diff --git a/llvm/include/llvm/IR/InlineAsm.h b/llvm/include/llvm/IR/InlineAsm.h
index ac190892bab0..b2d79d0f0bfc 100644
--- a/llvm/include/llvm/IR/InlineAsm.h
+++ b/llvm/include/llvm/IR/InlineAsm.h
@@ -25,12 +25,9 @@ namespace llvm {
 class PointerType;
 class FunctionType;
 class Module;
+
 struct InlineAsmKeyType;
-template<class ValType, class ValRefType, class TypeClass, class ConstantClass,
-         bool HasLargeKey>
-class ConstantUniqueMap;
-template<class ConstantClass, class TypeClass, class ValType>
-struct ConstantCreator;
+template <class ConstantClass> class ConstantUniqueMap;
 
 class InlineAsm : public Value {
 public:
@@ -40,9 +37,8 @@ public:
   };
 
 private:
-  friend struct ConstantCreator<InlineAsm, PointerType, InlineAsmKeyType>;
-  friend class ConstantUniqueMap<InlineAsmKeyType, const InlineAsmKeyType&,
-                                 PointerType, InlineAsm, false>;
+  friend struct InlineAsmKeyType;
+  friend class ConstantUniqueMap<InlineAsm>;
 
   InlineAsm(const InlineAsm &) LLVM_DELETED_FUNCTION;
   void operator=(const InlineAsm&) LLVM_DELETED_FUNCTION;
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 45a71dc62301..c9ce2e826b92 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -1507,7 +1507,7 @@ static inline Constant *getFoldedCast(
   LLVMContextImpl *pImpl = Ty->getContext().pImpl;
 
   // Look up the constant in the table first to ensure uniqueness.
-  ExprMapKeyType Key(opc, C);
+  ConstantExprKeyType Key(opc, C);
 
   return pImpl->ExprConstants.getOrCreate(Ty, Key);
 }
@@ -1842,7 +1842,7 @@ Constant *ConstantExpr::get(unsigned Opcode, Constant *C1, Constant *C2,
     return FC;          // Fold a few common cases.
 
   Constant *ArgVec[] = { C1, C2 };
-  ExprMapKeyType Key(Opcode, ArgVec, 0, Flags);
+  ConstantExprKeyType Key(Opcode, ArgVec, 0, Flags);
 
   LLVMContextImpl *pImpl = C1->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(C1->getType(), Key);
@@ -1919,7 +1919,7 @@ Constant *ConstantExpr::getSelect(Constant *C, Constant *V1, Constant *V2) {
     return SC;        // Fold common cases
 
   Constant *ArgVec[] = { C, V1, V2 };
-  ExprMapKeyType Key(Instruction::Select, ArgVec);
+  ConstantExprKeyType Key(Instruction::Select, ArgVec);
 
   LLVMContextImpl *pImpl = C->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(V1->getType(), Key);
@@ -1954,8 +1954,8 @@ Constant *ConstantExpr::getGetElementPtr(Constant *C, ArrayRef<Value *> Idxs,
            "getelementptr index type missmatch");
     ArgVec.push_back(cast<Constant>(Idxs[i]));
   }
-  const ExprMapKeyType Key(Instruction::GetElementPtr, ArgVec, 0,
-                           InBounds ? GEPOperator::IsInBounds : 0);
+  const ConstantExprKeyType Key(Instruction::GetElementPtr, ArgVec, 0,
+                                InBounds ? GEPOperator::IsInBounds : 0);
 
   LLVMContextImpl *pImpl = C->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ReqTy, Key);
@@ -1973,7 +1973,7 @@ ConstantExpr::getICmp(unsigned short pred, Constant *LHS, Constant *RHS) {
   // Look up the constant in the table first to ensure uniqueness
   Constant *ArgVec[] = { LHS, RHS };
   // Get the key type with both the opcode and predicate
-  const ExprMapKeyType Key(Instruction::ICmp, ArgVec, pred);
+  const ConstantExprKeyType Key(Instruction::ICmp, ArgVec, pred);
 
