Index: cfe/trunk/include/clang/Basic/BuiltinsAArch64.def
===================================================================
--- cfe/trunk/include/clang/Basic/BuiltinsAArch64.def
+++ cfe/trunk/include/clang/Basic/BuiltinsAArch64.def
@@ -45,4 +45,9 @@
 BUILTIN(__builtin_arm_crc32d, "UiUiLUi", "nc")
 BUILTIN(__builtin_arm_crc32cd, "UiUiLUi", "nc")
 
+// Memory barrier
+BUILTIN(__builtin_arm_dmb, "vUi", "nc")
+BUILTIN(__builtin_arm_dsb, "vUi", "nc")
+BUILTIN(__builtin_arm_isb, "vUi", "nc")
+
 #undef BUILTIN
Index: cfe/trunk/lib/Sema/SemaChecking.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp
+++ cfe/trunk/lib/Sema/SemaChecking.cpp
@@ -645,7 +645,18 @@
   if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
     return true;
 
-  return false;
+  // For intrinsics which take an immediate value as part of the instruction,
+  // range check them here.
+  unsigned i = 0, l = 0, u = 0;
+  switch (BuiltinID) {
+  default: return false;
+  case AArch64::BI__builtin_arm_dmb:
+  case AArch64::BI__builtin_arm_dsb:
+  case AArch64::BI__builtin_arm_isb: l = 0; u = 15; break;
+  }
+
+  // FIXME: VFP Intrinsics should error if VFP not present.
+  return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
 }
 
 bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
Index: cfe/trunk/test/CodeGen/builtins-arm64.c
===================================================================
--- cfe/trunk/test/CodeGen/builtins-arm64.c
+++ cfe/trunk/test/CodeGen/builtins-arm64.c
@@ -23,3 +23,9 @@
   __builtin_arm_sev();    //CHECK: call {{.*}} @llvm.aarch64.hint(i32 4)
   __builtin_arm_sevl();   //CHECK: call {{.*}} @llvm.aarch64.hint(i32 5)
 }
+
+void barriers() {
+  __builtin_arm_dmb(1);  //CHECK: call {{.*}} @llvm.aarch64.dmb(i32 1)
+  __builtin_arm_dsb(2);  //CHECK: call {{.*}} @llvm.aarch64.dsb(i32 2)
+  __builtin_arm_isb(3);  //CHECK: call {{.*}} @llvm.aarch64.isb(i32 3)
+}
Index: cfe/trunk/test/Sema/builtins-arm64.c
===================================================================
--- cfe/trunk/test/Sema/builtins-arm64.c
+++ cfe/trunk/test/Sema/builtins-arm64.c
@@ -16,3 +16,9 @@
 void test_clear_cache_no_args() {
   __clear_cache(); // expected-error {{too few arguments to function call}}
 }
+
+void test_memory_barriers() {
+  __builtin_arm_dmb(16); // expected-error {{argument should be a value from 0 to 15}}
+  __builtin_arm_dsb(17); // expected-error {{argument should be a value from 0 to 15}}
+  __builtin_arm_isb(18); // expected-error {{argument should be a value from 0 to 15}}
+}