diff --git a/lib/VMCore/LLVMContextImpl.h b/lib/VMCore/LLVMContextImpl.h
index a27afc08b9f..9aba73781c4 100644
--- a/lib/VMCore/LLVMContextImpl.h
+++ b/lib/VMCore/LLVMContextImpl.h
@@ -29,6 +29,7 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Hashing.h"
 #include <vector>
 
 namespace llvm {
@@ -89,6 +90,107 @@ struct DenseMapAPFloatKeyInfo {
   }
 };
 
+struct AnonStructTypeKeyInfo {
+  struct KeyTy {
+    ArrayRef<Type*> ETypes;
+    bool isPacked;
+    KeyTy(const ArrayRef<Type*>& E, bool P) :
+      ETypes(E), isPacked(P) {}
+    KeyTy(const KeyTy& that) :
+      ETypes(that.ETypes), isPacked(that.isPacked) {}
+    KeyTy(const StructType* ST) :
+      ETypes(ArrayRef<Type*>(ST->element_begin(), ST->element_end())),
+      isPacked(ST->isPacked()) {}
+    bool operator==(const KeyTy& that) const {
+      if (isPacked != that.isPacked)
+        return false;
+      if (ETypes != that.ETypes)
+        return false;
+      return true;
+    }
+    bool operator!=(const KeyTy& that) const {
+      return !this->operator==(that);
+    }
+  };
+  static inline StructType* getEmptyKey() {
+    return DenseMapInfo<StructType*>::getEmptyKey();
+  }
+  static inline StructType* getTombstoneKey() {
+    return DenseMapInfo<StructType*>::getTombstoneKey();
+  }
+  static unsigned getHashValue(const KeyTy& Key) {
+    GeneralHash Hash;
+    Hash.add(Key.ETypes);
+    Hash.add(Key.isPacked);
+    return Hash.finish();
+  }
+  static unsigned getHashValue(const StructType *ST) {
+    return getHashValue(KeyTy(ST));
+  }
+  static bool isEqual(const KeyTy& LHS, const StructType *RHS) {
+    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
+      return false;
+    return LHS == KeyTy(RHS);
+  }
+  static bool isEqual(const StructType *LHS, const StructType *RHS) {
+    return LHS == RHS;
+  }
+};
+
+struct FunctionTypeKeyInfo {
+  struct KeyTy {
+    const Type *ReturnType;
+    ArrayRef<Type*> Params;
+    bool isVarArg;
+    KeyTy(const Type* R, const ArrayRef<Type*>& P, bool V) :
+      ReturnType(R), Params(P), isVarArg(V) {}
+    KeyTy(const KeyTy& that) :
+      ReturnType(that.ReturnType),
+      Params(that.Params),
+      isVarArg(that.isVarArg) {}
+    KeyTy(const FunctionType* FT) :
+      ReturnType(FT->getReturnType()),
+      Params(ArrayRef<Type*>(FT->param_begin(), FT->param_end())),
+      isVarArg(FT->isVarArg()) {}
+    bool operator==(const KeyTy& that) const {
+      if (ReturnType != that.ReturnType)
+        return false;
+      if (isVarArg != that.isVarArg)
+        return false;
+      if (Params != that.Params)
+        return false;
+      return true;
+    }
+    bool operator!=(const KeyTy& that) const {
+      return !this->operator==(that);
+    }
+  };
+  static inline FunctionType* getEmptyKey() {
+    return DenseMapInfo<FunctionType*>::getEmptyKey();
+  }
+  static inline FunctionType* getTombstoneKey() {
+    return DenseMapInfo<FunctionType*>::getTombstoneKey();
+  }
+  static unsigned getHashValue(const KeyTy& Key) {
+    GeneralHash Hash;
+    Hash.add(Key.ReturnType);
+    Hash.add(Key.Params);
+    Hash.add(Key.isVarArg);
+    return Hash.finish();
+  }
+  static unsigned getHashValue(const FunctionType *FT) {
+    return getHashValue(KeyTy(FT));
+  }
+  static bool isEqual(const KeyTy& LHS, const FunctionType *RHS) {
+    if (RHS == getEmptyKey() || RHS == getTombstoneKey())
+      return false;
+    return LHS == KeyTy(RHS);
+  }
+  static bool isEqual(const FunctionType *LHS, const FunctionType *RHS) {
+    return LHS == RHS;
+  }
+};
+
 /// DebugRecVH - This is a CallbackVH used to keep the Scope -> index maps
 /// up to date as MDNodes mutate.  This class is implemented in DebugLoc.cpp.
 class DebugRecVH : public CallbackVH {
@@ -180,9 +282,10 @@ public:
   