   Type *ResultTy = Type::getInt1Ty(LHS->getContext());
   if (VectorType *VT = dyn_cast<VectorType>(LHS->getType()))
@@ -1994,7 +1994,7 @@ ConstantExpr::getFCmp(unsigned short pred, Constant *LHS, Constant *RHS) {
   // Look up the constant in the table first to ensure uniqueness
   Constant *ArgVec[] = { LHS, RHS };
   // Get the key type with both the opcode and predicate
-  const ExprMapKeyType Key(Instruction::FCmp, ArgVec, pred);
+  const ConstantExprKeyType Key(Instruction::FCmp, ArgVec, pred);
 
   Type *ResultTy = Type::getInt1Ty(LHS->getContext());
   if (VectorType *VT = dyn_cast<VectorType>(LHS->getType()))
@@ -2015,7 +2015,7 @@ Constant *ConstantExpr::getExtractElement(Constant *Val, Constant *Idx) {
 
   // Look up the constant in the table first to ensure uniqueness
   Constant *ArgVec[] = { Val, Idx };
-  const ExprMapKeyType Key(Instruction::ExtractElement, ArgVec);
+  const ConstantExprKeyType Key(Instruction::ExtractElement, ArgVec);
 
   LLVMContextImpl *pImpl = Val->getContext().pImpl;
   Type *ReqTy = Val->getType()->getVectorElementType();
@@ -2035,7 +2035,7 @@ Constant *ConstantExpr::getInsertElement(Constant *Val, Constant *Elt,
     return FC;          // Fold a few common cases.
   // Look up the constant in the table first to ensure uniqueness
   Constant *ArgVec[] = { Val, Elt, Idx };
-  const ExprMapKeyType Key(Instruction::InsertElement, ArgVec);
+  const ConstantExprKeyType Key(Instruction::InsertElement, ArgVec);
 
   LLVMContextImpl *pImpl = Val->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(Val->getType(), Key);
@@ -2055,7 +2055,7 @@ Constant *ConstantExpr::getShuffleVector(Constant *V1, Constant *V2,
 
   // Look up the constant in the table first to ensure uniqueness
   Constant *ArgVec[] = { V1, V2, Mask };
-  const ExprMapKeyType Key(Instruction::ShuffleVector, ArgVec);
+  const ConstantExprKeyType Key(Instruction::ShuffleVector, ArgVec);
 
   LLVMContextImpl *pImpl = ShufTy->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ShufTy, Key);
@@ -2075,7 +2075,7 @@ Constant *ConstantExpr::getInsertValue(Constant *Agg, Constant *Val,
     return FC;
 
   Constant *ArgVec[] = { Agg, Val };
-  const ExprMapKeyType Key(Instruction::InsertValue, ArgVec, 0, 0, Idxs);
+  const ConstantExprKeyType Key(Instruction::InsertValue, ArgVec, 0, 0, Idxs);
 
   LLVMContextImpl *pImpl = Agg->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ReqTy, Key);
@@ -2096,7 +2096,7 @@ Constant *ConstantExpr::getExtractValue(Constant *Agg,
     return FC;
 
   Constant *ArgVec[] = { Agg };
-  const ExprMapKeyType Key(Instruction::ExtractValue, ArgVec, 0, 0, Idxs);
+  const ConstantExprKeyType Key(Instruction::ExtractValue, ArgVec, 0, 0, Idxs);
 
   LLVMContextImpl *pImpl = Agg->getContext().pImpl;
   return pImpl->ExprConstants.getOrCreate(ReqTy, Key);
diff --git a/llvm/lib/IR/ConstantsContext.h b/llvm/lib/IR/ConstantsContext.h
index c3aefb9ce2da..f9485f1f38cc 100644
--- a/llvm/lib/IR/ConstantsContext.h
+++ b/llvm/lib/IR/ConstantsContext.h
@@ -314,66 +314,148 @@ struct OperandTraits<CompareConstantExpr> :
 };
 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(CompareConstantExpr, Value)
 
