diff --git a/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp b/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp
diff --git a/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h b/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h
@@ -22,6 +22,7 @@
 #include "MCTargetDesc/AArch64MCTargetDesc.h" // For AArch64::X0 and friends.
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/ErrorHandling.h"
 
 namespace llvm {
@@ -280,16 +281,22 @@ struct AArch64NamedImmMapper {
   struct Mapping {
     const char *Name;
     uint32_t Value;
-    uint64_t FeatureBitSet;  // Set of features this mapping is available for
+    // Set of features this mapping is available for
     // Zero value of FeatureBitSet means the mapping is always available
+    FeatureBitset FeatureBitSet;
 
-    bool isNameEqual(std::string Other, uint64_t FeatureBits=~0ULL) const {
-      if (FeatureBitSet && !(FeatureBitSet & FeatureBits))
+    bool isNameEqual(std::string Other, 
+                     const FeatureBitset& FeatureBits) const {
+      if (FeatureBitSet.any() && 
+          (FeatureBitSet & FeatureBits).none())
         return false;
       return Name == Other;
     }
-    bool isValueEqual(uint32_t Other, uint64_t FeatureBits=~0ULL) const {
-      if (FeatureBitSet && !(FeatureBitSet & FeatureBits))
+
+    bool isValueEqual(uint32_t Other, 
+                      const FeatureBitset& FeatureBits) const {
+      if (FeatureBitSet.any() && 
+          (FeatureBitSet & FeatureBits).none())
         return false;
       return Value == Other;
     }
@@ -300,9 +307,11 @@ struct AArch64NamedImmMapper {
     : Mappings(&Mappings[0]), NumMappings(N), TooBigImm(TooBigImm) {}
 
   // Maps value to string, depending on availability for FeatureBits given
-  StringRef toString(uint32_t Value, uint64_t FeatureBits, bool &Valid) const;
+  StringRef toString(uint32_t Value, const FeatureBitset& FeatureBits,
+                     bool &Valid) const;
   // Maps string to value, depending on availability for FeatureBits given
-  uint32_t fromString(StringRef Name, uint64_t FeatureBits, bool &Valid) const;
+  uint32_t fromString(StringRef Name, const FeatureBitset& FeatureBits, 
+                     bool &Valid) const;
 
   /// Many of the instructions allow an alternative assembly form consisting of
   /// a simple immediate. Currently the only valid forms are ranges [0, N) where
@@ -1195,8 +1204,9 @@ namespace AArch64SysReg {
     size_t NumInstMappings;
 
     SysRegMapper() { }
-    uint32_t fromString(StringRef Name, uint64_t FeatureBits, bool &Valid) const;
-    std::string toString(uint32_t Bits, uint64_t FeatureBits) const;
+    uint32_t fromString(StringRef Name, const FeatureBitset& FeatureBits,
+                        bool &Valid) const;
+    std::string toString(uint32_t Bits, const FeatureBitset& FeatureBits) const;
   };
 
   struct MSRMapper : SysRegMapper {

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -415,7 +415,7 @@ bool ARMAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
 }
 
 static bool isThumb(const MCSubtargetInfo& STI) {
-  return (STI.getFeatureBits() & ARM::ModeThumb) != 0;
+  return STI.getFeatureBits()[ARM::ModeThumb];
 }
 
 void ARMAsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,

diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -4538,7 +4538,7 @@ breakPartialRegDependency(MachineBasicBlock::iterator MI,
 }
 
 bool ARMBaseInstrInfo::hasNOP() const {
-  return (Subtarget.getFeatureBits() & ARM::HasV6KOps) != 0;
+  return Subtarget.getFeatureBits()[ARM::HasV6KOps];
 }
 
 bool ARMBaseInstrInfo::isSwiftFastImmShift(const MachineInstr *MI) const {

diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -265,8 +265,8 @@ void ARMSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
   }
 
   // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
-  uint64_t Bits = getFeatureBits();
-  if ((Bits & ARM::ProcA5 || Bits & ARM::ProcA8) && // Where this matters
+  const FeatureBitset &Bits = getFeatureBits();
+  if ((Bits[ARM::ProcA5] || Bits[ARM::ProcA8]) && // Where this matters
       (Options.UnsafeFPMath || isTargetDarwin()))
     UseNEONForSinglePrecisionFP = true;
 }

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -243,48 +243,48 @@ class ARMAsmParser : public MCTargetAsmParser {
 
   bool isThumb() const {
     // FIXME: Can tablegen auto-generate this?
-    return (STI.getFeatureBits() & ARM::ModeThumb) != 0;
+    return STI.getFeatureBits()[ARM::ModeThumb];
   }
   bool isThumbOne() const {
-    return isThumb() && (STI.getFeatureBits() & ARM::FeatureThumb2) == 0;
+    return isThumb() && !STI.getFeatureBits()[ARM::FeatureThumb2];
   }
   bool isThumbTwo() const {
-    return isThumb() && (STI.getFeatureBits() & ARM::FeatureThumb2);
+    return isThumb() && STI.getFeatureBits()[ARM::FeatureThumb2];
   }
   bool hasThumb() const {
-    return STI.getFeatureBits() & ARM::HasV4TOps;
+    return STI.getFeatureBits()[ARM::HasV4TOps];
   }
   bool hasV6Ops() const {
-    return STI.getFeatureBits() & ARM::HasV6Ops;
+    return STI.getFeatureBits()[ARM::HasV6Ops];
   }
   bool hasV6MOps() const {
-    return STI.getFeatureBits() & ARM::HasV6MOps;
+    return STI.getFeatureBits()[ARM::HasV6MOps];
   }
   bool hasV7Ops() const {
-    return STI.getFeatureBits() & ARM::HasV7Ops;
+    return STI.getFeatureBits()[ARM::HasV7Ops];
   }
   bool hasV8Ops() const {
-    return STI.getFeatureBits() & ARM::HasV8Ops;
+    return STI.getFeatureBits()[ARM::HasV8Ops];
   }
   bool hasARM() const {
-    return !(STI.getFeatureBits() & ARM::FeatureNoARM);
+    return !STI.getFeatureBits()[ARM::FeatureNoARM];
   }
   bool hasThumb2DSP() const {
-    return STI.getFeatureBits() & ARM::FeatureDSPThumb2;
+    return STI.getFeatureBits()[ARM::FeatureDSPThumb2];
   }
   bool hasD16() const {
-    return STI.getFeatureBits() & ARM::FeatureD16;
+    return STI.getFeatureBits()[ARM::FeatureD16];
   }
   bool hasV8_1aOps() const {
-    return STI.getFeatureBits() & ARM::HasV8_1aOps;
+    return STI.getFeatureBits()[ARM::HasV8_1aOps];
   }
 
   void SwitchMode() {
     uint64_t FB = ComputeAvailableFeatures(STI.ToggleFeature(ARM::ModeThumb));
     setAvailableFeatures(FB);
   }
   bool isMClass() const {
-    return STI.getFeatureBits() & ARM::FeatureMClass;
+    return STI.getFeatureBits()[ARM::FeatureMClass];
   }
 
