diff --git a/llvm/lib/Target/M68k/M68kSubtarget.h b/llvm/lib/Target/M68k/M68kSubtarget.h
--- a/llvm/lib/Target/M68k/M68kSubtarget.h
+++ b/llvm/lib/Target/M68k/M68kSubtarget.h
@@ -18,7 +18,6 @@
 #include "M68kISelLowering.h"
 #include "M68kInstrInfo.h"
 
-#include "llvm/ADT/BitVector.h"
 #include "llvm/CodeGen/GlobalISel/CallLowering.h"
 #include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
@@ -52,7 +51,7 @@
   enum SubtargetEnum { M00, M10, M20, M30, M40, M60 };
   SubtargetEnum SubtargetKind = M00;
 
-  BitVector UserReservedRegister;
+  std::bitset<M68k::NUM_TARGET_REGS> UserReservedRegister;
 
   InstrItineraryData InstrItins;
 
diff --git a/llvm/lib/Target/M68k/M68kSubtarget.cpp b/llvm/lib/Target/M68k/M68kSubtarget.cpp
--- a/llvm/lib/Target/M68k/M68kSubtarget.cpp
+++ b/llvm/lib/Target/M68k/M68kSubtarget.cpp
@@ -50,8 +50,7 @@
 
 M68kSubtarget::M68kSubtarget(const Triple &TT, StringRef CPU, StringRef FS,
                              const M68kTargetMachine &TM)
-    : M68kGenSubtargetInfo(TT, CPU, /*TuneCPU*/ CPU, FS),
-      UserReservedRegister(M68k::NUM_TARGET_REGS), TM(TM), TSInfo(),
+    : M68kGenSubtargetInfo(TT, CPU, /*TuneCPU*/ CPU, FS), TM(TM), TSInfo(),
       InstrInfo(initializeSubtargetDependencies(CPU, TT, FS, TM)),
       FrameLowering(*this, this->getStackAlignment()), TLInfo(TM, *this),
       TargetTriple(TT) {
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -107,7 +107,7 @@
   MVT XLenVT = MVT::i32;
   uint8_t MaxInterleaveFactor = 2;
   RISCVABI::ABI TargetABI = RISCVABI::ABI_Unknown;
-  BitVector UserReservedRegister;
+  std::bitset<RISCV::NUM_TARGET_REGS> UserReservedRegister;
   RISCVFrameLowering FrameLowering;
   RISCVInstrInfo InstrInfo;
   RISCVRegisterInfo RegInfo;
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.cpp b/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
@@ -91,8 +91,8 @@
                                StringRef TuneCPU, StringRef FS,
                                StringRef ABIName, const TargetMachine &TM)
     : RISCVGenSubtargetInfo(TT, CPU, TuneCPU, FS),
-      UserReservedRegister(RISCV::NUM_TARGET_REGS),
-      FrameLowering(initializeSubtargetDependencies(TT, CPU, TuneCPU, FS, ABIName)),
+      FrameLowering(
+          initializeSubtargetDependencies(TT, CPU, TuneCPU, FS, ABIName)),
       InstrInfo(*this), RegInfo(getHwMode()), TLInfo(TM, *this) {
   CallLoweringInfo.reset(new RISCVCallLowering(*getTargetLowering()));
   Legalizer.reset(new RISCVLegalizerInfo(*this));