-struct ExprMapKeyType {
-  ExprMapKeyType(unsigned opc,
-      ArrayRef<Constant*> ops,
-      unsigned short flags = 0,
-      unsigned short optionalflags = 0,
-      ArrayRef<unsigned> inds = None)
-        : opcode(opc), subclassoptionaldata(optionalflags), subclassdata(flags),
-        operands(ops.begin(), ops.end()), indices(inds.begin(), inds.end()) {}
-  uint8_t opcode;
-  uint8_t subclassoptionaldata;
-  uint16_t subclassdata;
-  std::vector<Constant*> operands;
-  SmallVector<unsigned, 4> indices;
-  bool operator==(const ExprMapKeyType& that) const {
-    return this->opcode == that.opcode &&
-           this->subclassdata == that.subclassdata &&
-           this->subclassoptionaldata == that.subclassoptionaldata &&
-           this->operands == that.operands &&
-           this->indices == that.indices;
-  }
-  bool operator<(const ExprMapKeyType & that) const {
-    return std::tie(opcode, operands, subclassdata, subclassoptionaldata,
-                    indices) <
-           std::tie(that.opcode, that.operands, that.subclassdata,
-                    that.subclassoptionaldata, that.indices);
-  }
+struct InlineAsmKeyType;
+struct ConstantExprKeyType;
 
-  bool operator!=(const ExprMapKeyType& that) const {
-    return !(*this == that);
-  }
+template <class ConstantClass> struct ConstantInfo;
+template <> struct ConstantInfo<ConstantExpr> {
+  typedef ConstantExprKeyType ValType;
+  typedef Type TypeClass;
+};
+template <> struct ConstantInfo<InlineAsm> {
+  typedef InlineAsmKeyType ValType;
+  typedef PointerType TypeClass;
 };
 
 struct InlineAsmKeyType {
-  InlineAsmKeyType(StringRef AsmString,
-                   StringRef Constraints, bool hasSideEffects,
-                   bool isAlignStack, InlineAsm::AsmDialect asmDialect)
-    : asm_string(AsmString), constraints(Constraints),
-      has_side_effects(hasSideEffects), is_align_stack(isAlignStack),
-      asm_dialect(asmDialect) {}
-  std::string asm_string;
-  std::string constraints;
-  bool has_side_effects;
-  bool is_align_stack;
-  InlineAsm::AsmDialect asm_dialect;
-  bool operator==(const InlineAsmKeyType& that) const {
-    return this->asm_string == that.asm_string &&
-           this->constraints == that.constraints &&
-           this->has_side_effects == that.has_side_effects &&
-           this->is_align_stack == that.is_align_stack &&
-           this->asm_dialect == that.asm_dialect;
+  StringRef AsmString;
+  StringRef Constraints;
+  bool HasSideEffects;
+  bool IsAlignStack;
+  InlineAsm::AsmDialect AsmDialect;
+
+  InlineAsmKeyType(StringRef AsmString, StringRef Constraints,
+                   bool HasSideEffects, bool IsAlignStack,
+                   InlineAsm::AsmDialect AsmDialect)
+      : AsmString(AsmString), Constraints(Constraints),
+        HasSideEffects(HasSideEffects), IsAlignStack(IsAlignStack),
+        AsmDialect(AsmDialect) {}
+  InlineAsmKeyType(const InlineAsm *Asm, SmallVectorImpl<Constant *> &)
+      : AsmString(Asm->getAsmString()), Constraints(Asm->getConstraintString()),
+        HasSideEffects(Asm->hasSideEffects()),
+        IsAlignStack(Asm->isAlignStack()), AsmDialect(Asm->getDialect()) {}
+
+  bool operator==(const InlineAsmKeyType &X) const {
+    return HasSideEffects == X.HasSideEffects &&
+           IsAlignStack == X.IsAlignStack && AsmDialect == X.AsmDialect &&
+           AsmString == X.AsmString && Constraints == X.Constraints;
   }
-  bool operator<(const InlineAsmKeyType& that) const {
-    return std::tie(asm_string, constraints, has_side_effects, is_align_stack,
-                    asm_dialect) <
-           std::tie(that.asm_string, that.constraints, that.has_side_effects,
-                    that.is_align_stack, that.asm_dialect);
+  bool operator==(const InlineAsm *Asm) const {
+    return HasSideEffects == Asm->hasSideEffects() &&
+           IsAlignStack == Asm->isAlignStack() &&
+           AsmDialect == Asm->getDialect() &&
+           AsmString == Asm->getAsmString() &&
+           Constraints == Asm->getConstraintString();
+  }
+  unsigned getHash() const {
+    return hash_combine(AsmString, Constraints, HasSideEffects, IsAlignStack,
+                        AsmDialect);
   }
 
