diff --git a/include/llvm/Intrinsics.td b/include/llvm/Intrinsics.td
index ef4f0961ed5..6b6b0f51d13 100644
--- a/include/llvm/Intrinsics.td
+++ b/include/llvm/Intrinsics.td
@@ -153,8 +153,12 @@ def int_stacksave     : Intrinsic<[llvm_ptr_ty], [IntrReadMem]>,
                         GCCBuiltin<"__builtin_stack_save">;
 def int_stackrestore  : Intrinsic<[llvm_void_ty, llvm_ptr_ty]>,
                         GCCBuiltin<"__builtin_stack_restore">;
+// IntrWriteArgMem is more pessimistic than strictly necessary for prefetch,
+// however it does conveniently prevent the prefetch from being reordered
+// with respect to nearby accesses to the same memory.
 def int_prefetch      : Intrinsic<[llvm_void_ty, llvm_ptr_ty, 
-                                   llvm_i32_ty, llvm_i32_ty]>;
+                                   llvm_i32_ty, llvm_i32_ty],
+                                  [IntrWriteArgMem]>;
 def int_pcmarker      : Intrinsic<[llvm_void_ty, llvm_i32_ty]>;
 
 def int_readcyclecounter : Intrinsic<[llvm_i64_ty]>;