diff --git a/llvm/lib/Target/Mips/MipsRegisterInfo.h b/llvm/lib/Target/Mips/MipsRegisterInfo.h
--- a/llvm/lib/Target/Mips/MipsRegisterInfo.h
+++ b/llvm/lib/Target/Mips/MipsRegisterInfo.h
@@ -69,6 +69,8 @@
   /// Debug information queries.
   Register getFrameRegister(const MachineFunction &MF) const override;
 
+  bool isConstantPhysReg(MCRegister PhysReg) const override;
+
   /// Return GPR register class.
   virtual const TargetRegisterClass *intRegClass(unsigned Size) const = 0;
 
diff --git a/llvm/lib/Target/Mips/MipsRegisterInfo.cpp b/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
--- a/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
@@ -318,3 +318,7 @@
   // sized objects.
   return MF.getRegInfo().canReserveReg(BP);
 }
+
+bool MipsRegisterInfo::isConstantPhysReg(MCRegister PhysReg) const {
+  return PhysReg == Mips::ZERO_64 || PhysReg == Mips::ZERO;
+}