-  bool operator!=(const InlineAsmKeyType& that) const {
-    return !(*this == that);
+  typedef typename ConstantInfo<InlineAsm>::TypeClass TypeClass;
+  InlineAsm *create(TypeClass *Ty) const {
+    return new InlineAsm(Ty, AsmString, Constraints, HasSideEffects,
+                         IsAlignStack, AsmDialect);
+  }
+};
+
+struct ConstantExprKeyType {
+  uint8_t Opcode;
+  uint8_t SubclassOptionalData;
+  uint16_t SubclassData;
+  ArrayRef<Constant *> Ops;
+  ArrayRef<unsigned> Indexes;
+
+  ConstantExprKeyType(unsigned Opcode, ArrayRef<Constant *> Ops,
+                      unsigned short SubclassData = 0,
+                      unsigned short SubclassOptionalData = 0,
+                      ArrayRef<unsigned> Indexes = None)
+      : Opcode(Opcode), SubclassOptionalData(SubclassOptionalData),
+        SubclassData(SubclassData), Ops(Ops), Indexes(Indexes) {}
+  ConstantExprKeyType(const ConstantExpr *CE,
+                      SmallVectorImpl<Constant *> &Storage)
+      : Opcode(CE->getOpcode()),
+        SubclassOptionalData(CE->getRawSubclassOptionalData()),
+        SubclassData(CE->isCompare() ? CE->getPredicate() : 0),
+        Indexes(CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()) {
+    assert(Storage.empty() && "Expected empty storage");
+    for (unsigned I = 0, E = CE->getNumOperands(); I != E; ++I)
+      Storage.push_back(CE->getOperand(I));
+    Ops = Storage;
+  }
+
+  bool operator==(const ConstantExprKeyType &X) const {
+    return Opcode == X.Opcode && SubclassData == X.SubclassData &&
+           SubclassOptionalData == X.SubclassOptionalData && Ops == X.Ops &&
+           Indexes == X.Indexes;
+  }
+
+  bool operator==(const ConstantExpr *CE) const {
+    if (Opcode != CE->getOpcode())
+      return false;
+    if (SubclassOptionalData != CE->getRawSubclassOptionalData())
+      return false;
+    if (Ops.size() != CE->getNumOperands())
+      return false;
+    if (SubclassData != (CE->isCompare() ? CE->getPredicate() : 0))
+      return false;
+    for (unsigned I = 0, E = Ops.size(); I != E; ++I)
+      if (Ops[I] != CE->getOperand(I))
+        return false;
+    if (Indexes != (CE->hasIndices() ? CE->getIndices() : ArrayRef<unsigned>()))
+      return false;
+    return true;
+  }
+
+  unsigned getHash() const {
+    return hash_combine(Opcode, SubclassOptionalData, SubclassData,
+                        hash_combine_range(Ops.begin(), Ops.end()),
+                        hash_combine_range(Indexes.begin(), Indexes.end()));
+  }
+
+  typedef typename ConstantInfo<ConstantExpr>::TypeClass TypeClass;
+  ConstantExpr *create(TypeClass *Ty) const {
+    switch (Opcode) {
+    default:
+      if (Instruction::isCast(Opcode))
+        return new UnaryConstantExpr(Opcode, Ops[0], Ty);
+      if ((Opcode >= Instruction::BinaryOpsBegin &&
+           Opcode < Instruction::BinaryOpsEnd))
+        return new BinaryConstantExpr(Opcode, Ops[0], Ops[1],
+                                      SubclassOptionalData);
+      llvm_unreachable("Invalid ConstantExpr!");
+    case Instruction::Select:
+      return new SelectConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::ExtractElement:
+      return new ExtractElementConstantExpr(Ops[0], Ops[1]);
+    case Instruction::InsertElement:
+      return new InsertElementConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::ShuffleVector:
+      return new ShuffleVectorConstantExpr(Ops[0], Ops[1], Ops[2]);
+    case Instruction::InsertValue:
+      return new InsertValueConstantExpr(Ops[0], Ops[1], Indexes, Ty);
+    case Instruction::ExtractValue:
+      return new ExtractValueConstantExpr(Ops[0], Indexes, Ty);
+    case Instruction::GetElementPtr:
+      return GetElementPtrConstantExpr::Create(Ops[0], Ops.slice(1), Ty,
+                                               SubclassOptionalData);
+    case Instruction::ICmp:
+      return new CompareConstantExpr(Ty, Instruction::ICmp, SubclassData,
+                                     Ops[0], Ops[1]);
+    case Instruction::FCmp:
+      return new CompareConstantExpr(Ty, Instruction::FCmp, SubclassData,
+                                     Ops[0], Ops[1]);
+    }
   }
 };
 
