diff --git a/generator/dawn_generator.gni b/generator/dawn_generator.gni
index 3ab81e7..fc72883 100644
--- a/generator/dawn_generator.gni
+++ b/generator/dawn_generator.gni
@@ -15,6 +15,16 @@
 import("../scripts/dawn_overrides_with_defaults.gni")
 import("generator_lib.gni")
 
+dawn_allowed_gen_output_dirs = [
+  "src/dawn/",
+  "src/dawn_native/",
+  "src/dawn_native/opengl/",
+  "src/dawn_wire/client/",
+  "src/dawn_wire/server/",
+  "src/dawn_wire/",
+  "src/include/dawn/",
+]
+
 # Template to help invoking Dawn code generators based on generator_lib
 #
 #   dawn_generator("my_target_gen") {
@@ -47,6 +57,7 @@
     forward_variables_from(invoker, "*")
     generator_lib_dir = "${dawn_root}/generator"
     jinja2_path = dawn_jinja2_dir
+    allowed_output_dirs = dawn_allowed_gen_output_dirs
   }
 }
 
diff --git a/generator/generator_lib.gni b/generator/generator_lib.gni
index d3698f2..10c560d 100644
--- a/generator/generator_lib.gni
+++ b/generator/generator_lib.gni
@@ -35,6 +35,11 @@
 #
 #   jinja2_path: Optional Jinja2 installation path.
 #
+#   allowed_output_dirs: Optional list of directories that are the only
+#     directories in which files of `outputs` are allowed to be (and not
+#     in children directories). Generation will fail if an output isn't
+#     in a directory in the list.
+#
 #   root_dir: Optional root source dir for Python dependencies
 #     computation. Defaults to "${generator_lib_dir}/..". Any dependency
 #     outside of this directory is considered a system file and will be
@@ -111,6 +116,19 @@
     rebase_path(_expected_outputs_file, root_build_dir),
   ]
 
+  # Check that all of the outputs are in a directory that's allowed. This is
+  # useful to keep the list of directories in sink with other parts of the
+  # build.
+  if (defined(invoker.allowed_output_dirs)) {
+    _allowed_output_dirs_file = "${_gen_dir}/${target_name}.allowed_output_dirs"
+    write_file(_allowed_output_dirs_file, invoker.allowed_output_dirs)
+
+    _generator_args += [
+      "--allowed-output-dirs-file",
+      rebase_path(_allowed_output_dirs_file, root_build_dir),
+    ]
+  }
+
   # The code generator invocation that will write the JSON tarball, check the
   # outputs are what's expected and write a depfile for Ninja.
   action(_json_tarball_target) {
diff --git a/generator/generator_lib.py b/generator/generator_lib.py
index 7307f56..9dcd179 100644
--- a/generator/generator_lib.py
+++ b/generator/generator_lib.py
@@ -211,6 +211,7 @@
     parser.add_argument('--depfile', default=None, type=str, help='Name of the Ninja depfile to create for the JSON tarball')
     parser.add_argument('--expected-outputs-file', default=None, type=str, help="File to compare outputs with and fail if it doesn't match")
     parser.add_argument('--root-dir', default=None, type=str, help='Optional source root directory for Python dependency computations')
+    parser.add_argument('--allowed-output-dirs-file', default=None, type=str, help="File containing a list of allowed directories where files can be output.")
 
     args = parser.parse_args()
 
@@ -231,6 +232,26 @@
 
     outputs = _do_renders(renders, args.template_dir)
 
+    # The caller wants to assert that the outputs are only in specific directories.
+    if args.allowed_output_dirs_file != None:
+        with open(args.allowed_output_dirs_file) as f:
+            allowed_dirs = set([line.strip() for line in f.readlines()])
+
+        for directory in allowed_dirs:
+            if not directory.endswith('/'):
+                print('Allowed directory entry "{}" doesn\'t end with /'.format(directory))
+                return 1
+
+        def check_in_subdirectory(path, directory):
+            return path.startswith(directory) and not '/' in path[len(directory):]
+
+        for render in renders:
+            if not any(check_in_subdirectory(render.output, directory) for directory in allowed_dirs):
+                print('Output file "{}" is not in the allowed directory list below:'.format(render.output))
+                for directory in sorted(allowed_dirs):
+                    print('    "{}"'.format(directory))
+                return 1
+
     # Output the tarball and its depfile
     if args.output_json_tarball != None:
         json_root = {}