   /// @name Auto-generated Match Functions
@@ -9187,52 +9187,53 @@ bool ARMAsmParser::parseDirectiveCPU(SMLoc L) {
 // tools/clang/lib/Driver/Tools.cpp
 static const struct {
   const unsigned ID;
-  const uint64_t Enabled;
-  const uint64_t Disabled;
+  const FeatureBitset Enabled;
+  const FeatureBitset Disabled;
 } FPUs[] = {
-    {/* ID */ ARM::FK_VFP,
-     /* Enabled */ ARM::FeatureVFP2,
-     /* Disabled */ ARM::FeatureNEON},
-    {/* ID */ ARM::FK_VFPV2,
-     /* Enabled */ ARM::FeatureVFP2,
-     /* Disabled */ ARM::FeatureNEON},
-    {/* ID */ ARM::FK_VFPV3,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3,
-     /* Disabled */ ARM::FeatureNEON | ARM::FeatureD16},
-    {/* ID */ ARM::FK_VFPV3_D16,
-     /* Enable */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureD16,
-     /* Disabled */ ARM::FeatureNEON},
-    {/* ID */ ARM::FK_VFPV4,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4,
-     /* Disabled */ ARM::FeatureNEON | ARM::FeatureD16},
-    {/* ID */ ARM::FK_VFPV4_D16,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureD16,
-     /* Disabled */ ARM::FeatureNEON},
-    {/* ID */ ARM::FK_FPV5_D16,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureFPARMv8 | ARM::FeatureD16,
-     /* Disabled */ ARM::FeatureNEON | ARM::FeatureCrypto},
-    {/* ID */ ARM::FK_FP_ARMV8,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureFPARMv8,
-     /* Disabled */ ARM::FeatureNEON | ARM::FeatureCrypto | ARM::FeatureD16},
-    {/* ID */ ARM::FK_NEON,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureNEON,
-     /* Disabled */ ARM::FeatureD16},
-    {/* ID */ ARM::FK_NEON_VFPV4,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureNEON,
-     /* Disabled */ ARM::FeatureD16},
-    {/* ID */ ARM::FK_NEON_FP_ARMV8,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureFPARMv8 | ARM::FeatureNEON,
-     /* Disabled */ ARM::FeatureCrypto | ARM::FeatureD16},
+    {/* ID */ ARM::FK_VFP, 
+     /* Enabled */ {ARM::FeatureVFP2}, 
+     /* Disabled */ {ARM::FeatureNEON}},
+    {/* ID */ ARM::FK_VFPV2, 
+     /* Enabled */ {ARM::FeatureVFP2}, 
+     /* Disabled */ {ARM::FeatureNEON}},
+    {/* ID */ ARM::FK_VFPV3, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3},  
+     /* Disabled */ {ARM::FeatureNEON, ARM::FeatureD16}},
+    {/* ID */ ARM::FK_VFPV3_D16, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureD16},
+     /* Disabled */ {ARM::FeatureNEON}},
+    {/* ID */ ARM::FK_VFPV4, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4},
+     /* Disabled */ {ARM::FeatureNEON, ARM::FeatureD16}},
+    {/* ID */ ARM::FK_VFPV4_D16, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureD16},
+     /* Disabled */ {ARM::FeatureNEON}},
+    {/* ID */ ARM::FK_FPV5_D16, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureFPARMv8, ARM::FeatureD16},
+     /* Disabled */ {ARM::FeatureNEON, ARM::FeatureCrypto}},
+    {/* ID */ ARM::FK_FP_ARMV8, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureFPARMv8},
+     /* Disabled */ {ARM::FeatureNEON, ARM::FeatureCrypto, ARM::FeatureD16}},
+    {/* ID */ ARM::FK_NEON, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureNEON}, 
+     /* Disabled */ {ARM::FeatureD16}},
+    {/* ID */ ARM::FK_NEON_VFPV4, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureNEON}, 
+     /* Disabled */ {ARM::FeatureD16}},
+    {/* ID */ ARM::FK_NEON_FP_ARMV8, 
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureFPARMv8, ARM::FeatureNEON},
+     /* Disabled */ {ARM::FeatureCrypto, ARM::FeatureD16}},
     {/* ID */ ARM::FK_CRYPTO_NEON_FP_ARMV8,
-     /* Enabled */ ARM::FeatureVFP2 | ARM::FeatureVFP3 | ARM::FeatureVFP4 |
-         ARM::FeatureFPARMv8 | ARM::FeatureNEON | ARM::FeatureCrypto,
-     /* Disabled */ ARM::FeatureD16},
-    {ARM::FK_SOFTVFP, 0, 0},
+     /* Enabled */ {ARM::FeatureVFP2, ARM::FeatureVFP3, ARM::FeatureVFP4,
+                    ARM::FeatureFPARMv8, ARM::FeatureNEON, 
+                    ARM::FeatureCrypto},
+     /* Disabled */ {ARM::FeatureD16}},
+    {ARM::FK_SOFTVFP, {}, {}},
 };
 
 /// parseDirectiveFPU
@@ -9254,8 +9255,8 @@ bool ARMAsmParser::parseDirectiveFPU(SMLoc L) {
 
     // Need to toggle features that should be on but are off and that
     // should off but are on.
-    uint64_t Toggle = (Entry.Enabled & ~STI.getFeatureBits()) |
-                      (Entry.Disabled & STI.getFeatureBits());
+    FeatureBitset Toggle = (Entry.Enabled & ~STI.getFeatureBits()) |
+                           (Entry.Disabled & STI.getFeatureBits());
     setAvailableFeatures(ComputeAvailableFeatures(STI.ToggleFeature(Toggle)));
     break;
   }
@@ -9984,30 +9985,30 @@ extern "C" void LLVMInitializeARMAsmParser() {
 static const struct {
   const char *Name;
   const unsigned ArchCheck;
-  const uint64_t Features;
+  const FeatureBitset Features;
 } Extensions[] = {
-  { "crc", Feature_HasV8, ARM::FeatureCRC },
+  { "crc", Feature_HasV8, {ARM::FeatureCRC} },
   { "crypto",  Feature_HasV8,
-    ARM::FeatureCrypto | ARM::FeatureNEON | ARM::FeatureFPARMv8 },
-  { "fp", Feature_HasV8, ARM::FeatureFPARMv8 },
+    {ARM::FeatureCrypto, ARM::FeatureNEON, ARM::FeatureFPARMv8} },
+  { "fp", Feature_HasV8, {ARM::FeatureFPARMv8} },
   { "idiv", Feature_HasV7 | Feature_IsNotMClass,
-    ARM::FeatureHWDiv | ARM::FeatureHWDivARM },
+    {ARM::FeatureHWDiv, ARM::FeatureHWDivARM} },
   // FIXME: iWMMXT not supported
-  { "iwmmxt", Feature_None, 0 },
+  { "iwmmxt", Feature_None, {} },
   // FIXME: iWMMXT2 not supported
-  { "iwmmxt2", Feature_None, 0 },
+  { "iwmmxt2", Feature_None, {} },
   // FIXME: Maverick not supported
-  { "maverick", Feature_None, 0 },
-  { "mp", Feature_HasV7 | Feature_IsNotMClass, ARM::FeatureMP },
+  { "maverick", Feature_None, {} },
+  { "mp", Feature_HasV7 | Feature_IsNotMClass, {ARM::FeatureMP} },
   // FIXME: ARMv6-m OS Extensions feature not checked
-  { "os", Feature_None, 0 },
+  { "os", Feature_None, {} },
   // FIXME: Also available in ARMv6-K
-  { "sec", Feature_HasV7, ARM::FeatureTrustZone },
-  { "simd", Feature_HasV8, ARM::FeatureNEON | ARM::FeatureFPARMv8 },
+  { "sec", Feature_HasV7, {ARM::FeatureTrustZone} },
+  { "simd", Feature_HasV8, {ARM::FeatureNEON, ARM::FeatureFPARMv8} },
   // FIXME: Only available in A-class, isel not predicated
-  { "virt", Feature_HasV7, ARM::FeatureVirtualization },
+  { "virt", Feature_HasV7, {ARM::FeatureVirtualization} },
   // FIXME: xscale not supported
-  { "xscale", Feature_None, 0 },
+  { "xscale", Feature_None, {} },
 };
 
 /// parseDirectiveArchExtension
@@ -10035,7 +10036,7 @@ bool ARMAsmParser::parseDirectiveArchExtension(SMLoc L) {
     if (Extension.Name != Name)
       continue;
 
-    if (!Extension.Features)
+    if (Extension.Features.none())
       report_fatal_error("unsupported architectural extension: " + Name);
 
     if ((getAvailableFeatures() & Extension.ArchCheck) != Extension.ArchCheck) {
@@ -10044,9 +10045,10 @@ bool ARMAsmParser::parseDirectiveArchExtension(SMLoc L) {
       return false;
     }
 
-    uint64_t ToggleFeatures = EnableFeature
-                                  ? (~STI.getFeatureBits() & Extension.Features)
-                                  : ( STI.getFeatureBits() & Extension.Features);
+    FeatureBitset ToggleFeatures = EnableFeature
+      ? (~STI.getFeatureBits() & Extension.Features)
+      : ( STI.getFeatureBits() & Extension.Features);
+
     uint64_t Features =
         ComputeAvailableFeatures(STI.ToggleFeature(ToggleFeatures));
     setAvailableFeatures(Features);

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -435,7 +435,7 @@ DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                                              raw_ostream &CS) const {
   CommentStream = &CS;
 
-  assert(!(STI.getFeatureBits() & ARM::ModeThumb) &&
+  assert(!STI.getFeatureBits()[ARM::ModeThumb] &&
          "Asked to disassemble an ARM instruction but Subtarget is in Thumb "
          "mode!");
 
@@ -700,7 +700,7 @@ DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                                                raw_ostream &CS) const {
   CommentStream = &CS;
 
-  assert((STI.getFeatureBits() & ARM::ModeThumb) &&
+  assert(STI.getFeatureBits()[ARM::ModeThumb] &&
          "Asked to disassemble in Thumb mode but Subtarget is in ARM mode!");
 