@@ -412,228 +494,99 @@ struct ConstantArrayCreator {
   }
 };
 
-template<class ConstantClass>
-struct ConstantKeyData {
-  typedef void ValType;
-  static ValType getValType(ConstantClass *C) {
-    llvm_unreachable("Unknown Constant type!");
-  }
-};
-
-template<>
-struct ConstantCreator<ConstantExpr, Type, ExprMapKeyType> {
-  static ConstantExpr *create(Type *Ty, const ExprMapKeyType &V,
-      unsigned short pred = 0) {
-    if (Instruction::isCast(V.opcode))
-      return new UnaryConstantExpr(V.opcode, V.operands[0], Ty);
-    if ((V.opcode >= Instruction::BinaryOpsBegin &&
-         V.opcode < Instruction::BinaryOpsEnd))
-      return new BinaryConstantExpr(V.opcode, V.operands[0], V.operands[1],
-                                    V.subclassoptionaldata);
-    if (V.opcode == Instruction::Select)
-      return new SelectConstantExpr(V.operands[0], V.operands[1], 
-                                    V.operands[2]);
-    if (V.opcode == Instruction::ExtractElement)
-      return new ExtractElementConstantExpr(V.operands[0], V.operands[1]);
-    if (V.opcode == Instruction::InsertElement)
-      return new InsertElementConstantExpr(V.operands[0], V.operands[1],
-                                           V.operands[2]);
-    if (V.opcode == Instruction::ShuffleVector)
-      return new ShuffleVectorConstantExpr(V.operands[0], V.operands[1],
-                                           V.operands[2]);
-    if (V.opcode == Instruction::InsertValue)
-      return new InsertValueConstantExpr(V.operands[0], V.operands[1],
-                                         V.indices, Ty);
-    if (V.opcode == Instruction::ExtractValue)
-      return new ExtractValueConstantExpr(V.operands[0], V.indices, Ty);
-    if (V.opcode == Instruction::GetElementPtr) {
-      std::vector<Constant*> IdxList(V.operands.begin()+1, V.operands.end());
-      return GetElementPtrConstantExpr::Create(V.operands[0], IdxList, Ty,
-                                               V.subclassoptionaldata);
-    }
-
-    // The compare instructions are weird. We have to encode the predicate
-    // value and it is combined with the instruction opcode by multiplying
-    // the opcode by one hundred. We must decode this to get the predicate.
-    if (V.opcode == Instruction::ICmp)
-      return new CompareConstantExpr(Ty, Instruction::ICmp, V.subclassdata,
-                                     V.operands[0], V.operands[1]);
-    if (V.opcode == Instruction::FCmp) 
-      return new CompareConstantExpr(Ty, Instruction::FCmp, V.subclassdata,
-                                     V.operands[0], V.operands[1]);
-    llvm_unreachable("Invalid ConstantExpr!");
-  }
-};
-
-template<>
-struct ConstantKeyData<ConstantExpr> {
-  typedef ExprMapKeyType ValType;
-  static ValType getValType(ConstantExpr *CE) {
-    std::vector<Constant*> Operands;
-    Operands.reserve(CE->getNumOperands());
-    for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
-      Operands.push_back(cast<Constant>(CE->getOperand(i)));
-    return ExprMapKeyType(CE->getOpcode(), Operands,