   DenseMap<unsigned, IntegerType*> IntegerTypes;
   
-  // TODO: Optimize FunctionTypes/AnonStructTypes!
-  std::map<std::vector<Type*>, FunctionType*> FunctionTypes;
-  std::map<std::vector<Type*>, StructType*> AnonStructTypes;
+  typedef DenseMap<FunctionType*, bool, FunctionTypeKeyInfo> FunctionTypeMap;
+  FunctionTypeMap FunctionTypes;
+  typedef DenseMap<StructType*, bool, AnonStructTypeKeyInfo> StructTypeMap;
+  StructTypeMap AnonStructTypes;
   StringMap<StructType*> NamedStructTypes;
   unsigned NamedStructTypesUniqueID;
     
diff --git a/lib/VMCore/Type.cpp b/lib/VMCore/Type.cpp
index 5cdddb36ee3..0bc4f74af21 100644
--- a/lib/VMCore/Type.cpp
+++ b/lib/VMCore/Type.cpp
@@ -390,24 +390,20 @@ FunctionType::FunctionType(Type *Result, ArrayRef<Type*> Params,
 // FunctionType::get - The factory function for the FunctionType class.
 FunctionType *FunctionType::get(Type *ReturnType,
                                 ArrayRef<Type*> Params, bool isVarArg) {
-  // TODO: This is brutally slow.
-  unsigned ParamsSize = Params.size();
-  std::vector<Type*> Key;
-  Key.reserve(ParamsSize + 2);
-  Key.push_back(const_cast<Type*>(ReturnType));
-  for (unsigned i = 0, e = ParamsSize; i != e; ++i)
-    Key.push_back(const_cast<Type*>(Params[i]));
-  if (isVarArg)
-    Key.push_back(0);
-  
   LLVMContextImpl *pImpl = ReturnType->getContext().pImpl;
-  FunctionType *&FT = pImpl->FunctionTypes[Key];
-  
-  if (FT == 0) {
+  FunctionTypeKeyInfo::KeyTy Key(ReturnType, Params, isVarArg);
+  LLVMContextImpl::FunctionTypeMap::iterator I =
+    pImpl->FunctionTypes.find_as(Key);
+  FunctionType *FT;
+
+  if (I == pImpl->FunctionTypes.end()) {
     FT = (FunctionType*) pImpl->TypeAllocator.
-      Allocate(sizeof(FunctionType) + sizeof(Type*) * (ParamsSize + 1),
+      Allocate(sizeof(FunctionType) + sizeof(Type*) * (Params.size() + 1),
                AlignOf<FunctionType>::Alignment);
     new (FT) FunctionType(ReturnType, Params, isVarArg);
+    pImpl->FunctionTypes[FT] = true;
+  } else {
+    FT = I->first;
   }
 
   return FT;
@@ -440,24 +436,22 @@ bool FunctionType::isValidArgumentType(Type *ArgTy) {
 
 StructType *StructType::get(LLVMContext &Context, ArrayRef<Type*> ETypes, 
                             bool isPacked) {
-  // FIXME: std::vector is horribly inefficient for this probe.
-  unsigned ETypesSize = ETypes.size();
-  std::vector<Type*> Key(ETypesSize);
-  for (unsigned i = 0, e = ETypesSize; i != e; ++i) {
-    assert(isValidElementType(ETypes[i]) &&
-           "Invalid type for structure element!");
-    Key[i] = ETypes[i];
+  LLVMContextImpl *pImpl = Context.pImpl;
+  AnonStructTypeKeyInfo::KeyTy Key(ETypes, isPacked);
+  LLVMContextImpl::StructTypeMap::iterator I =
+    pImpl->AnonStructTypes.find_as(Key);
+  StructType *ST;
+
+  if (I == pImpl->AnonStructTypes.end()) {
+    // Value not found.  Create a new type!
+    ST = new (Context.pImpl->TypeAllocator) StructType(Context);
+    ST->setSubclassData(SCDB_IsLiteral);  // Literal struct.
+    ST->setBody(ETypes, isPacked);
+    Context.pImpl->AnonStructTypes[ST] = true;
+  } else {
+    ST = I->first;
   }
-  if (isPacked)
-    Key.push_back(0);
-  
-  StructType *&ST = Context.pImpl->AnonStructTypes[Key];
-  if (ST) return ST;
-  
-  // Value not found.  Create a new type!
-  ST = new (Context.pImpl->TypeAllocator) StructType(Context);
-  ST->setSubclassData(SCDB_IsLiteral);  // Literal struct.
-  ST->setBody(ETypes, isPacked);
+
   return ST;
 }