Index: llvm/include/llvm/TableGen/Record.h
===================================================================
--- llvm/include/llvm/TableGen/Record.h
+++ llvm/include/llvm/TableGen/Record.h
@@ -1703,6 +1703,7 @@
 
   std::string InputFilename;
   RecordMap Classes, Defs;
+  mutable StringMap<std::vector<Record *>> ClassRecordsMap;
   FoldingSet<RecordRecTy> RecordTypePool;
   std::map<std::string, Init *, std::less<>> ExtraGlobals;
   unsigned AnonCounter = 0;
@@ -1801,17 +1802,14 @@
   //===--------------------------------------------------------------------===//
   // High-level helper methods, useful for tablegen backends.
 
-  /// Get all the concrete records that inherit from all the specified
-  /// classes. The classes must be defined.
-  std::vector<Record *> getAllDerivedDefinitions(
-      const ArrayRef<StringRef> ClassNames) const;
-
   /// Get all the concrete records that inherit from the one specified
   /// class. The class must be defined.
-  std::vector<Record *> getAllDerivedDefinitions(StringRef ClassName) const {
+  std::vector<Record *> getAllDerivedDefinitions(StringRef ClassName) const;
 
-    return getAllDerivedDefinitions(makeArrayRef(ClassName));
-  }
+  /// Get all the concrete records that inherit from all the specified
+  /// classes. The classes must be defined.
+  std::vector<Record *> getAllDerivedDefinitions(
+      ArrayRef<StringRef> ClassNames) const;
 
   void dump() const;
 };
Index: llvm/lib/TableGen/Record.cpp
===================================================================
--- llvm/lib/TableGen/Record.cpp
+++ llvm/lib/TableGen/Record.cpp
@@ -2595,8 +2595,20 @@
   }
 }
 
+// We cache the record vectors for single classes. Many backends request
+// the same vectors multiple times.
 std::vector<Record *> RecordKeeper::getAllDerivedDefinitions(
-    const ArrayRef<StringRef> ClassNames) const {
+    StringRef ClassName) const {
+
+  auto Pair = ClassRecordsMap.try_emplace(ClassName);
+  if (Pair.second)
+    Pair.first->second = getAllDerivedDefinitions(makeArrayRef(ClassName));
+
+  return Pair.first->second;
+}
+
+std::vector<Record *> RecordKeeper::getAllDerivedDefinitions(
+    ArrayRef<StringRef> ClassNames) const {
   SmallVector<Record *, 2> ClassRecs;
   std::vector<Record *> Defs;
 
Index: llvm/utils/TableGen/InstrInfoEmitter.cpp
===================================================================
--- llvm/utils/TableGen/InstrInfoEmitter.cpp
+++ llvm/utils/TableGen/InstrInfoEmitter.cpp
@@ -532,6 +532,7 @@
   unsigned ListNumber = 0;
 
   // Emit all of the instruction's implicit uses and defs.
+  Records.startTimer("Emit uses/defs");
   for (const CodeGenInstruction *II : Target.getInstructionsByEnumValue()) {
     Record *Inst = II->TheDef;
     std::vector<Record*> Uses = Inst->getValueAsListOfDefs("Uses");
@@ -549,10 +550,12 @@
   OperandInfoMapTy OperandInfoIDs;
 
   // Emit all of the operand info records.
+  Records.startTimer("Emit operand info");
   EmitOperandInfo(OS, OperandInfoIDs);
 
   // Emit all of the MCInstrDesc records in their ENUM ordering.
   //
+  Records.startTimer("Emit InstrDesc records");
   OS << "\nextern const MCInstrDesc " << TargetName << "Insts[] = {\n";
   ArrayRef<const CodeGenInstruction*> NumberedInstructions =
     Target.getInstructionsByEnumValue();
@@ -568,6 +571,7 @@
   OS << "};\n\n";
 
   // Emit the array of instruction names.
+  Records.startTimer("Emit instruction names");
   InstrNames.layout();
   InstrNames.emitStringLiteralDef(OS, Twine("extern const char ") + TargetName +
                                           "InstrNameData[]");
@@ -628,6 +632,7 @@
   }
 
   // MCInstrInfo initialization routine.
+  Records.startTimer("Emit initialization routine");
   OS << "static inline void Init" << TargetName
      << "MCInstrInfo(MCInstrInfo *II) {\n";
   OS << "  II->InitMCInstrInfo(" << TargetName << "Insts, " << TargetName
@@ -706,10 +711,13 @@
 
   OS << "#endif // GET_INSTRINFO_CTOR_DTOR\n\n";
 
+  Records.startTimer("Emit operand name mappings");
   emitOperandNameMappings(OS, Target, NumberedInstructions);
 
+  Records.startTimer("Emit operand type mappings");
   emitOperandTypeMappings(OS, Target, NumberedInstructions);
 
+  Records.startTimer("Emit helper methods");
   emitMCIIHelperMethods(OS, TargetName);
 }
 
@@ -862,7 +870,9 @@
 namespace llvm {
 
 void EmitInstrInfo(RecordKeeper &RK, raw_ostream &OS) {
+  RK.startTimer("Analyze DAG patterns");
   InstrInfoEmitter(RK).run(OS);
+  RK.startTimer("Emit map table");
   EmitMapTable(RK, OS);
 }