diff --git a/grpc.bzl b/grpc.bzl
index 5b5735e1bc4..9f2693126af 100644
--- a/grpc.bzl
+++ b/grpc.bzl
@@ -1,3 +1,39 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""
+Bazel macros to declare gRPC libraries automatically generated from proto files.
+
+This file declares two macros:
+- objc_proto_library
+- objc_grpc_library
+"""
 
 def _lower_underscore_to_upper_camel(str):
   humps = []
@@ -16,6 +52,9 @@ def _file_with_extension(src, ext):
   return "".join(elements[:-1] + [basename, ext])
 
 def _protoc_invocation(srcs, flags):
+  """Returns a command line to invoke protoc from a genrule, on the given
+  sources, using the given flags.
+  """
   protoc_command = "$(location //external:protoc) -I . "
   srcs_params = ""
   for src in srcs:
@@ -23,6 +62,9 @@ def _protoc_invocation(srcs, flags):
   return protoc_command + flags + srcs_params
 
 def objc_proto_library(name, srcs, visibility=None):
+  """Declares an objc_library for the code generated by protoc from the given
+  proto sources. This generated code doesn't include proto services.
+  """
   h_files = []
   m_files = []
   for src in srcs:
@@ -48,6 +90,10 @@ def objc_proto_library(name, srcs, visibility=None):
   )
 
 def objc_grpc_library(name, services, other_messages, visibility=None):
+  """Declares an objc_library for the code generated by gRPC and protoc from the
+  given proto sources (services and other_messages). The generated code doesn't
+  include proto services of the files passed as other_messages.
+  """
   objc_proto_library(name + "_messages", services + other_messages)
 
   h_files = []
@@ -57,7 +103,8 @@ def objc_grpc_library(name, services, other_messages, visibility=None):
     h_files += [_file_with_extension(src, ".pbrpc.h")]
     m_files += [_file_with_extension(src, ".pbrpc.m")]
 
-  protoc_flags = "--grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(location //external:grpc_protoc_plugin_objc)"
+  protoc_flags = ("--grpc_out=$(GENDIR) --plugin=" +
+      "protoc-gen-grpc=$(location //external:grpc_protoc_plugin_objc)")
 
   native.genrule(
     name = name + "_codegen",