   // We want to read exactly 2 bytes of data.
@@ -1026,9 +1026,10 @@ static const uint16_t DPRDecoderTable[] = {
 
 static DecodeStatus DecodeDPRRegisterClass(MCInst &Inst, unsigned RegNo,
                                    uint64_t Address, const void *Decoder) {
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  bool hasD16 = featureBits & ARM::FeatureD16;
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  bool hasD16 = featureBits[ARM::FeatureD16];
 
   if (RegNo > 31 || (hasD16 && RegNo > 15))
     return MCDisassembler::Fail;
@@ -1373,9 +1374,9 @@ static DecodeStatus DecodeCopMemInstruction(MCInst &Inst, unsigned Insn,
       break;
   }
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  if ((featureBits & ARM::HasV8Ops) && (coproc != 14))
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+  if (featureBits[ARM::HasV8Ops] && (coproc != 14))
     return MCDisassembler::Fail;
 
   Inst.addOperand(MCOperand::createImm(coproc));
@@ -2151,9 +2152,10 @@ static DecodeStatus DecodeSETPANInstruction(MCInst &Inst, unsigned Insn,
   unsigned Imm = fieldFromInstruction(Insn, 9, 1);
 
   const MCDisassembler *Dis = static_cast<const MCDisassembler*>(Decoder);
-  uint64_t FeatureBits = Dis->getSubtargetInfo().getFeatureBits();
-  if ((FeatureBits & ARM::HasV8_1aOps) == 0 || 
-      (FeatureBits & ARM::HasV8Ops) == 0 )
+  const FeatureBitset &FeatureBits = Dis->getSubtargetInfo().getFeatureBits();
+
+  if (!FeatureBits[ARM::HasV8_1aOps] || 
+      !FeatureBits[ARM::HasV8Ops])
     return MCDisassembler::Fail;
 
   // Decoder can be called from DecodeTST, which does not check the full
@@ -3319,10 +3321,11 @@ static DecodeStatus DecodeT2LoadShift(MCInst &Inst, unsigned Insn,
   unsigned Rt = fieldFromInstruction(Insn, 12, 4);
   unsigned Rn = fieldFromInstruction(Insn, 16, 4);
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  bool hasMP = featureBits & ARM::FeatureMP;
-  bool hasV7Ops = featureBits & ARM::HasV7Ops;
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  bool hasMP = featureBits[ARM::FeatureMP];
+  bool hasV7Ops = featureBits[ARM::HasV7Ops];
 
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
@@ -3405,10 +3408,11 @@ static DecodeStatus DecodeT2LoadImm8(MCInst &Inst, unsigned Insn,
   imm |= (Rn << 9);
   unsigned add = fieldFromInstruction(Insn, 9, 1);
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  bool hasMP = featureBits & ARM::FeatureMP;
-  bool hasV7Ops = featureBits & ARM::HasV7Ops;
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  bool hasMP = featureBits[ARM::FeatureMP];
+  bool hasV7Ops = featureBits[ARM::HasV7Ops];
 
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
@@ -3485,10 +3489,11 @@ static DecodeStatus DecodeT2LoadImm12(MCInst &Inst, unsigned Insn,
   unsigned imm = fieldFromInstruction(Insn, 0, 12);
   imm |= (Rn << 13);
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  bool hasMP = (featureBits & ARM::FeatureMP);
-  bool hasV7Ops = (featureBits & ARM::HasV7Ops);
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  bool hasMP = featureBits[ARM::FeatureMP];
+  bool hasV7Ops = featureBits[ARM::HasV7Ops];
 
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
@@ -3602,9 +3607,10 @@ static DecodeStatus DecodeT2LoadLabel(MCInst &Inst, unsigned Insn,
   unsigned U = fieldFromInstruction(Insn, 23, 1);
   int imm = fieldFromInstruction(Insn, 0, 12);
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  bool hasV7Ops = (featureBits & ARM::HasV7Ops);
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  bool hasV7Ops = featureBits[ARM::HasV7Ops];
 
   if (Rt == 15) {
     switch (Inst.getOpcode()) {
@@ -3925,9 +3931,10 @@ static DecodeStatus DecodeCoprocessor(MCInst &Inst, unsigned Val,
   if (Val == 0xA || Val == 0xB)
     return MCDisassembler::Fail;
 
-  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  if ((featureBits & ARM::HasV8Ops) && !(Val == 14 || Val == 15))
+  const FeatureBitset &featureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  if (featureBits[ARM::HasV8Ops] && !(Val == 14 || Val == 15))
     return MCDisassembler::Fail;
 
   Inst.addOperand(MCOperand::createImm(Val));
@@ -4077,9 +4084,10 @@ static DecodeStatus DecodeInstSyncBarrierOption(MCInst &Inst, unsigned Val,
 static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Val,
                           uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
-  uint64_t FeatureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
-                                                          .getFeatureBits();
-  if (FeatureBits & ARM::FeatureMClass) {
+  const FeatureBitset &FeatureBits =
+    ((const MCDisassembler*)Decoder)->getSubtargetInfo().getFeatureBits();
+
+  if (FeatureBits[ARM::FeatureMClass]) {
     unsigned ValLow = Val & 0xff;
 
     // Validate the SYSm value first.
@@ -4099,7 +4107,7 @@ static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Val,
     case 17: // basepri
     case 18: // basepri_max
     case 19: // faultmask
-      if (!(FeatureBits & ARM::HasV7Ops))
+      if (!(FeatureBits[ARM::HasV7Ops]))
         // Values basepri, basepri_max and faultmask are only valid for v7m.
         return MCDisassembler::Fail;
       break;
@@ -4109,7 +4117,7 @@ static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Val,
 
     if (Inst.getOpcode() == ARM::t2MSR_M) {
       unsigned Mask = fieldFromInstruction(Val, 10, 2);
-      if (!(FeatureBits & ARM::HasV7Ops)) {
+      if (!(FeatureBits[ARM::HasV7Ops])) {
         // The ARMv6-M MSR bits {11-10} can be only 0b10, other values are
         // unpredictable.
         if (Mask != 2)
@@ -4123,7 +4131,7 @@ static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Val,
         // indicates the move for the GE{3:0} bits, the mask{0} bit can be set
         // only if the processor includes the DSP extension.
         if (Mask == 0 || (Mask != 2 && ValLow > 3) ||
-            (!(FeatureBits & ARM::FeatureDSPThumb2) && (Mask & 1)))
+            (!(FeatureBits[ARM::FeatureDSPThumb2]) && (Mask & 1)))
           S = MCDisassembler::SoftFail;
       }
     }

diff --git a/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp b/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
@@ -93,7 +93,7 @@ void ARMInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
       O << "\tsev";
       break;
     case 5:
-      if ((STI.getFeatureBits() & ARM::HasV8Ops)) {
+      if (STI.getFeatureBits()[ARM::HasV8Ops]) {
         O << "\tsevl";
         break;
       } // Fallthrough for non-v8
@@ -302,7 +302,7 @@ void ARMInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
   case ARM::t2SUBS_PC_LR: {
     if (MI->getNumOperands() == 3 && MI->getOperand(0).isImm() &&
         MI->getOperand(0).getImm() == 0 &&
-        (STI.getFeatureBits() & ARM::FeatureVirtualization)) {
+        STI.getFeatureBits()[ARM::FeatureVirtualization]) {
       O << "\teret";
       printPredicateOperand(MI, 1, STI, O);
       printAnnotation(O, Annot);
@@ -695,7 +695,7 @@ void ARMInstPrinter::printMemBOption(const MCInst *MI, unsigned OpNum,
                                      const MCSubtargetInfo &STI,
                                      raw_ostream &O) {
   unsigned val = MI->getOperand(OpNum).getImm();
-  O << ARM_MB::MemBOptToString(val, (STI.getFeatureBits() & ARM::HasV8Ops));
+  O << ARM_MB::MemBOptToString(val, STI.getFeatureBits()[ARM::HasV8Ops]);
 }
 
 void ARMInstPrinter::printInstSyncBOption(const MCInst *MI, unsigned OpNum,
@@ -795,14 +795,14 @@ void ARMInstPrinter::printMSRMaskOperand(const MCInst *MI, unsigned OpNum,
   const MCOperand &Op = MI->getOperand(OpNum);
   unsigned SpecRegRBit = Op.getImm() >> 4;
   unsigned Mask = Op.getImm() & 0xf;
-  uint64_t FeatureBits = STI.getFeatureBits();
+  const FeatureBitset &FeatureBits = STI.getFeatureBits();
 
