Index: include/clang/AST/Expr.h
===================================================================
--- include/clang/AST/Expr.h
+++ include/clang/AST/Expr.h
@@ -29,6 +29,7 @@
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/AtomicOrdering.h"
 #include "llvm/Support/Compiler.h"
 
 namespace clang {
@@ -4830,16 +4831,6 @@
     BI_First = 0
   };
 
-  // The ABI values for various atomic memory orderings.
-  enum AtomicOrderingKind {
-    AO_ABI_memory_order_relaxed = 0,
-    AO_ABI_memory_order_consume = 1,
-    AO_ABI_memory_order_acquire = 2,
-    AO_ABI_memory_order_release = 3,
-    AO_ABI_memory_order_acq_rel = 4,
-    AO_ABI_memory_order_seq_cst = 5
-  };
-
 private:
   enum { PTR, ORDER, VAL1, ORDER_FAIL, VAL2, WEAK, END_EXPR };
   Stmt* SubExprs[END_EXPR];
Index: lib/CodeGen/CGAtomic.cpp
===================================================================
--- lib/CodeGen/CGAtomic.cpp
+++ lib/CodeGen/CGAtomic.cpp
@@ -243,11 +243,6 @@
     /// Materialize an atomic r-value in atomic-layout memory.
     Address materializeRValue(RValue rvalue) const;
 
-    /// \brief Translates LLVM atomic ordering to GNU atomic ordering for
-    /// libcalls.
-    static AtomicExpr::AtomicOrderingKind
-    translateAtomicOrdering(const llvm::AtomicOrdering AO);
-
     /// \brief Creates temp alloca for intermediate operations on atomic value.
     Address CreateTempAlloca() const;
   private:
@@ -292,25 +287,6 @@
   };
 }
 
-AtomicExpr::AtomicOrderingKind
-AtomicInfo::translateAtomicOrdering(const llvm::AtomicOrdering AO) {
-  switch (AO) {
-  case llvm::AtomicOrdering::Unordered:
-  case llvm::AtomicOrdering::NotAtomic:
-  case llvm::AtomicOrdering::Monotonic:
-    return AtomicExpr::AO_ABI_memory_order_relaxed;
-  case llvm::AtomicOrdering::Acquire:
-    return AtomicExpr::AO_ABI_memory_order_acquire;
-  case llvm::AtomicOrdering::Release:
-    return AtomicExpr::AO_ABI_memory_order_release;
-  case llvm::AtomicOrdering::AcquireRelease:
-    return AtomicExpr::AO_ABI_memory_order_acq_rel;
-  case llvm::AtomicOrdering::SequentiallyConsistent:
-    return AtomicExpr::AO_ABI_memory_order_seq_cst;
-  }
-  llvm_unreachable("Unhandled AtomicOrdering");
-}
-
 Address AtomicInfo::CreateTempAlloca() const {
   Address TempAlloca = CGF.CreateMemTemp(
       (LVal.isBitField() && ValueSizeInBits > AtomicSizeInBits) ? ValueTy
@@ -439,11 +415,11 @@
     default:
       FailureOrder = llvm::AtomicOrdering::Monotonic;
       break;
-    case AtomicExpr::AO_ABI_memory_order_consume:
-    case AtomicExpr::AO_ABI_memory_order_acquire:
+    case (int)llvm::AtomicOrderingCABI::consume:
+    case (int)llvm::AtomicOrderingCABI::acquire:
       FailureOrder = llvm::AtomicOrdering::Acquire;
       break;
-    case AtomicExpr::AO_ABI_memory_order_seq_cst:
+    case (int)llvm::AtomicOrderingCABI::seq_cst:
       FailureOrder = llvm::AtomicOrdering::SequentiallyConsistent;
       break;
     }
@@ -451,10 +427,10 @@
       // Don't assert on undefined behavior "failure argument shall be no
       // stronger than the success argument".
       FailureOrder =
-        llvm::AtomicCmpXchgInst::getStrongestFailureOrdering(SuccessOrder);
+          llvm::AtomicCmpXchgInst::getStrongestFailureOrdering(SuccessOrder);
     }
-    emitAtomicCmpXchg(CGF, E, IsWeak, Dest, Ptr, Val1, Val2, Size,
-                      SuccessOrder, FailureOrder);
+    emitAtomicCmpXchg(CGF, E, IsWeak, Dest, Ptr, Val1, Val2, Size, SuccessOrder,
+                      FailureOrder);
     return;
   }
 
