diff --git a/build/file_utils.py b/build/file_utils.py
new file mode 100644
index 0000000..1559a9b
--- /dev/null
+++ b/build/file_utils.py
@@ -0,0 +1,49 @@
+# Copyright 2018 - The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""File-related utilities."""
+
+
+import os
+import shutil
+import tempfile
+
+
+def make_parent_dirs(file_path):
+    """Creates parent directories for the file_path."""
+    if os.path.exists(file_path):
+        return
+
+    parent_dir = os.path.dirname(file_path)
+    if parent_dir and not os.path.exists(parent_dir):
+        os.makedirs(parent_dir)
+
+
+def filter_out(pattern_files, input_file):
+    """"Removes lines in input_file that match any line in pattern_files."""
+
+    # Prepares patterns.
+    patterns = []
+    for f in pattern_files:
+        patterns.extend(open(f).readlines())
+
+    # Copy lines that are not in the pattern.
+    tmp_output = tempfile.NamedTemporaryFile()
+    with open(input_file, 'r') as in_file:
+        tmp_output.writelines(line for line in in_file.readlines()
+                              if line not in patterns)
+        tmp_output.flush()
+
+    # Replaces the input_file.
+    shutil.copyfile(tmp_output.name, input_file)