Add LLVM license header to MLIR BUILD files

PiperOrigin-RevId: 371826096
Change-Id: Ife6b5ffb72f0e63f1dfd006255086c2a0d1b415e
diff --git a/third_party/mlir/BUILD b/third_party/mlir/BUILD
index 376e95f..da8367e 100644
--- a/third_party/mlir/BUILD
+++ b/third_party/mlir/BUILD
@@ -1,3 +1,7 @@
+# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
 # Description:
 #   The MLIR "Multi-Level Intermediate Representation" Compiler Infrastructure
 
diff --git a/third_party/mlir/test.BUILD b/third_party/mlir/test.BUILD
index 8ad5127..06e20e4 100644
--- a/third_party/mlir/test.BUILD
+++ b/third_party/mlir/test.BUILD
@@ -1,3 +1,7 @@
+# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
 load("@org_tensorflow//third_party/mlir:tblgen.bzl", "gentbl", "td_library")
 
 package(