-  if (FeatureBits & ARM::FeatureMClass) {
+  if (FeatureBits[ARM::FeatureMClass]) {
     unsigned SYSm = Op.getImm();
     unsigned Opcode = MI->getOpcode();
 
     // For writes, handle extended mask bits if the DSP extension is present.
-    if (Opcode == ARM::t2MSR_M && (FeatureBits & ARM::FeatureDSPThumb2)) {
+    if (Opcode == ARM::t2MSR_M && FeatureBits[ARM::FeatureDSPThumb2]) {
       switch (SYSm) {
       case 0x400:
         O << "apsr_g";
@@ -834,7 +834,7 @@ void ARMInstPrinter::printMSRMaskOperand(const MCInst *MI, unsigned OpNum,
     // Handle the basic 8-bit mask.
     SYSm &= 0xff;
 
-    if (Opcode == ARM::t2MSR_M && (FeatureBits & ARM::HasV7Ops)) {
+    if (Opcode == ARM::t2MSR_M && FeatureBits [ARM::HasV7Ops]) {
       // ARMv7-M deprecates using MSR APSR without a _<bits> qualifier as an
       // alias for MSR APSR_nzcvq.
       switch (SYSm) {

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -154,7 +154,7 @@ void ARMAsmBackend::handleAssemblerFlag(MCAssemblerFlag Flag) {
 } // end anonymous namespace
 
 unsigned ARMAsmBackend::getRelaxedOpcode(unsigned Op) const {
-  bool HasThumb2 = STI->getFeatureBits() & ARM::FeatureThumb2;
+  bool HasThumb2 = STI->getFeatureBits()[ARM::FeatureThumb2];
 
   switch (Op) {
   default:

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
@@ -33,7 +33,7 @@ class ARMAsmBackend : public MCAsmBackend {
     return ARM::NumTargetFixupKinds;
   }
 
-  bool hasNOP() const { return (STI->getFeatureBits() & ARM::HasV6T2Ops) != 0; }
+  bool hasNOP() const { return STI->getFeatureBits()[ARM::HasV6T2Ops]; }
 
   const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
 

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -51,10 +51,10 @@ class ARMMCCodeEmitter : public MCCodeEmitter {
   ~ARMMCCodeEmitter() override {}
 
   bool isThumb(const MCSubtargetInfo &STI) const {
-    return (STI.getFeatureBits() & ARM::ModeThumb) != 0;
+    return STI.getFeatureBits()[ARM::ModeThumb];
   }
   bool isThumb2(const MCSubtargetInfo &STI) const {
-    return isThumb(STI) && (STI.getFeatureBits() & ARM::FeatureThumb2) != 0;
+    return isThumb(STI) && STI.getFeatureBits()[ARM::FeatureThumb2];
   }
   bool isTargetMachO(const MCSubtargetInfo &STI) const {
     Triple TT(STI.getTargetTriple());

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
@@ -33,7 +33,7 @@ using namespace llvm;
 
 static bool getMCRDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
                                   std::string &Info) {
-  if (STI.getFeatureBits() & llvm::ARM::HasV7Ops &&
+  if (STI.getFeatureBits()[llvm::ARM::HasV7Ops] &&
       (MI.getOperand(0).isImm() && MI.getOperand(0).getImm() == 15) &&
       (MI.getOperand(1).isImm() && MI.getOperand(1).getImm() == 0) &&
       // Checks for the deprecated CP15ISB encoding:
@@ -65,7 +65,7 @@ static bool getMCRDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
 
 static bool getITDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
                                  std::string &Info) {
-  if (STI.getFeatureBits() & llvm::ARM::HasV8Ops && MI.getOperand(1).isImm() &&
+  if (STI.getFeatureBits()[llvm::ARM::HasV8Ops] && MI.getOperand(1).isImm() &&
       MI.getOperand(1).getImm() != 8) {
     Info = "applying IT instruction to more than one subsequent instruction is "
            "deprecated";
@@ -77,7 +77,7 @@ static bool getITDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
 
 static bool getARMStoreDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
                                        std::string &Info) {
-  assert((~STI.getFeatureBits() & llvm::ARM::ModeThumb) &&
+  assert(!STI.getFeatureBits()[llvm::ARM::ModeThumb] &&
          "cannot predicate thumb instructions");
 
   assert(MI.getNumOperands() >= 4 && "expected >= 4 arguments");
@@ -94,7 +94,7 @@ static bool getARMStoreDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
 
 static bool getARMLoadDeprecationInfo(MCInst &MI, MCSubtargetInfo &STI,
                                       std::string &Info) {
-  assert((~STI.getFeatureBits() & llvm::ARM::ModeThumb) &&
+  assert(!STI.getFeatureBits()[llvm::ARM::ModeThumb] &&
          "cannot predicate thumb instructions");
 
   assert(MI.getNumOperands() >= 4 && "expected >= 4 arguments");

diff --git a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -78,15 +78,7 @@ class MipsAssemblerOptions {
   // The full table can be found in MipsGenSubtargetInfo.inc (MipsFeatureKV[]).
   // The reason we need this mask is explained in the selectArch function.
   // FIXME: Ideally we would like TableGen to generate this information.
-  static const uint64_t AllArchRelatedMask =
-      Mips::FeatureMips1 | Mips::FeatureMips2 | Mips::FeatureMips3 |
-      Mips::FeatureMips3_32 | Mips::FeatureMips3_32r2 | Mips::FeatureMips4 |
-      Mips::FeatureMips4_32 | Mips::FeatureMips4_32r2 | Mips::FeatureMips5 |
-      Mips::FeatureMips5_32r2 | Mips::FeatureMips32 | Mips::FeatureMips32r2 |
-      Mips::FeatureMips32r3 | Mips::FeatureMips32r5 | Mips::FeatureMips32r6 |
-      Mips::FeatureMips64 | Mips::FeatureMips64r2 | Mips::FeatureMips64r3 |
-      Mips::FeatureMips64r5 | Mips::FeatureMips64r6 | Mips::FeatureCnMips |
-      Mips::FeatureFP64Bit | Mips::FeatureGP64Bit | Mips::FeatureNaN2008;
+  static const FeatureBitset AllArchRelatedMask;
 
 private:
   unsigned ATReg;
@@ -96,6 +88,17 @@ class MipsAssemblerOptions {
 };
 }
 
+const FeatureBitset MipsAssemblerOptions::AllArchRelatedMask = {
+    Mips::FeatureMips1, Mips::FeatureMips2, Mips::FeatureMips3,
+    Mips::FeatureMips3_32, Mips::FeatureMips3_32r2, Mips::FeatureMips4,
+    Mips::FeatureMips4_32, Mips::FeatureMips4_32r2, Mips::FeatureMips5,
+    Mips::FeatureMips5_32r2, Mips::FeatureMips32, Mips::FeatureMips32r2,
+    Mips::FeatureMips32r3, Mips::FeatureMips32r5, Mips::FeatureMips32r6,
+    Mips::FeatureMips64, Mips::FeatureMips64r2, Mips::FeatureMips64r3,
+    Mips::FeatureMips64r5, Mips::FeatureMips64r6, Mips::FeatureCnMips,
+    Mips::FeatureFP64Bit, Mips::FeatureGP64Bit, Mips::FeatureNaN2008
+};
+
 namespace {
 class MipsAsmParser : public MCTargetAsmParser {
   MipsTargetStreamer &getTargetStreamer() {
@@ -317,7 +320,7 @@ class MipsAsmParser : public MCTargetAsmParser {
   // FeatureMipsGP64 | FeatureMips1)
   // Clearing Mips3 is equivalent to clear (FeatureMips3 | FeatureMips4).
   void selectArch(StringRef ArchFeature) {
-    uint64_t FeatureBits = STI.getFeatureBits();
+    FeatureBitset FeatureBits = STI.getFeatureBits();
     FeatureBits &= ~MipsAssemblerOptions::AllArchRelatedMask;
     STI.setFeatureBits(FeatureBits);
     setAvailableFeatures(
@@ -326,15 +329,15 @@ class MipsAsmParser : public MCTargetAsmParser {
   }
 
   void setFeatureBits(uint64_t Feature, StringRef FeatureString) {
-    if (!(STI.getFeatureBits() & Feature)) {
+    if (!(STI.getFeatureBits()[Feature])) {
       setAvailableFeatures(
           ComputeAvailableFeatures(STI.ToggleFeature(FeatureString)));
     }
     AssemblerOptions.back()->setFeatures(getAvailableFeatures());
   }
 
   void clearFeatureBits(uint64_t Feature, StringRef FeatureString) {
-    if (STI.getFeatureBits() & Feature) {
+    if (STI.getFeatureBits()[Feature]) {
       setAvailableFeatures(
           ComputeAvailableFeatures(STI.ToggleFeature(FeatureString)));
     }
@@ -381,69 +384,70 @@ class MipsAsmParser : public MCTargetAsmParser {
   /// True if all of $fcc0 - $fcc7 exist for the current ISA.
   bool hasEightFccRegisters() const { return hasMips4() || hasMips32(); }
 
