diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 32bf6e0..41c7613 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -309,6 +309,10 @@
         if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
           return ExprError();
         break;
+      case llvm::Triple::arm64:
+        if (CheckARM64BuiltinFunctionCall(BuiltinID, TheCall))
+          return ExprError();
+        break;
       case llvm::Triple::aarch64:
       case llvm::Triple::aarch64_be:
         if (CheckAArch64BuiltinFunctionCall(BuiltinID, TheCall))
@@ -369,7 +373,7 @@
 /// the vector type specified by the NeonTypeFlags.  This is used to check
 /// the pointer arguments for Neon load/store intrinsics.
 static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context,
-                               bool IsAArch64) {
+                               bool IsPolyUnsigned, bool IsInt64Long) {
   switch (Flags.getEltType()) {
   case NeonTypeFlags::Int8:
     return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
@@ -378,15 +382,15 @@
   case NeonTypeFlags::Int32:
     return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
   case NeonTypeFlags::Int64:
-    if (IsAArch64)
+    if (IsInt64Long)
       return Flags.isUnsigned() ? Context.UnsignedLongTy : Context.LongTy;
     else
       return Flags.isUnsigned() ? Context.UnsignedLongLongTy
                                 : Context.LongLongTy;
   case NeonTypeFlags::Poly8:
-    return IsAArch64 ? Context.UnsignedCharTy : Context.SignedCharTy;
+    return IsPolyUnsigned ? Context.UnsignedCharTy : Context.SignedCharTy;
   case NeonTypeFlags::Poly16:
-    return IsAArch64 ? Context.UnsignedShortTy : Context.ShortTy;
+    return IsPolyUnsigned ? Context.UnsignedShortTy : Context.ShortTy;
   case NeonTypeFlags::Poly64:
     return Context.UnsignedLongTy;
   case NeonTypeFlags::Poly128:
@@ -434,9 +438,13 @@
     ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
     QualType RHSTy = RHS.get()->getType();
 
-    bool IsAArch64 =
-        Context.getTargetInfo().getTriple().getArch() == llvm::Triple::aarch64;
-    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context, IsAArch64);
+    llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
+    bool IsPolyUnsigned =
+        Arch == llvm::Triple::aarch64 || Arch == llvm::Triple::arm64;
+    bool IsInt64Long =
+        Context.getTargetInfo().getInt64Type() == TargetInfo::SignedLong;
+    QualType EltTy =
+        getNeonEltType(NeonTypeFlags(TV), Context, IsPolyUnsigned, IsInt64Long);
     if (HasConstPtr)
       EltTy = EltTy.withConst();
     QualType LHSTy = Context.getPointerType(EltTy);
@@ -487,11 +495,15 @@
   return false;
 }
 
-bool Sema::CheckARMBuiltinExclusiveCall(unsigned BuiltinID, CallExpr *TheCall) {
+bool Sema::CheckARMBuiltinExclusiveCall(unsigned BuiltinID, CallExpr *TheCall,
+                                        unsigned MaxWidth) {
   assert((BuiltinID == ARM::BI__builtin_arm_ldrex ||
-          BuiltinID == ARM::BI__builtin_arm_strex) &&
+          BuiltinID == ARM::BI__builtin_arm_strex ||
+          BuiltinID == ARM64::BI__builtin_arm_ldrex ||
+          BuiltinID == ARM64::BI__builtin_arm_strex) &&
          "unexpected ARM builtin");
-  bool IsLdrex = BuiltinID == ARM::BI__builtin_arm_ldrex;
+  bool IsLdrex = BuiltinID == ARM::BI__builtin_arm_ldrex ||
+                 BuiltinID == ARM64::BI__builtin_arm_ldrex;
 
   DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
 
@@ -552,7 +564,8 @@
   }
 
   // But ARM doesn't have instructions to deal with 128-bit versions.
-  if (Context.getTypeSize(ValType) > 64) {
+  if (Context.getTypeSize(ValType) > MaxWidth) {
+    assert(MaxWidth == 64 && "Diagnostic unexpectedly inaccurate");
     Diag(DRE->getLocStart(), diag::err_atomic_exclusive_builtin_pointer_size)
       << PointerArg->getType() << PointerArg->getSourceRange();
     return true;
@@ -598,7 +611,7 @@
 
   if (BuiltinID == ARM::BI__builtin_arm_ldrex ||
       BuiltinID == ARM::BI__builtin_arm_strex) {
-    return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall);
+    return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 64);
   }
 
   if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
@@ -636,6 +649,21 @@
   return false;
 }
 
+bool Sema::CheckARM64BuiltinFunctionCall(unsigned BuiltinID,
+                                         CallExpr *TheCall) {
+  llvm::APSInt Result;
+
+  if (BuiltinID == ARM64::BI__builtin_arm_ldrex ||
+      BuiltinID == ARM64::BI__builtin_arm_strex) {
+    return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 128);
+  }
+
+  if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
+    return true;
+
+  return false;
+}
+
 bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   unsigned i = 0, l = 0, u = 0;
   switch (BuiltinID) {