diff --git a/include/llvm/IR/Function.h b/include/llvm/IR/Function.h
index 568b55c87b9..a7dea5ca3d7 100644
--- a/include/llvm/IR/Function.h
+++ b/include/llvm/IR/Function.h
@@ -113,6 +113,10 @@ private:
   Function(const Function&) LLVM_DELETED_FUNCTION;
   void operator=(const Function&) LLVM_DELETED_FUNCTION;
 
+  /// Do the actual lookup of an intrinsic ID when the query could not be
+  /// answered from the cache.
+  unsigned lookupIntrinsicID() const LLVM_READONLY;
+
   /// Function ctor - If the (optional) Module argument is specified, the
   /// function is automatically inserted into the end of the function list for
   /// the module.
@@ -141,10 +145,12 @@ public:
 
   /// getIntrinsicID - This method returns the ID number of the specified
   /// function, or Intrinsic::not_intrinsic if the function is not an
-  /// instrinsic, or if the pointer is null.  This value is always defined to be
+  /// intrinsic, or if the pointer is null.  This value is always defined to be
   /// zero to allow easy checking for whether a function is intrinsic or not.
   /// The particular intrinsic functions which correspond to this value are
-  /// defined in llvm/Intrinsics.h.
+  /// defined in llvm/Intrinsics.h.  Results are cached in the LLVM context,
+  /// subsequent requests for the same ID return results much faster from the
+  /// cache.
   ///
   unsigned getIntrinsicID() const LLVM_READONLY;
   bool isIntrinsic() const { return getName().startswith("llvm."); }
diff --git a/lib/IR/Function.cpp b/lib/IR/Function.cpp
index 5c444d238ad..5559a6c56e6 100644
--- a/lib/IR/Function.cpp
+++ b/lib/IR/Function.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/Function.h"
+#include "LLVMContextImpl.h"
 #include "SymbolTableListTraitsImpl.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
@@ -208,6 +209,10 @@ Function::~Function() {
 
   // Remove the function from the on-the-side GC table.
   clearGC();
+
+  // Remove the intrinsicID from the Cache.
+  if(getValueName() && isIntrinsic())
+    getContext().pImpl->IntrinsicIDCache.erase(this);
 }
 
 void Function::BuildLazyArguments() const {
@@ -337,18 +342,35 @@ void Function::copyAttributesFrom(const GlobalValue *Src) {
 /// intrinsic, or if the pointer is null.  This value is always defined to be
 /// zero to allow easy checking for whether a function is intrinsic or not.  The
 /// particular intrinsic functions which correspond to this value are defined in
-/// llvm/Intrinsics.h.
+/// llvm/Intrinsics.h.  Results are cached in the LLVM context, subsequent
+/// requests for the same ID return results much faster from the cache.
 ///
 unsigned Function::getIntrinsicID() const {
   const ValueName *ValName = this->getValueName();
   if (!ValName || !isIntrinsic())
     return 0;
+
+  LLVMContextImpl::IntrinsicIDCacheTy &IntrinsicIDCache =
+    getContext().pImpl->IntrinsicIDCache;
+  if(!IntrinsicIDCache.count(this)) {
+    unsigned Id = lookupIntrinsicID();
+    IntrinsicIDCache[this]=Id;
+    return Id;
+  }
+  return IntrinsicIDCache[this];
+}
+
+/// This private method does the actual lookup of an intrinsic ID when the query
+/// could not be answered from the cache.
+unsigned Function::lookupIntrinsicID() const {
+  const ValueName *ValName = this->getValueName();
   unsigned Len = ValName->getKeyLength();
   const char *Name = ValName->getKeyData();
 
 #define GET_FUNCTION_RECOGNIZER
 #include "llvm/IR/Intrinsics.gen"
 #undef GET_FUNCTION_RECOGNIZER
+
   return 0;
 }
 
diff --git a/lib/IR/LLVMContextImpl.h b/lib/IR/LLVMContextImpl.h
index 7353dc03611..0c659b81b70 100644
--- a/lib/IR/LLVMContextImpl.h
+++ b/lib/IR/LLVMContextImpl.h
@@ -318,7 +318,7 @@ public:
 
   /// ValueHandles - This map keeps track of all of the value handles that are
   /// watching a Value*.  The Value::HasValueHandle bit is used to know
-  // whether or not a value has an entry in this map.
+  /// whether or not a value has an entry in this map.
   typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
   ValueHandlesTy ValueHandles;
   
@@ -350,6 +350,11 @@ public:
   /// to date.
   std::vector<std::pair<DebugRecVH, DebugRecVH> > ScopeInlinedAtRecords;
   
+  /// IntrinsicIDCache - Cache of intrinsic name (string) to numeric ID mappings
+  /// requested in this context
+  typedef DenseMap<const Function*, unsigned> IntrinsicIDCacheTy;
+  IntrinsicIDCacheTy IntrinsicIDCache;
+
   int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
   int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
   
diff --git a/lib/IR/Module.cpp b/lib/IR/Module.cpp
index 8affcc94696..0825bda53ba 100644
--- a/lib/IR/Module.cpp
+++ b/lib/IR/Module.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/IR/Module.h"
 #include "SymbolTableListTraitsImpl.h"
+#include "LLVMContextImpl.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
diff --git a/lib/IR/Value.cpp b/lib/IR/Value.cpp
index 5bdce2b5425..adc702e05e6 100644
--- a/lib/IR/Value.cpp
+++ b/lib/IR/Value.cpp
@@ -195,6 +195,9 @@ void Value::setName(const Twine &NewName) {
   if (getSymTab(this, ST))
     return;  // Cannot set a name on this value (e.g. constant).
 
+  if (Function *F = dyn_cast<Function>(this))
+    getContext().pImpl->IntrinsicIDCache.erase(F);
+
   if (!ST) { // No symbol table to update?  Just do the change.
     if (NameRef.empty()) {
       // Free the name for this value.
@@ -307,7 +310,7 @@ void Value::replaceAllUsesWith(Value *New) {
   // Notify all ValueHandles (if present) that this value is going away.
   if (HasValueHandle)
     ValueHandleBase::ValueIsRAUWd(this, New);
-  
+
   while (!use_empty()) {
     Use &U = *UseList;
     // Must handle Constants specially, we cannot call replaceUsesOfWith on a
@@ -318,10 +321,10 @@ void Value::replaceAllUsesWith(Value *New) {
         continue;
       }
     }
-    
+
     U.set(New);
   }
-  
+
   if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
     BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
 }