-  bool isGP64bit() const { return STI.getFeatureBits() & Mips::FeatureGP64Bit; }
-  bool isFP64bit() const { return STI.getFeatureBits() & Mips::FeatureFP64Bit; }
+  bool isGP64bit() const { return STI.getFeatureBits()[Mips::FeatureGP64Bit]; }
+  bool isFP64bit() const { return STI.getFeatureBits()[Mips::FeatureFP64Bit]; }
   const MipsABIInfo &getABI() const { return ABI; }
   bool isABI_N32() const { return ABI.IsN32(); }
   bool isABI_N64() const { return ABI.IsN64(); }
   bool isABI_O32() const { return ABI.IsO32(); }
-  bool isABI_FPXX() const { return STI.getFeatureBits() & Mips::FeatureFPXX; }
+  bool isABI_FPXX() const { return STI.getFeatureBits()[Mips::FeatureFPXX]; }
 
   bool useOddSPReg() const {
-    return !(STI.getFeatureBits() & Mips::FeatureNoOddSPReg);
+    return !(STI.getFeatureBits()[Mips::FeatureNoOddSPReg]);
   }
 
   bool inMicroMipsMode() const {
-    return STI.getFeatureBits() & Mips::FeatureMicroMips;
+    return STI.getFeatureBits()[Mips::FeatureMicroMips];
   }
-  bool hasMips1() const { return STI.getFeatureBits() & Mips::FeatureMips1; }
-  bool hasMips2() const { return STI.getFeatureBits() & Mips::FeatureMips2; }
-  bool hasMips3() const { return STI.getFeatureBits() & Mips::FeatureMips3; }
-  bool hasMips4() const { return STI.getFeatureBits() & Mips::FeatureMips4; }
-  bool hasMips5() const { return STI.getFeatureBits() & Mips::FeatureMips5; }
+  bool hasMips1() const { return STI.getFeatureBits()[Mips::FeatureMips1]; }
+  bool hasMips2() const { return STI.getFeatureBits()[Mips::FeatureMips2]; }
+  bool hasMips3() const { return STI.getFeatureBits()[Mips::FeatureMips3]; }
+  bool hasMips4() const { return STI.getFeatureBits()[Mips::FeatureMips4]; }
+  bool hasMips5() const { return STI.getFeatureBits()[Mips::FeatureMips5]; }
   bool hasMips32() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips32);
+    return STI.getFeatureBits()[Mips::FeatureMips32];
   }
   bool hasMips64() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips64);
+    return STI.getFeatureBits()[Mips::FeatureMips64];
   }
   bool hasMips32r2() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips32r2);
+    return STI.getFeatureBits()[Mips::FeatureMips32r2];
   }
   bool hasMips64r2() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips64r2);
+    return STI.getFeatureBits()[Mips::FeatureMips64r2];
   }
   bool hasMips32r3() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips32r3);
+    return (STI.getFeatureBits()[Mips::FeatureMips32r3]);
   }
   bool hasMips64r3() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips64r3);
+    return (STI.getFeatureBits()[Mips::FeatureMips64r3]);
   }
   bool hasMips32r5() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips32r5);
+    return (STI.getFeatureBits()[Mips::FeatureMips32r5]);
   }
   bool hasMips64r5() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips64r5);
+    return (STI.getFeatureBits()[Mips::FeatureMips64r5]);
   }
   bool hasMips32r6() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips32r6);
+    return STI.getFeatureBits()[Mips::FeatureMips32r6];
   }
   bool hasMips64r6() const {
-    return (STI.getFeatureBits() & Mips::FeatureMips64r6);
+    return STI.getFeatureBits()[Mips::FeatureMips64r6];
   }
+
+  bool hasDSP() const { return STI.getFeatureBits()[Mips::FeatureDSP]; }
+  bool hasDSPR2() const { return STI.getFeatureBits()[Mips::FeatureDSPR2]; }
+  bool hasMSA() const { return STI.getFeatureBits()[Mips::FeatureMSA]; }
   bool hasCnMips() const {
-    return (STI.getFeatureBits() & Mips::FeatureCnMips);
+    return (STI.getFeatureBits()[Mips::FeatureCnMips]);
   }
-  bool hasDSP() const { return (STI.getFeatureBits() & Mips::FeatureDSP); }
-  bool hasDSPR2() const { return (STI.getFeatureBits() & Mips::FeatureDSPR2); }
-  bool hasMSA() const { return (STI.getFeatureBits() & Mips::FeatureMSA); }
 
   bool inMips16Mode() const {
-    return STI.getFeatureBits() & Mips::FeatureMips16;
+    return STI.getFeatureBits()[Mips::FeatureMips16];
   }
 
   bool useSoftFloat() const {
-    return (STI.getFeatureBits() & Mips::FeatureSoftFloat);
+    return STI.getFeatureBits()[Mips::FeatureSoftFloat];
   }
 
   /// Warn if RegIndex is the same as the current AT.

diff --git a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -36,16 +36,16 @@ class MipsDisassembler : public MCDisassembler {
 public:
   MipsDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx, bool IsBigEndian)
       : MCDisassembler(STI, Ctx),
-        IsMicroMips(STI.getFeatureBits() & Mips::FeatureMicroMips),
+        IsMicroMips(STI.getFeatureBits()[Mips::FeatureMicroMips]),
         IsBigEndian(IsBigEndian) {}
 
-  bool hasMips3() const { return STI.getFeatureBits() & Mips::FeatureMips3; }
-  bool hasMips32() const { return STI.getFeatureBits() & Mips::FeatureMips32; }
+  bool hasMips3() const { return STI.getFeatureBits()[Mips::FeatureMips3]; }
+  bool hasMips32() const { return STI.getFeatureBits()[Mips::FeatureMips32]; }
   bool hasMips32r6() const {
-    return STI.getFeatureBits() & Mips::FeatureMips32r6;
+    return STI.getFeatureBits()[Mips::FeatureMips32r6];
   }
 
-  bool isGP64() const { return STI.getFeatureBits() & Mips::FeatureGP64Bit; }
+  bool isGP64() const { return STI.getFeatureBits()[Mips::FeatureGP64Bit]; }
 
   bool hasCOP3() const {
     // Only present in MIPS-I and MIPS-II

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp
@@ -113,11 +113,11 @@ static void LowerDextDins(MCInst& InstIn) {
 }
 
 bool MipsMCCodeEmitter::isMicroMips(const MCSubtargetInfo &STI) const {
-  return STI.getFeatureBits() & Mips::FeatureMicroMips;
+  return STI.getFeatureBits()[Mips::FeatureMicroMips];
 }
 
 bool MipsMCCodeEmitter::isMips32r6(const MCSubtargetInfo &STI) const {
-  return STI.getFeatureBits() & Mips::FeatureMips32r6;
+  return STI.getFeatureBits()[Mips::FeatureMips32r6];
 }
 
 void MipsMCCodeEmitter::EmitByte(unsigned char C, raw_ostream &OS) const {

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -386,7 +386,7 @@ MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
   MCAssembler &MCA = getStreamer().getAssembler();
   Pic = MCA.getContext().getObjectFileInfo()->getRelocM() == Reloc::PIC_;
 
-  uint64_t Features = STI.getFeatureBits();
+  const FeatureBitset &Features = STI.getFeatureBits();
 
   // Set the header flags that we can in the constructor.
   // FIXME: This is a fairly terrible hack. We set the rest
@@ -402,35 +402,35 @@ MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
   unsigned EFlags = MCA.getELFHeaderEFlags();
 