-        CE->isCompare() ? CE->getPredicate() : 0,
-        CE->getRawSubclassOptionalData(),
-        CE->hasIndices() ?
-          CE->getIndices() : ArrayRef<unsigned>());
-  }
-};
-
-template<>
-struct ConstantCreator<InlineAsm, PointerType, InlineAsmKeyType> {
-  static InlineAsm *create(PointerType *Ty, const InlineAsmKeyType &Key) {
-    return new InlineAsm(Ty, Key.asm_string, Key.constraints,
-                         Key.has_side_effects, Key.is_align_stack,
-                         Key.asm_dialect);
-  }
-};
-
-template<>
-struct ConstantKeyData<InlineAsm> {
-  typedef InlineAsmKeyType ValType;
-  static ValType getValType(InlineAsm *Asm) {
-    return InlineAsmKeyType(Asm->getAsmString(), Asm->getConstraintString(),
-                            Asm->hasSideEffects(), Asm->isAlignStack(),
-                            Asm->getDialect());
-  }
-};
-
-template<class ValType, class ValRefType, class TypeClass, class ConstantClass,
-         bool HasLargeKey = false /*true for arrays and structs*/ >
-class ConstantUniqueMap {
+template <class ConstantClass> class ConstantUniqueMap {
 public:
-  typedef std::pair<TypeClass*, ValType> MapKey;
-  typedef std::map<MapKey, ConstantClass *> MapTy;
-  typedef std::map<ConstantClass *, typename MapTy::iterator> InverseMapTy;
+  typedef typename ConstantInfo<ConstantClass>::ValType ValType;
+  typedef typename ConstantInfo<ConstantClass>::TypeClass TypeClass;
+  typedef std::pair<TypeClass *, ValType> LookupKey;
+
+private:
+  struct MapInfo {
+    typedef DenseMapInfo<ConstantClass *> ConstantClassInfo;
+    static inline ConstantClass *getEmptyKey() {
+      return ConstantClassInfo::getEmptyKey();
+    }
+    static inline ConstantClass *getTombstoneKey() {
+      return ConstantClassInfo::getTombstoneKey();
+    }
+    static unsigned getHashValue(const ConstantClass *CP) {
+      SmallVector<Constant *, 8> Storage;
+      return getHashValue(LookupKey(CP->getType(), ValType(CP, Storage)));
+    }
+    static bool isEqual(const ConstantClass *LHS, const ConstantClass *RHS) {
+      return LHS == RHS;
+    }
+    static unsigned getHashValue(const LookupKey &Val) {
+      return hash_combine(Val.first, Val.second.getHash());
+    }
+    static bool isEqual(const LookupKey &LHS, const ConstantClass *RHS) {
+      if (RHS == getEmptyKey() || RHS == getTombstoneKey())
+        return false;
+      if (LHS.first != RHS->getType())
+        return false;
+      return LHS.second == RHS;
+    }
+  };
+
+public:
+  typedef DenseMap<ConstantClass *, char, MapInfo> MapTy;
+
 private:
-  /// Map - This is the main map from the element descriptor to the Constants.
-  /// This is the primary way we avoid creating two of the same shape
-  /// constant.
   MapTy Map;
-    
-  /// InverseMap - If "HasLargeKey" is true, this contains an inverse mapping
-  /// from the constants to their element in Map.  This is important for
-  /// removal of constants from the array, which would otherwise have to scan
-  /// through the map with very large keys.
-  InverseMapTy InverseMap;
 