@@ -487,9 +463,9 @@
     emitAtomicCmpXchg(CGF, E, IsWeak, Dest, Ptr, Val1, Val2,
                       Size, SuccessOrder, llvm::AtomicOrdering::Acquire);
     CGF.Builder.CreateBr(ContBB);
-    SI->addCase(CGF.Builder.getInt32(AtomicExpr::AO_ABI_memory_order_consume),
+    SI->addCase(CGF.Builder.getInt32((int)llvm::AtomicOrderingCABI::consume),
                 AcquireBB);
-    SI->addCase(CGF.Builder.getInt32(AtomicExpr::AO_ABI_memory_order_acquire),
+    SI->addCase(CGF.Builder.getInt32((int)llvm::AtomicOrderingCABI::acquire),
                 AcquireBB);
   }
   if (SeqCstBB) {
@@ -497,7 +473,7 @@
     emitAtomicCmpXchg(CGF, E, IsWeak, Dest, Ptr, Val1, Val2, Size, SuccessOrder,
                       llvm::AtomicOrdering::SequentiallyConsistent);
     CGF.Builder.CreateBr(ContBB);
-    SI->addCase(CGF.Builder.getInt32(AtomicExpr::AO_ABI_memory_order_seq_cst),
+    SI->addCase(CGF.Builder.getInt32((int)llvm::AtomicOrderingCABI::seq_cst),
                 SeqCstBB);
   }
 
@@ -1046,30 +1022,30 @@
   if (isa<llvm::ConstantInt>(Order)) {
     int ord = cast<llvm::ConstantInt>(Order)->getZExtValue();
     switch (ord) {
-    case AtomicExpr::AO_ABI_memory_order_relaxed:
+      case (int)llvm::AtomicOrderingCABI::relaxed:
       EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                    Size, llvm::AtomicOrdering::Monotonic);
       break;
-    case AtomicExpr::AO_ABI_memory_order_consume:
-    case AtomicExpr::AO_ABI_memory_order_acquire:
+    case (int)llvm::AtomicOrderingCABI::consume:
+    case (int)llvm::AtomicOrderingCABI::acquire:
       if (IsStore)
         break; // Avoid crashing on code with undefined behavior
       EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                    Size, llvm::AtomicOrdering::Acquire);
       break;
-    case AtomicExpr::AO_ABI_memory_order_release:
+    case (int)llvm::AtomicOrderingCABI::release:
       if (IsLoad)
         break; // Avoid crashing on code with undefined behavior
       EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                    Size, llvm::AtomicOrdering::Release);
       break;
-    case AtomicExpr::AO_ABI_memory_order_acq_rel:
+    case (int)llvm::AtomicOrderingCABI::acq_rel:
       if (IsLoad || IsStore)
         break; // Avoid crashing on code with undefined behavior
       EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                    Size, llvm::AtomicOrdering::AcquireRelease);
       break;
-    case AtomicExpr::AO_ABI_memory_order_seq_cst:
+    case (int)llvm::AtomicOrderingCABI::seq_cst:
       EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                    Size, llvm::AtomicOrdering::SequentiallyConsistent);
       break;
@@ -1119,9 +1095,9 @@
     EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                  Size, llvm::AtomicOrdering::Acquire);
     Builder.CreateBr(ContBB);
-    SI->addCase(Builder.getInt32(AtomicExpr::AO_ABI_memory_order_consume),
+    SI->addCase(Builder.getInt32((int)llvm::AtomicOrderingCABI::consume),
                 AcquireBB);
-    SI->addCase(Builder.getInt32(AtomicExpr::AO_ABI_memory_order_acquire),
+    SI->addCase(Builder.getInt32((int)llvm::AtomicOrderingCABI::acquire),
                 AcquireBB);
   }
   if (!IsLoad) {
@@ -1129,7 +1105,7 @@
     EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                  Size, llvm::AtomicOrdering::Release);
     Builder.CreateBr(ContBB);
-    SI->addCase(Builder.getInt32(AtomicExpr::AO_ABI_memory_order_release),
+    SI->addCase(Builder.getInt32((int)llvm::AtomicOrderingCABI::release),
                 ReleaseBB);
   }
   if (!IsLoad && !IsStore) {
@@ -1137,14 +1113,14 @@
     EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                  Size, llvm::AtomicOrdering::AcquireRelease);
     Builder.CreateBr(ContBB);
-    SI->addCase(Builder.getInt32(AtomicExpr::AO_ABI_memory_order_acq_rel),
+    SI->addCase(Builder.getInt32((int)llvm::AtomicOrderingCABI::acq_rel),
                 AcqRelBB);
   }
   Builder.SetInsertPoint(SeqCstBB);
   EmitAtomicOp(*this, E, Dest, Ptr, Val1, Val2, IsWeak, OrderFail,
                Size, llvm::AtomicOrdering::SequentiallyConsistent);
   Builder.CreateBr(ContBB);
-  SI->addCase(Builder.getInt32(AtomicExpr::AO_ABI_memory_order_seq_cst),
+  SI->addCase(Builder.getInt32((int)llvm::AtomicOrderingCABI::seq_cst),
               SeqCstBB);
 
