diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -443,7 +443,6 @@
   /// getSubtarget - Return the subtarget for which this machine code is being
   /// compiled.
   const TargetSubtargetInfo &getSubtarget() const { return *STI; }
-  void setSubtarget(const TargetSubtargetInfo *ST) { STI = ST; }
 
   /// getSubtarget - This method returns a pointer to the specified type of
   /// TargetSubtargetInfo.  In debug builds, it verifies that the object being
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.h b/llvm/lib/Target/Mips/MipsTargetMachine.h
--- a/llvm/lib/Target/Mips/MipsTargetMachine.h
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.h
@@ -29,7 +29,7 @@
   std::unique_ptr<TargetLoweringObjectFile> TLOF;
   // Selected ABI
   MipsABIInfo ABI;
-  MipsSubtarget *Subtarget;
+  const MipsSubtarget *Subtarget;
   MipsSubtarget DefaultSubtarget;
   MipsSubtarget NoMips16Subtarget;
   MipsSubtarget Mips16Subtarget;
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -204,8 +204,7 @@
 void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
   LLVM_DEBUG(dbgs() << "resetSubtarget\n");
 
-  Subtarget = const_cast<MipsSubtarget *>(getSubtargetImpl(MF->getFunction()));
-  MF->setSubtarget(Subtarget);
+  Subtarget = &MF->getSubtarget<MipsSubtarget>();
 }
 
 namespace {