 public:
   typename MapTy::iterator map_begin() { return Map.begin(); }
   typename MapTy::iterator map_end() { return Map.end(); }
 
   void freeConstants() {
-    for (typename MapTy::iterator I=Map.begin(), E=Map.end();
-         I != E; ++I) {
+    for (auto &I : Map)
       // Asserts that use_empty().
-      delete I->second;
-    }
-  }
-    
-  /// InsertOrGetItem - Return an iterator for the specified element.
-  /// If the element exists in the map, the returned iterator points to the
-  /// entry and Exists=true.  If not, the iterator points to the newly
-  /// inserted entry and returns Exists=false.  Newly inserted entries have
-  /// I->second == 0, and should be filled in.
-  typename MapTy::iterator InsertOrGetItem(std::pair<MapKey, ConstantClass *>
-                                 &InsertVal,
-                                 bool &Exists) {
-    std::pair<typename MapTy::iterator, bool> IP = Map.insert(InsertVal);
-    Exists = !IP.second;
-    return IP.first;
-  }
-    
-private:
-  typename MapTy::iterator FindExistingElement(ConstantClass *CP) {
-    if (HasLargeKey) {
-      typename InverseMapTy::iterator IMI = InverseMap.find(CP);
-      assert(IMI != InverseMap.end() && IMI->second != Map.end() &&
-             IMI->second->second == CP &&
-             "InverseMap corrupt!");
-      return IMI->second;
-    }
-      
-    typename MapTy::iterator I =
-      Map.find(MapKey(static_cast<TypeClass*>(CP->getType()),
-                      ConstantKeyData<ConstantClass>::getValType(CP)));
-    if (I == Map.end() || I->second != CP) {
-      // FIXME: This should not use a linear scan.  If this gets to be a
-      // performance problem, someone should look at this.
-      for (I = Map.begin(); I != Map.end() && I->second != CP; ++I)
-        /* empty */;
-    }
-    return I;
+      delete I.first;
   }
 
-  ConstantClass *Create(TypeClass *Ty, ValRefType V,
-                        typename MapTy::iterator I) {
-    ConstantClass* Result =
-      ConstantCreator<ConstantClass,TypeClass,ValType>::create(Ty, V);
+private:
+  ConstantClass *create(TypeClass *Ty, ValType V) {
+    ConstantClass *Result = V.create(Ty);
 
     assert(Result->getType() == Ty && "Type specified is not correct!");
-    I = Map.insert(I, std::make_pair(MapKey(Ty, V), Result));
-
-    if (HasLargeKey)  // Remember the reverse mapping if needed.
-      InverseMap.insert(std::make_pair(Result, I));
+    insert(Result);
 