   // Architecture
-  if (Features & Mips::FeatureMips64r6)
+  if (Features[Mips::FeatureMips64r6])
     EFlags |= ELF::EF_MIPS_ARCH_64R6;
-  else if (Features & Mips::FeatureMips64r2 ||
-           Features & Mips::FeatureMips64r3 ||
-           Features & Mips::FeatureMips64r5)
+  else if (Features[Mips::FeatureMips64r2] ||
+           Features[Mips::FeatureMips64r3] ||
+           Features[Mips::FeatureMips64r5])
     EFlags |= ELF::EF_MIPS_ARCH_64R2;
-  else if (Features & Mips::FeatureMips64)
+  else if (Features[Mips::FeatureMips64])
     EFlags |= ELF::EF_MIPS_ARCH_64;
-  else if (Features & Mips::FeatureMips5)
+  else if (Features[Mips::FeatureMips5])
     EFlags |= ELF::EF_MIPS_ARCH_5;
-  else if (Features & Mips::FeatureMips4)
+  else if (Features[Mips::FeatureMips4])
     EFlags |= ELF::EF_MIPS_ARCH_4;
-  else if (Features & Mips::FeatureMips3)
+  else if (Features[Mips::FeatureMips3])
     EFlags |= ELF::EF_MIPS_ARCH_3;
-  else if (Features & Mips::FeatureMips32r6)
+  else if (Features[Mips::FeatureMips32r6])
     EFlags |= ELF::EF_MIPS_ARCH_32R6;
-  else if (Features & Mips::FeatureMips32r2 ||
-           Features & Mips::FeatureMips32r3 ||
-           Features & Mips::FeatureMips32r5)
+  else if (Features[Mips::FeatureMips32r2] ||
+           Features[Mips::FeatureMips32r3] ||
+           Features[Mips::FeatureMips32r5])
     EFlags |= ELF::EF_MIPS_ARCH_32R2;
-  else if (Features & Mips::FeatureMips32)
+  else if (Features[Mips::FeatureMips32])
     EFlags |= ELF::EF_MIPS_ARCH_32;
-  else if (Features & Mips::FeatureMips2)
+  else if (Features[Mips::FeatureMips2])
     EFlags |= ELF::EF_MIPS_ARCH_2;
   else
     EFlags |= ELF::EF_MIPS_ARCH_1;
 
   // Other options.
-  if (Features & Mips::FeatureNaN2008)
+  if (Features[Mips::FeatureNaN2008])
     EFlags |= ELF::EF_MIPS_NAN2008;
 
   // -mabicalls and -mplt are not implemented but we should act as if they were
@@ -470,7 +470,7 @@ void MipsTargetELFStreamer::finish() {
   DataSection.setAlignment(std::max(16u, DataSection.getAlignment()));
   BSSSection.setAlignment(std::max(16u, BSSSection.getAlignment()));
 
-  uint64_t Features = STI.getFeatureBits();
+  const FeatureBitset &Features = STI.getFeatureBits();
 
   // Update e_header flags. See the FIXME and comment above in
   // the constructor for a full rundown on this.
@@ -483,10 +483,10 @@ void MipsTargetELFStreamer::finish() {
   else if (getABI().IsN32())
     EFlags |= ELF::EF_MIPS_ABI2;
 
-  if (Features & Mips::FeatureGP64Bit) {
+  if (Features[Mips::FeatureGP64Bit]) {
     if (getABI().IsO32())
       EFlags |= ELF::EF_MIPS_32BITMODE; /* Compatibility Mode */
-  } else if (Features & Mips::FeatureMips64r2 || Features & Mips::FeatureMips64)
+  } else if (Features[Mips::FeatureMips64r2] || Features[Mips::FeatureMips64])
     EFlags |= ELF::EF_MIPS_32BITMODE;
 
   // If we've set the cpic eflag and we're n64, go ahead and set the pic

diff --git a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
@@ -1682,7 +1682,7 @@ bool PPCAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
   //  where th can be omitted when it is 0. dcbtst is the same. We take the
   //  server form to be the default, so swap the operands if we're parsing for
   //  an embedded core (they'll be swapped again upon printing).
-  if ((STI.getFeatureBits() & PPC::FeatureBookE) != 0 &&
+  if (STI.getFeatureBits()[PPC::FeatureBookE] &&
       Operands.size() == 4 &&
       (Name == "dcbt" || Name == "dcbtst")) {
     std::swap(Operands[1], Operands[3]);

diff --git a/llvm/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp b/llvm/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp
@@ -387,7 +387,7 @@ DecodeStatus PPCDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
   uint32_t Inst =
       (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 8) | (Bytes[3] << 0);
 
-  if ((STI.getFeatureBits() & PPC::FeatureQPX) != 0) {
+  if (STI.getFeatureBits()[PPC::FeatureQPX]) {
     DecodeStatus result =
       decodeInstruction(DecoderTableQPX32, MI, Inst, Address, this, STI);
     if (result != MCDisassembler::Fail)

diff --git a/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp b/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
@@ -121,7 +121,7 @@ void PPCInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
       O << "t";
     O << " ";
 
-    bool IsBookE = (STI.getFeatureBits() & PPC::FeatureBookE) != 0;
+    bool IsBookE = STI.getFeatureBits()[PPC::FeatureBookE];
     if (IsBookE && TH != 0 && TH != 16)
       O << (unsigned int) TH << ", ";
 

diff --git a/llvm/lib/Target/R600/AsmParser/AMDGPUAsmParser.cpp b/llvm/lib/Target/R600/AsmParser/AMDGPUAsmParser.cpp
@@ -321,7 +321,7 @@ class AMDGPUAsmParser : public MCTargetAsmParser {
       : MCTargetAsmParser(), STI(STI), MII(MII), Parser(_Parser),
         ForcedEncodingSize(0){
 
-    if (!STI.getFeatureBits()) {
+    if (STI.getFeatureBits().none()) {
       // Set default features.
       STI.ToggleFeature("SOUTHERN_ISLANDS");
     }

diff --git a/llvm/lib/Target/R600/MCTargetDesc/R600MCCodeEmitter.cpp b/llvm/lib/Target/R600/MCTargetDesc/R600MCCodeEmitter.cpp
@@ -99,7 +99,7 @@ void R600MCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
   } else if (IS_VTX(Desc)) {
     uint64_t InstWord01 = getBinaryCodeForInstr(MI, Fixups, STI);
     uint32_t InstWord2 = MI.getOperand(2).getImm(); // Offset
-    if (!(STI.getFeatureBits() & AMDGPU::FeatureCaymanISA)) {
+    if (!(STI.getFeatureBits()[AMDGPU::FeatureCaymanISA])) {
       InstWord2 |= 1 << 19; // Mega-Fetch bit
     }
 
@@ -132,7 +132,7 @@ void R600MCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
       Emit((uint32_t) 0, OS);
   } else {
     uint64_t Inst = getBinaryCodeForInstr(MI, Fixups, STI);
-    if ((STI.getFeatureBits() & AMDGPU::FeatureR600ALUInst) &&
+    if ((STI.getFeatureBits()[AMDGPU::FeatureR600ALUInst]) &&
        ((Desc.TSFlags & R600_InstFlag::OP1) ||
          Desc.TSFlags & R600_InstFlag::OP2)) {
       uint64_t ISAOpCode = Inst & (0x3FFULL << 39);

diff --git a/llvm/lib/Target/Sparc/InstPrinter/SparcInstPrinter.cpp b/llvm/lib/Target/Sparc/InstPrinter/SparcInstPrinter.cpp
@@ -35,7 +35,7 @@ namespace Sparc {
 #include "SparcGenAsmWriter.inc"
 
 bool SparcInstPrinter::isV9(const MCSubtargetInfo &STI) const {
-  return (STI.getFeatureBits() & Sparc::FeatureV9) != 0;
+  return (STI.getFeatureBits()[Sparc::FeatureV9]) != 0;
 }
 
 void SparcInstPrinter::printRegName(raw_ostream &OS, unsigned RegNo) const

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmInstrumentation.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmInstrumentation.cpp
@@ -261,13 +261,13 @@ class X86AddressSanitizer : public X86AsmInstrumentation {
                                               MCContext &Ctx, int64_t *Residue);
 
   bool is64BitMode() const {
-    return (STI.getFeatureBits() & X86::Mode64Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode64Bit];
   }
   bool is32BitMode() const {
-    return (STI.getFeatureBits() & X86::Mode32Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode32Bit];
   }
   bool is16BitMode() const {
-    return (STI.getFeatureBits() & X86::Mode16Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode16Bit];
   }
 
   unsigned getPointerWidth() {
@@ -1072,9 +1072,9 @@ CreateX86AsmInstrumentation(const MCTargetOptions &MCOptions,
   const bool hasCompilerRTSupport = T.isOSLinux();
   if (ClAsanInstrumentAssembly && hasCompilerRTSupport &&
       MCOptions.SanitizeAddress) {
-    if ((STI.getFeatureBits() & X86::Mode32Bit) != 0)
+    if (STI.getFeatureBits()[X86::Mode32Bit] != 0)
       return new X86AddressSanitizer32(STI);
-    if ((STI.getFeatureBits() & X86::Mode64Bit) != 0)
+    if (STI.getFeatureBits()[X86::Mode64Bit] != 0)
       return new X86AddressSanitizer64(STI);
   }
   return new X86AsmInstrumentation(STI);