   // Cleanup and return
@@ -1264,9 +1240,9 @@
            CGF.getContext().VoidPtrTy);
   Args.add(RValue::get(CGF.EmitCastToVoidPtr(AddForLoaded)),
            CGF.getContext().VoidPtrTy);
-  Args.add(RValue::get(
-               llvm::ConstantInt::get(CGF.IntTy, translateAtomicOrdering(AO))),
-           CGF.getContext().IntTy);
+  Args.add(
+      RValue::get(llvm::ConstantInt::get(CGF.IntTy, (int)llvm::toCABI(AO))),
+      CGF.getContext().IntTy);
   emitAtomicLibcall(CGF, "__atomic_load", CGF.getContext().VoidTy, Args);
 }
 
@@ -1482,11 +1458,11 @@
            CGF.getContext().VoidPtrTy);
   Args.add(RValue::get(CGF.EmitCastToVoidPtr(DesiredAddr)),
            CGF.getContext().VoidPtrTy);
-  Args.add(RValue::get(llvm::ConstantInt::get(
-               CGF.IntTy, translateAtomicOrdering(Success))),
+  Args.add(RValue::get(
+               llvm::ConstantInt::get(CGF.IntTy, (int)llvm::toCABI(Success))),
            CGF.getContext().IntTy);
-  Args.add(RValue::get(llvm::ConstantInt::get(
-               CGF.IntTy, translateAtomicOrdering(Failure))),
+  Args.add(RValue::get(
+               llvm::ConstantInt::get(CGF.IntTy, (int)llvm::toCABI(Failure))),
            CGF.getContext().IntTy);
   auto SuccessFailureRVal = emitAtomicLibcall(CGF, "__atomic_compare_exchange",
                                               CGF.getContext().BoolTy, Args);
@@ -1793,9 +1769,9 @@
                getContext().VoidPtrTy);
       args.add(RValue::get(EmitCastToVoidPtr(srcAddr.getPointer())),
                getContext().VoidPtrTy);
-      args.add(RValue::get(llvm::ConstantInt::get(
-                   IntTy, AtomicInfo::translateAtomicOrdering(AO))),
-               getContext().IntTy);
+      args.add(
+          RValue::get(llvm::ConstantInt::get(IntTy, (int)llvm::toCABI(AO))),
+          getContext().IntTy);
       emitAtomicLibcall(*this, "__atomic_store", getContext().VoidTy, args);
       return;
     }
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -1791,10 +1791,11 @@
 }
 
 static bool isValidOrderingForOp(int64_t Ordering, AtomicExpr::AtomicOp Op) {
-  if (Ordering < AtomicExpr::AO_ABI_memory_order_relaxed ||
-      Ordering > AtomicExpr::AO_ABI_memory_order_seq_cst)
+  if (Ordering < (int64_t)llvm::AtomicOrderingCABI::relaxed ||
+      Ordering > (int64_t)llvm::AtomicOrderingCABI::seq_cst)
     return false;
 
+  auto OrderingCABI = (llvm::AtomicOrderingCABI)Ordering;
   switch (Op) {
   case AtomicExpr::AO__c11_atomic_init:
     llvm_unreachable("There is no ordering argument for an init");
@@ -1802,15 +1803,15 @@
   case AtomicExpr::AO__c11_atomic_load:
   case AtomicExpr::AO__atomic_load_n:
   case AtomicExpr::AO__atomic_load:
-    return Ordering != AtomicExpr::AO_ABI_memory_order_release &&
-           Ordering != AtomicExpr::AO_ABI_memory_order_acq_rel;
+    return OrderingCABI != llvm::AtomicOrderingCABI::release &&
+           OrderingCABI != llvm::AtomicOrderingCABI::acq_rel;
 
   case AtomicExpr::AO__c11_atomic_store:
   case AtomicExpr::AO__atomic_store:
   case AtomicExpr::AO__atomic_store_n:
-    return Ordering != AtomicExpr::AO_ABI_memory_order_consume &&
-           Ordering != AtomicExpr::AO_ABI_memory_order_acquire &&
-           Ordering != AtomicExpr::AO_ABI_memory_order_acq_rel;
+    return OrderingCABI != llvm::AtomicOrderingCABI::consume &&
+           OrderingCABI != llvm::AtomicOrderingCABI::acquire &&
+           OrderingCABI != llvm::AtomicOrderingCABI::acq_rel;
 
   default:
     return true;