     return Result;
   }
+
 public:
-    
-  /// getOrCreate - Return the specified constant from the map, creating it if
-  /// necessary.
-  ConstantClass *getOrCreate(TypeClass *Ty, ValRefType V) {
-    MapKey Lookup(Ty, V);
-    ConstantClass* Result = nullptr;
-    
-    typename MapTy::iterator I = Map.find(Lookup);
-    // Is it in the map?  
-    if (I != Map.end())
-      Result = I->second;
-        
-    if (!Result) {
-      // If no preexisting value, create one now...
-      Result = Create(Ty, V, I);
-    }
-        
+  /// Return the specified constant from the map, creating it if necessary.
+  ConstantClass *getOrCreate(TypeClass *Ty, ValType V) {
+    LookupKey Lookup(Ty, V);
+    ConstantClass *Result = nullptr;
+
+    auto I = find(Lookup);
+    if (I == Map.end())
+      Result = create(Ty, V);
+    else
+      Result = I->first;
+    assert(Result && "Unexpected nullptr");
+
     return Result;
   }
 
+  /// Find the constant by lookup key.
+  typename MapTy::iterator find(LookupKey Lookup) {
+    return Map.find_as(Lookup);
+  }
+
+  /// Insert the constant into its proper slot.
+  void insert(ConstantClass *CP) { Map[CP] = '\0'; }
+
+  /// Remove this constant from the map
   void remove(ConstantClass *CP) {
-    typename MapTy::iterator I = FindExistingElement(CP);
+    typename MapTy::iterator I = Map.find(CP);
     assert(I != Map.end() && "Constant not found in constant table!");
-    assert(I->second == CP && "Didn't find correct element?");
-
-    if (HasLargeKey)  // Remember the reverse mapping if needed.
-      InverseMap.erase(CP);
-
+    assert(I->first == CP && "Didn't find correct element?");
     Map.erase(I);
   }
 
-  /// MoveConstantToNewSlot - If we are about to change C to be the element
-  /// specified by I, update our internal data structures to reflect this
-  /// fact.
-  void MoveConstantToNewSlot(ConstantClass *C, typename MapTy::iterator I) {
-    // First, remove the old location of the specified constant in the map.
-    typename MapTy::iterator OldI = FindExistingElement(C);
-    assert(OldI != Map.end() && "Constant not found in constant table!");
-    assert(OldI->second == C && "Didn't find correct element?");
-      
-     // Remove the old entry from the map.
-    Map.erase(OldI);
-    
-    // Update the inverse map so that we know that this constant is now
-    // located at descriptor I.
-    if (HasLargeKey) {
-      assert(I->second == C && "Bad inversemap entry!");
-      InverseMap[C] = I;
-    }
-  }
-
-  void dump() const {
-    DEBUG(dbgs() << "Constant.cpp: ConstantUniqueMap\n");
-  }
+  void dump() const { DEBUG(dbgs() << "Constant.cpp: ConstantUniqueMap\n"); }
 };
 
 // Unique map for aggregate constants
diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 4c2791f0a8d5..6513965ae7ad 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -75,7 +75,7 @@ LLVMContextImpl::~LLVMContextImpl() {
   // Free the constants.  This is important to do here to ensure that they are
   // freed before the LeakDetector is torn down.
   std::for_each(ExprConstants.map_begin(), ExprConstants.map_end(),
-                DropReferences());
+                DropFirst());
   std::for_each(ArrayConstants.map_begin(), ArrayConstants.map_end(),
                 DropFirst());
   std::for_each(StructConstants.map_begin(), StructConstants.map_end(),
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 1eead4ad41d5..b6a6254ba6a5 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -289,11 +289,9 @@ public:
 
   DenseMap<std::pair<const Function *, const BasicBlock *>, BlockAddress *>
     BlockAddresses;
-  ConstantUniqueMap<ExprMapKeyType, const ExprMapKeyType&, Type, ConstantExpr>
-    ExprConstants;
+  ConstantUniqueMap<ConstantExpr> ExprConstants;
 
-  ConstantUniqueMap<InlineAsmKeyType, const InlineAsmKeyType&, PointerType,
-                    InlineAsm> InlineAsms;
+  ConstantUniqueMap<InlineAsm> InlineAsms;
   
   ConstantInt *TheTrueVal;
   ConstantInt *TheFalseVal;