diff --git a/utils/TableGen/AsmMatcherEmitter.cpp b/utils/TableGen/AsmMatcherEmitter.cpp
index 7b438842418..cdcc496e7d4 100644
--- a/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/utils/TableGen/AsmMatcherEmitter.cpp
@@ -2023,40 +2023,48 @@ static void EmitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
   // Emit the static custom operand parsing table;
   OS << "namespace {\n";
   OS << "  struct OperandMatchEntry {\n";
-  OS << "    const char *Mnemonic;\n";
+  OS << "    static const char *MnemonicTable;\n";
   OS << "    unsigned OperandMask;\n";
-  OS << "    MatchClassKind Class;\n";
-  OS << "    unsigned RequiredFeatures;\n";
+  OS << "    uint16_t Mnemonic;\n";
+  OS << "    " << getMinimalTypeForRange(Info.Classes.size())
+               << " Class;\n";
+  OS << "    " << getMinimalTypeForRange(1ULL << Info.SubtargetFeatures.size())
+               << " RequiredFeatures;\n\n";
+  OS << "    StringRef getMnemonic() const {\n";
+  OS << "      return StringRef(MnemonicTable + Mnemonic + 1,\n";
+  OS << "                       MnemonicTable[Mnemonic]);\n";
+  OS << "    }\n";
   OS << "  };\n\n";
 
   OS << "  // Predicate for searching for an opcode.\n";
   OS << "  struct LessOpcodeOperand {\n";
   OS << "    bool operator()(const OperandMatchEntry &LHS, StringRef RHS) {\n";
-  OS << "      return StringRef(LHS.Mnemonic) < RHS;\n";
+  OS << "      return LHS.getMnemonic()  < RHS;\n";
   OS << "    }\n";
   OS << "    bool operator()(StringRef LHS, const OperandMatchEntry &RHS) {\n";
-  OS << "      return LHS < StringRef(RHS.Mnemonic);\n";
+  OS << "      return LHS < RHS.getMnemonic();\n";
   OS << "    }\n";
   OS << "    bool operator()(const OperandMatchEntry &LHS,";
   OS << " const OperandMatchEntry &RHS) {\n";
-  OS << "      return StringRef(LHS.Mnemonic) < StringRef(RHS.Mnemonic);\n";
+  OS << "      return LHS.getMnemonic() < RHS.getMnemonic();\n";
   OS << "    }\n";
   OS << "  };\n";
 
   OS << "} // end anonymous namespace.\n\n";
 
+  StringToOffsetTable StringTable;
+
   OS << "static const OperandMatchEntry OperandMatchTable["
      << Info.OperandMatchInfo.size() << "] = {\n";
 
-  OS << "  /* Mnemonic, Operand List Mask, Operand Class, Features */\n";
+  OS << "  /* Operand List Mask, Mnemonic, Operand Class, Features */\n";
   for (std::vector<OperandMatchEntry>::const_iterator it =
        Info.OperandMatchInfo.begin(), ie = Info.OperandMatchInfo.end();
        it != ie; ++it) {
     const OperandMatchEntry &OMI = *it;
     const MatchableInfo &II = *OMI.MI;
 
-    OS << "  { \"" << II.Mnemonic << "\""
-       << ", " << OMI.OperandMask;
+    OS << "  { " << OMI.OperandMask;
 
     OS << " /* ";
     bool printComma = false;
@@ -2069,6 +2077,11 @@ static void EmitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
       }
     OS << " */";
 
+    // Store a pascal-style length byte in the mnemonic.
+    std::string LenMnemonic = char(II.Mnemonic.size()) + II.Mnemonic.str();
+    OS << ", " << StringTable.GetOrAddStringOffset(LenMnemonic, false)
+       << " /* " << II.Mnemonic << " */";
+
     OS << ", " << OMI.CI->Name
        << ", ";
 
@@ -2084,6 +2097,10 @@ static void EmitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
   }
   OS << "};\n\n";
 
+  OS << "const char *OperandMatchEntry::MnemonicTable =\n";
+  StringTable.EmitString(OS);
+  OS << ";\n\n";
+
   // Emit the operand class switch to call the correct custom parser for
   // the found operand class.
   OS << Target.getName() << ClassName << "::OperandMatchResultTy "
@@ -2137,7 +2154,7 @@ static void EmitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
      << "       *ie = MnemonicRange.second; it != ie; ++it) {\n";
 
   OS << "    // equal_range guarantees that instruction mnemonic matches.\n";
-  OS << "    assert(Mnemonic == it->Mnemonic);\n\n";
+  OS << "    assert(Mnemonic == it->getMnemonic());\n\n";
 
   // Emit check that the required features are available.
   OS << "    // check if the available features match\n";
@@ -2349,6 +2366,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
     OS << "  { " << Target.getName() << "::"
        << II.getResultInst()->TheDef->getName() << ", "
        << StringTable.GetOrAddStringOffset(LenMnemonic, false)
+       << " /* " << II.Mnemonic << " */"
        << ", " << II.ConversionFnKind << ", { ";
     for (unsigned i = 0, e = II.AsmOperands.size(); i != e; ++i) {
       MatchableInfo::AsmOperand &Op = II.AsmOperands[i];