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -729,23 +729,24 @@ class X86AsmParser : public MCTargetAsmParser {
 
   bool is64BitMode() const {
     // FIXME: Can tablegen auto-generate this?
-    return (STI.getFeatureBits() & X86::Mode64Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode64Bit];
   }
   bool is32BitMode() const {
     // FIXME: Can tablegen auto-generate this?
-    return (STI.getFeatureBits() & X86::Mode32Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode32Bit];
   }
   bool is16BitMode() const {
     // FIXME: Can tablegen auto-generate this?
-    return (STI.getFeatureBits() & X86::Mode16Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode16Bit];
   }
-  void SwitchMode(uint64_t mode) {
-    uint64_t oldMode = STI.getFeatureBits() &
-        (X86::Mode64Bit | X86::Mode32Bit | X86::Mode16Bit);
-    unsigned FB = ComputeAvailableFeatures(STI.ToggleFeature(oldMode | mode));
+  void SwitchMode(unsigned mode) {
+    FeatureBitset AllModes({X86::Mode64Bit, X86::Mode32Bit, X86::Mode16Bit});
+    FeatureBitset OldMode = STI.getFeatureBits() & AllModes;
+    unsigned FB = ComputeAvailableFeatures(
+      STI.ToggleFeature(OldMode.flip(mode)));
     setAvailableFeatures(FB);
-    assert(mode == (STI.getFeatureBits() &
-                    (X86::Mode64Bit | X86::Mode32Bit | X86::Mode16Bit)));
+
+    assert(FeatureBitset({mode}) == (STI.getFeatureBits() & AllModes));
   }
 
   unsigned getPointerWidth() {
@@ -1696,7 +1697,7 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseIntelOperand() {
   }
 
   // rounding mode token
-  if (STI.getFeatureBits() & X86::FeatureAVX512 &&
+  if (STI.getFeatureBits()[X86::FeatureAVX512] &&
       getLexer().is(AsmToken::LCurly))
     return ParseRoundingModeOp(Start, End);
 
@@ -1754,7 +1755,7 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseATTOperand() {
   }
   case AsmToken::LCurly:{
     SMLoc Start = Parser.getTok().getLoc(), End;
-    if (STI.getFeatureBits() & X86::FeatureAVX512)
+    if (STI.getFeatureBits()[X86::FeatureAVX512])
       return ParseRoundingModeOp(Start, End);
     return ErrorOperand(Start, "unknown token in expression");
   }
@@ -1764,7 +1765,7 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseATTOperand() {
 bool X86AsmParser::HandleAVX512Operand(OperandVector &Operands,
                                        const MCParsedAsmOperand &Op) {
   MCAsmParser &Parser = getParser();
-  if(STI.getFeatureBits() & X86::FeatureAVX512) {
+  if(STI.getFeatureBits()[X86::FeatureAVX512]) {
     if (getLexer().is(AsmToken::LCurly)) {
       // Eat "{" and mark the current place.
       const SMLoc consumedToken = consumeToken();

diff --git a/llvm/lib/Target/X86/Disassembler/X86Disassembler.cpp b/llvm/lib/Target/X86/Disassembler/X86Disassembler.cpp
@@ -80,20 +80,19 @@ X86GenericDisassembler::X86GenericDisassembler(
                                          MCContext &Ctx,
                                          std::unique_ptr<const MCInstrInfo> MII)
   : MCDisassembler(STI, Ctx), MII(std::move(MII)) {
-  switch (STI.getFeatureBits() &
-          (X86::Mode16Bit | X86::Mode32Bit | X86::Mode64Bit)) {
-  case X86::Mode16Bit:
+  const FeatureBitset &FB = STI.getFeatureBits();
+  if (FB[X86::Mode16Bit]) {
     fMode = MODE_16BIT;
-    break;
-  case X86::Mode32Bit:
+    return;
+  } else if (FB[X86::Mode32Bit]) {
     fMode = MODE_32BIT;
-    break;
-  case X86::Mode64Bit:
+    return;
+  } else if (FB[X86::Mode64Bit]) {
     fMode = MODE_64BIT;
-    break;
-  default:
-    llvm_unreachable("Invalid CPU mode");
+    return;
   }
+
+  llvm_unreachable("Invalid CPU mode");
 }
 
 struct Region {

diff --git a/llvm/lib/Target/X86/InstPrinter/X86ATTInstPrinter.cpp b/llvm/lib/Target/X86/InstPrinter/X86ATTInstPrinter.cpp
@@ -57,7 +57,7 @@ void X86ATTInstPrinter::printInst(const MCInst *MI, raw_ostream &OS,
   // InstrInfo.td as soon as Requires clause is supported properly
   // for InstAlias.
   if (MI->getOpcode() == X86::CALLpcrel32 &&
-      (STI.getFeatureBits() & X86::Mode64Bit) != 0) {
+      (STI.getFeatureBits()[X86::Mode64Bit])) {
     OS << "\tcallq\t";
     printPCRelImm(MI, 0, OS);
   }

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -42,15 +42,15 @@ class X86MCCodeEmitter : public MCCodeEmitter {
   ~X86MCCodeEmitter() override {}
 
   bool is64BitMode(const MCSubtargetInfo &STI) const {
-    return (STI.getFeatureBits() & X86::Mode64Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode64Bit];
   }
 
   bool is32BitMode(const MCSubtargetInfo &STI) const {
-    return (STI.getFeatureBits() & X86::Mode32Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode32Bit];
   }
 
   bool is16BitMode(const MCSubtargetInfo &STI) const {
-    return (STI.getFeatureBits() & X86::Mode16Bit) != 0;
+    return STI.getFeatureBits()[X86::Mode16Bit];
   }
 
   /// Is16BitMemOperand - Return true if the specified instruction has

diff --git a/llvm/test/TableGen/AsmPredicateCondsEmission.td b/llvm/test/TableGen/AsmPredicateCondsEmission.td
@@ -28,4 +28,4 @@ def foo : Instruction {
   let Predicates = [Pred1, Pred2];
 }
 
-// CHECK: return ((Bits & arch::AssemblerCondition2));
+// CHECK: return (Bits[arch::AssemblerCondition2]);
diff --git a/llvm/utils/TableGen/AsmMatcherEmitter.cpp b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
@@ -2248,7 +2248,7 @@ static void emitComputeAvailableFeatures(AsmMatcherInfo &Info,
     Info.AsmParser->getValueAsString("AsmParserClassName");
 
   OS << "uint64_t " << Info.Target.getName() << ClassName << "::\n"
-     << "ComputeAvailableFeatures(uint64_t FB) const {\n";
+     << "ComputeAvailableFeatures(const FeatureBitset& FB) const {\n";
   OS << "  uint64_t Features = 0;\n";
   for (const auto &SF : Info.SubtargetFeatures) {
     const SubtargetFeatureInfo &SFI = SF.second;
@@ -2270,12 +2270,10 @@ static void emitComputeAvailableFeatures(AsmMatcherInfo &Info,
         Cond = Cond.substr(1);
       }
 
-      OS << "((FB & " << Info.Target.getName() << "::" << Cond << ")";
+      OS << "(";
       if (Neg)
-        OS << " == 0";
-      else
-        OS << " != 0";
-      OS << ")";
+        OS << "!";
+      OS << "FB[" << Info.Target.getName() << "::" << Cond << "])";
 
       if (Comma.second.empty())
         break;
@@ -2645,7 +2643,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   OS << "#undef GET_ASSEMBLER_HEADER\n";
   OS << "  // This should be included into the middle of the declaration of\n";
   OS << "  // your subclasses implementation of MCTargetAsmParser.\n";
-  OS << "  uint64_t ComputeAvailableFeatures(uint64_t FeatureBits) const;\n";
+  OS << "  uint64_t ComputeAvailableFeatures(const FeatureBitset& FB) const;\n";
   OS << "  void convertToMCInst(unsigned Kind, MCInst &Inst, "
      << "unsigned Opcode,\n"
      << "                       const OperandVector "

