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diff --git a/llvm/lib/Transforms/ObjCARC/ARCInstKind.h b/llvm/lib/Transforms/ObjCARC/ARCInstKind.h
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+++ b/llvm/lib/Transforms/ObjCARC/ARCInstKind.h
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+//===--- ARCInstKind.h - ARC instruction equivalence classes -*- C++ -*----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_ARCINSTKIND_H
+#define LLVM_LIB_TRANSFORMS_OBJCARC_ARCINSTKIND_H
+
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Function.h"
+
+namespace llvm {
+namespace objcarc {
+
+/// \enum ARCInstKind
+///
+/// \brief Equivalence classes of instructions in the ARC Model.
+///
+/// Since we do not have "instructions" to represent ARC concepts in LLVM IR,
+/// we instead operate on equivalence classes of instructions.
+///
+/// TODO: This should be split into two enums: a runtime entry point enum
+/// (possibly united with the ARCRuntimeEntrypoint class) and an enum that deals
+/// with effects of instructions in the ARC model (which would handle the notion
+/// of a User or CallOrUser).
+enum class ARCInstKind {
+  Retain,                   ///< objc_retain
+  RetainRV,                 ///< objc_retainAutoreleasedReturnValue
+  RetainBlock,              ///< objc_retainBlock
+  Release,                  ///< objc_release
+  Autorelease,              ///< objc_autorelease
+  AutoreleaseRV,            ///< objc_autoreleaseReturnValue
+  AutoreleasepoolPush,      ///< objc_autoreleasePoolPush
+  AutoreleasepoolPop,       ///< objc_autoreleasePoolPop
+  NoopCast,                 ///< objc_retainedObject, etc.
+  FusedRetainAutorelease,   ///< objc_retainAutorelease
+  FusedRetainAutoreleaseRV, ///< objc_retainAutoreleaseReturnValue
+  LoadWeakRetained,         ///< objc_loadWeakRetained (primitive)
+  StoreWeak,                ///< objc_storeWeak (primitive)
+  InitWeak,                 ///< objc_initWeak (derived)
+  LoadWeak,                 ///< objc_loadWeak (derived)
+  MoveWeak,                 ///< objc_moveWeak (derived)
+  CopyWeak,                 ///< objc_copyWeak (derived)
+  DestroyWeak,              ///< objc_destroyWeak (derived)
+  StoreStrong,              ///< objc_storeStrong (derived)
+  IntrinsicUser,            ///< clang.arc.use
+  CallOrUser,               ///< could call objc_release and/or "use" pointers
+  Call,                     ///< could call objc_release
+  User,                     ///< could "use" a pointer
+  None                      ///< anything else
+};
+
+raw_ostream &operator<<(raw_ostream &OS, const ARCInstKind Class);
+
+/// \brief Test if the given class is a kind of user.
+inline static bool IsUser(ARCInstKind Class) {
+  return Class == ARCInstKind::User || Class == ARCInstKind::CallOrUser ||
+         Class == ARCInstKind::IntrinsicUser;
+}
+
+/// \brief Test if the given class is objc_retain or equivalent.
+static inline bool IsRetain(ARCInstKind Class) {
+  return Class == ARCInstKind::Retain || Class == ARCInstKind::RetainRV;
+}
+
+/// \brief Test if the given class is objc_autorelease or equivalent.
+static inline bool IsAutorelease(ARCInstKind Class) {
+  return Class == ARCInstKind::Autorelease ||
+         Class == ARCInstKind::AutoreleaseRV;
+}
+
+/// \brief Test if the given class represents instructions which return their
+/// argument verbatim.
+static inline bool IsForwarding(ARCInstKind Class) {
+  return Class == ARCInstKind::Retain || Class == ARCInstKind::RetainRV ||
+         Class == ARCInstKind::Autorelease ||
+         Class == ARCInstKind::AutoreleaseRV || Class == ARCInstKind::NoopCast;
+}
+
+/// \brief Test if the given class represents instructions which do nothing if
+/// passed a null pointer.
+static inline bool IsNoopOnNull(ARCInstKind Class) {
+  return Class == ARCInstKind::Retain || Class == ARCInstKind::RetainRV ||
+         Class == ARCInstKind::Release || Class == ARCInstKind::Autorelease ||
+         Class == ARCInstKind::AutoreleaseRV ||
+         Class == ARCInstKind::RetainBlock;
+}
+
+/// \brief Test if the given class represents instructions which are always safe
+/// to mark with the "tail" keyword.
+static inline bool IsAlwaysTail(ARCInstKind Class) {
+  // ARCInstKind::RetainBlock may be given a stack argument.
+  return Class == ARCInstKind::Retain || Class == ARCInstKind::RetainRV ||
+         Class == ARCInstKind::AutoreleaseRV;
+}
+
+/// \brief Test if the given class represents instructions which are never safe
+/// to mark with the "tail" keyword.
+static inline bool IsNeverTail(ARCInstKind Class) {
+  /// It is never safe to tail call objc_autorelease since by tail calling
+  /// objc_autorelease, we also tail call -[NSObject autorelease] which supports
+  /// fast autoreleasing causing our object to be potentially reclaimed from the
+  /// autorelease pool which violates the semantics of __autoreleasing types in
+  /// ARC.
+  return Class == ARCInstKind::Autorelease;
+}
+
+/// \brief Test if the given class represents instructions which are always safe
+/// to mark with the nounwind attribute.
+static inline bool IsNoThrow(ARCInstKind Class) {
+  // objc_retainBlock is not nounwind because it calls user copy constructors
+  // which could theoretically throw.
+  return Class == ARCInstKind::Retain || Class == ARCInstKind::RetainRV ||
+         Class == ARCInstKind::Release || Class == ARCInstKind::Autorelease ||
+         Class == ARCInstKind::AutoreleaseRV ||
+         Class == ARCInstKind::AutoreleasepoolPush ||
+         Class == ARCInstKind::AutoreleasepoolPop;
+}
+
+/// Test whether the given instruction can autorelease any pointer or cause an
+/// autoreleasepool pop.
+static inline bool CanInterruptRV(ARCInstKind Class) {
+  switch (Class) {
+  case ARCInstKind::AutoreleasepoolPop:
+  case ARCInstKind::CallOrUser:
+  case ARCInstKind::Call:
+  case ARCInstKind::Autorelease:
+  case ARCInstKind::AutoreleaseRV:
+  case ARCInstKind::FusedRetainAutorelease:
+  case ARCInstKind::FusedRetainAutoreleaseRV:
+    return true;
+  default:
+    return false;
+  }
+}
+
+/// \brief Determine if F is one of the special known Functions.  If it isn't,
+/// return ARCInstKind::CallOrUser.
+ARCInstKind GetFunctionClass(const Function *F);
+
+/// \brief Determine which objc runtime call instruction class V belongs to.
+///
+/// This is similar to GetARCInstKind except that it only detects objc
+/// runtime calls. This allows it to be faster.
+///
+static inline ARCInstKind GetBasicARCInstKind(const Value *V) {
+  if (const CallInst *CI = dyn_cast<CallInst>(V)) {
+    if (const Function *F = CI->getCalledFunction())
+      return GetFunctionClass(F);
+    // Otherwise, be conservative.
+    return ARCInstKind::CallOrUser;
+  }
+
+  // Otherwise, be conservative.
+  return isa<InvokeInst>(V) ? ARCInstKind::CallOrUser : ARCInstKind::User;
+}
+
+/// \brief Determine what kind of construct V is.
+ARCInstKind GetARCInstKind(const Value *V);
+
+} // end namespace objcarc
+} // end namespace llvm
+
+#endif