80990e5822b 100644
--- a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -175,6 +175,7 @@ static bool Is32BitMemOperand(const MCInst &MI, unsigned Op) {
 
 /// Is64BitMemOperand - Return true if the specified instruction has
 /// a 64-bit memory operand. Op specifies the operand # of the memoperand.
+#ifndef NDEBUG
 static bool Is64BitMemOperand(const MCInst &MI, unsigned Op) {
   const MCOperand &BaseReg  = MI.getOperand(Op+X86::AddrBaseReg);
   const MCOperand &IndexReg = MI.getOperand(Op+X86::AddrIndexReg);
@@ -186,6 +187,7 @@ static bool Is64BitMemOperand(const MCInst &MI, unsigned Op) {
     return true;
   return false;
 }
+#endif
 
 /// Is16BitMemOperand - Return true if the specified instruction has
 /// a 16-bit memory operand. Op specifies the operand # of the memoperand.