diff --git a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
@@ -848,7 +848,7 @@ emitPredicateFunction(formatted_raw_ostream &OS, PredicateSet &Predicates,
   // The predicate function is just a big switch statement based on the
   // input predicate index.
   OS.indent(Indentation) << "static bool checkDecoderPredicate(unsigned Idx, "
-    << "uint64_t Bits) {\n";
+    << "const FeatureBitset& Bits) {\n";
   Indentation += 2;
   if (!Predicates.empty()) {
     OS.indent(Indentation) << "switch (Idx) {\n";
@@ -1102,10 +1102,10 @@ unsigned FilterChooser::getDecoderIndex(DecoderSet &Decoders,
 static void emitSinglePredicateMatch(raw_ostream &o, StringRef str,
                                      const std::string &PredicateNamespace) {
   if (str[0] == '!')
-    o << "!(Bits & " << PredicateNamespace << "::"
-      << str.slice(1,str.size()) << ")";
+    o << "!Bits[" << PredicateNamespace << "::"
+      << str.slice(1,str.size()) << "]";
   else
-    o << "(Bits & " << PredicateNamespace << "::" << str << ")";
+    o << "Bits[" << PredicateNamespace << "::" << str << "]";
 }
 
 bool FilterChooser::emitPredicateMatch(raw_ostream &o, unsigned &Indentation,
@@ -2012,7 +2012,7 @@ static void emitDecodeInstruction(formatted_raw_ostream &OS) {
      << "                                      InsnType insn, uint64_t Address,\n"
      << "                                      const void *DisAsm,\n"
      << "                                      const MCSubtargetInfo &STI) {\n"
-     << "  uint64_t Bits = STI.getFeatureBits();\n"
+     << "  const FeatureBitset& Bits = STI.getFeatureBits();\n"
      << "\n"
      << "  const uint8_t *Ptr = DecodeTable;\n"
      << "  uint32_t CurFieldValue = 0;\n"

diff --git a/llvm/utils/TableGen/InstrInfoEmitter.cpp b/llvm/utils/TableGen/InstrInfoEmitter.cpp
@@ -549,15 +549,15 @@ void InstrInfoEmitter::emitRecord(const CodeGenInstruction &Inst, unsigned Num,
   CodeGenTarget &Target = CDP.getTargetInfo();
   if (Inst.HasComplexDeprecationPredicate)
     // Emit a function pointer to the complex predicate method.
-    OS << ",0"
+    OS << ", -1 "
        << ",&get" << Inst.DeprecatedReason << "DeprecationInfo";
   else if (!Inst.DeprecatedReason.empty())
     // Emit the Subtarget feature.
-    OS << "," << Target.getInstNamespace() << "::" << Inst.DeprecatedReason
-       << ",nullptr";
+    OS << ", " << Target.getInstNamespace() << "::" << Inst.DeprecatedReason
+       << " ,nullptr";
   else
     // Instruction isn't deprecated.
-    OS << ",0,nullptr";
+    OS << ", -1 ,nullptr";
 
   OS << " },  // Inst #" << Num << " = " << Inst.TheDef->getName() << "\n";
 }

diff --git a/llvm/utils/TableGen/SubtargetEmitter.cpp b/llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/MC/MCInstrItineraries.h"
+#include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Format.h"
 #include "llvm/TableGen/Error.h"
@@ -62,7 +63,7 @@ class SubtargetEmitter {
   CodeGenSchedModels &SchedModels;
   std::string Target;
 
-  void Enumeration(raw_ostream &OS, const char *ClassName, bool isBits);
+  void Enumeration(raw_ostream &OS, const char *ClassName);
   unsigned FeatureKeyValues(raw_ostream &OS);
   unsigned CPUKeyValues(raw_ostream &OS);
   void FormItineraryStageString(const std::string &Names,
@@ -112,17 +113,16 @@ class SubtargetEmitter {
 // Enumeration - Emit the specified class as an enumeration.
 //
 void SubtargetEmitter::Enumeration(raw_ostream &OS,
-                                   const char *ClassName,
-                                   bool isBits) {
+                                   const char *ClassName) {
   // Get all records of class and sort
   std::vector<Record*> DefList = Records.getAllDerivedDefinitions(ClassName);
   std::sort(DefList.begin(), DefList.end(), LessRecord());
 
   unsigned N = DefList.size();
   if (N == 0)
     return;
-  if (N > 64)
-    PrintFatalError("Too many (> 64) subtarget features!");
+  if (N > MAX_SUBTARGET_FEATURES)
+    PrintFatalError("Too many subtarget features! Bump MAX_SUBTARGET_FEATURES.");
 
   OS << "namespace " << Target << " {\n";
 
@@ -135,21 +135,14 @@ void SubtargetEmitter::Enumeration(raw_ostream &OS,
     Record *Def = DefList[i];
 
     // Get and emit name
-    OS << "  " << Def->getName();
-
-    // If bit flags then emit expression (1 << i)
-    if (isBits)  OS << " = " << " 1ULL << " << i;
-
-    // Depending on 'if more in the list' emit comma
+    OS << "  " << Def->getName() << " = " << i;
     if (++i < N) OS << ",";
 
     OS << "\n";
   }
 
-  // Close enumeration
-  OS << "};\n";
-
-  OS << "}\n";
+  // Close enumeration and namespace
+  OS << "};\n}\n";
 }
 
 //
@@ -183,22 +176,24 @@ unsigned SubtargetEmitter::FeatureKeyValues(raw_ostream &OS) {
 
     if (CommandLineName.empty()) continue;
 
-    // Emit as { "feature", "description", featureEnum, i1 | i2 | ... | in }
+    // Emit as { "feature", "description", { featureEnum }, { i1 , i2 , ... , in } }
     OS << "  { "
        << "\"" << CommandLineName << "\", "
        << "\"" << Desc << "\", "
-       << Target << "::" << Name << ", ";
+       << "{ " << Target << "::" << Name << " }, ";
 
     const std::vector<Record*> &ImpliesList =
       Feature->getValueAsListOfDefs("Implies");
 
     if (ImpliesList.empty()) {
-      OS << "0ULL";
+      OS << "{ }";
     } else {
+      OS << "{ ";
       for (unsigned j = 0, M = ImpliesList.size(); j < M;) {
         OS << Target << "::" << ImpliesList[j]->getName();
-        if (++j < M) OS << " | ";
+        if (++j < M) OS << ", ";
       }
+      OS << " }";
     }
 
     OS << " }";
@@ -240,22 +235,24 @@ unsigned SubtargetEmitter::CPUKeyValues(raw_ostream &OS) {
     const std::vector<Record*> &FeatureList =
       Processor->getValueAsListOfDefs("Features");
 
-    // Emit as { "cpu", "description", f1 | f2 | ... fn },
+    // Emit as { "cpu", "description", { f1 , f2 , ... fn } },
     OS << "  { "
        << "\"" << Name << "\", "
        << "\"Select the " << Name << " processor\", ";
 
     if (FeatureList.empty()) {
-      OS << "0ULL";
+      OS << "{ }";
     } else {
+      OS << "{ ";
       for (unsigned j = 0, M = FeatureList.size(); j < M;) {
         OS << Target << "::" << FeatureList[j]->getName();
-        if (++j < M) OS << " | ";
+        if (++j < M) OS << ", ";
       }
+      OS << " }";
     }
 
-    // The "0" is for the "implies" section of this data structure.
-    OS << ", 0ULL }";
+    // The { } is for the "implies" section of this data structure.
+    OS << ", { } }";
 
     // Depending on 'if more in the list' emit comma
     if (++i < N) OS << ",";
@@ -1383,7 +1380,7 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
   }
 
   OS << "  InitMCProcessorInfo(CPU, FS);\n"
-     << "  uint64_t Bits = getFeatureBits();\n";
+     << "  const FeatureBitset& Bits = getFeatureBits();\n";
 
   for (unsigned i = 0; i < Features.size(); i++) {
     // Next record
@@ -1393,12 +1390,12 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
     const std::string &Attribute = R->getValueAsString("Attribute");
 
     if (Value=="true" || Value=="false")
-      OS << "  if ((Bits & " << Target << "::"
-         << Instance << ") != 0) "
+      OS << "  if (Bits[" << Target << "::"
+         << Instance << "]) "
          << Attribute << " = " << Value << ";\n";
     else
-      OS << "  if ((Bits & " << Target << "::"
-         << Instance << ") != 0 && "
+      OS << "  if (Bits[" << Target << "::"
+         << Instance << "] && "
          << Attribute << " < " << Value << ") "
          << Attribute << " = " << Value << ";\n";
   }
@@ -1416,7 +1413,7 @@ void SubtargetEmitter::run(raw_ostream &OS) {
   OS << "#undef GET_SUBTARGETINFO_ENUM\n";
 
   OS << "namespace llvm {\n";
-  Enumeration(OS, "SubtargetFeature", true);
+  Enumeration(OS, "SubtargetFeature");
   OS << "} // End llvm namespace \n";
   OS << "#endif // GET_SUBTARGETINFO_ENUM\n\n";