diff --git a/commit_queue.py b/commit_queue.py
index b08d4fe..25ddb38 100755
--- a/commit_queue.py
+++ b/commit_queue.py
@@ -26,6 +26,7 @@
 sys.path.insert(0, THIRD_PARTY_DIR)
 
 from cq_client import cq_pb2
+from cq_client import validate_config
 from protobuf26 import text_format
 
 def usage(more):
@@ -143,6 +144,25 @@
 
 CMDbuilders.func_usage_more = '<path-to-cq-config>'
 
+
+def CMDvalidate(parser, args):
+  """Validates a CQ config.
+
+  Takes a single argument - path to the CQ config to be validated. Returns 0 on
+  valid config, non-zero on invalid config. Errors and warnings are printed to
+  screen.
+  """
+  _, args = parser.parse_args(args)
+  if len(args) != 1:
+    parser.error('Expected a single path to CQ config. Got: %s' %
+                 ' '.join(args))
+
+  with open(args[0]) as config_file:
+    cq_config = config_file.read()
+  return 0 if validate_config.IsValid(cq_config) else 1
+
+CMDvalidate.func_usage_more = '<path-to-cq-config>'
+
 ###############################################################################
 ## Boilerplate code
 
diff --git a/third_party/cq_client/README.md b/third_party/cq_client/README.md
new file mode 100644
index 0000000..d37caa6
--- /dev/null
+++ b/third_party/cq_client/README.md
@@ -0,0 +1,17 @@
+This directory contains CQ client library to be distributed to other repos. If
+you need to modify some files in this directory, please make sure that you are
+changing the canonical version of the source code and not one of the copies,
+which should only be updated as a whole using Glyco (when available, see
+http://crbug.com/489420).
+
+The canonical version is located at `https://chrome-internal.googlesource.com/
+infra/infra_internal/+/master/commit_queue/cq_client`.
+
+To generate `cq_pb2.py`, please use protoc version 2.6.1:
+
+    cd commit_queue/cq_client
+    protoc cq.proto --python_out $(pwd)
+
+Additionally, please make sure to use proto3-compatible syntax, e.g. no default
+values, no required fields. Ideally, we should use proto3 generator already,
+however alpha version thereof is still unstable.
diff --git a/third_party/cq_client/test/cq_example.cfg b/third_party/cq_client/test/cq_example.cfg
new file mode 100644
index 0000000..dc69acf
--- /dev/null
+++ b/third_party/cq_client/test/cq_example.cfg
@@ -0,0 +1,55 @@
+version: 1
+cq_name: "infra"
+cq_status_url: "https://chromium-cq-status.appspot.com"
+hide_ref_in_committed_msg: true
+commit_burst_delay: 600
+max_commit_burst: 10
+in_production: false
+git_repo_url: "http://github.com/infra/infra.git"
+target_ref: "refs/pending/heads/master"
+
+rietveld {
+  url: "https://codereview.chromium.org"
+  project_bases: "https://chromium.googlesource.com/infra/infra.git@master"
+}
+
+verifiers {
+  reviewer_lgtm: {
+     committer_list: "chromium"
+     max_wait_secs: 600
+     no_lgtm_msg: "LGTM is missing"
+  }
+
+  tree_status: {
+     tree_status_url: "https://infra-status.appspot.com"
+  }
+
+  try_job {
+    buckets {
+      name: "tryserver.blink"
+      builders { name: "android_blink_compile_dbg" }
+      builders { name: "android_blink_compile_rel" }
+      builders {
+        name: "win_blink_rel"
+        triggered: true
+      }
+    }
+    buckets {
+      name: "tryserver.chromium.linux"
+      builders {
+        name: "android_arm64_dbg_recipe"
+      }
+      builders {
+        name: "linux_chromium_rel_ng"
+        experiment_percentage: 0.1
+      }
+    }
+    buckets {
+      name: "tryserver.chromium.mac"
+      builders {
+        name: "ios_dbg_simulator_ninja"
+        experiment_percentage: 1.0
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/third_party/cq_client/test/validate_config_test.py b/third_party/cq_client/test/validate_config_test.py
new file mode 100755
index 0000000..d7c0971
--- /dev/null
+++ b/third_party/cq_client/test/validate_config_test.py
@@ -0,0 +1,52 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for tools/validate_config.py."""
+
+import mock
+import os
+import unittest
+
+from cq_client import cq_pb2
+from cq_client import validate_config
+
+
+TEST_DIR = os.path.dirname(os.path.abspath(__file__))
+
+
+class TestValidateConfig(unittest.TestCase):
+  def test_is_valid(self):
+    with open(os.path.join(TEST_DIR, 'cq_example.cfg'), 'r') as test_config:
+      self.assertTrue(validate_config.IsValid(test_config.read()))
+
+  def test_has_field(self):
+    config = cq_pb2.Config()
+
+    self.assertFalse(validate_config._HasField(config, 'version'))
+    config.version = 1
+    self.assertTrue(validate_config._HasField(config, 'version'))
+
+    self.assertFalse(validate_config._HasField(
+        config, 'rietveld.project_bases'))
+    config.rietveld.project_bases.append('foo://bar')
+    self.assertTrue(validate_config._HasField(
+        config, 'rietveld.project_bases'))
+
+    self.assertFalse(validate_config._HasField(
+        config, 'verifiers.try_job.buckets'))
+    self.assertFalse(validate_config._HasField(
+        config, 'verifiers.try_job.buckets.name'))
+
+    bucket = config.verifiers.try_job.buckets.add()
+    bucket.name = 'tryserver.chromium.linux'
+
+
+    self.assertTrue(validate_config._HasField(
+        config, 'verifiers.try_job.buckets'))
+    self.assertTrue(validate_config._HasField(
+        config, 'verifiers.try_job.buckets.name'))
+
+    config.verifiers.try_job.buckets.add()
+    self.assertFalse(validate_config._HasField(
+        config, 'verifiers.try_job.buckets.name'))
diff --git a/third_party/cq_client/validate_config.py b/third_party/cq_client/validate_config.py
new file mode 100644
index 0000000..1e34b86
--- /dev/null
+++ b/third_party/cq_client/validate_config.py
@@ -0,0 +1,112 @@
+#!/usr/bin/env python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""CQ config validation library."""
+
+import argparse
+# The 'from google import protobuf' below was replaced to fix an issue where
+# some users may have built-in google package installed on their system, which
+# is incompatible with cq_pb2 below. This hack can be removed after
+# http://crbug.com/503067 is resolved.
+import protobuf26 as protobuf
+import logging
+import re
+import sys
+
+from cq_client import cq_pb2
+
+
+REQUIRED_FIELDS = [
+  'version',
+  'rietveld',
+  'rietveld.url',
+  'verifiers',
+  'cq_name',
+]
+
+LEGACY_FIELDS = [
+  'svn_repo_url',
+  'server_hooks_missing',
+  'verifiers_with_patch',
+]
+
+EMAIL_REGEXP = '^[^@]+@[^@]+\.[^@]+$'
+
+
+def _HasField(message, field_path):
+  """Checks that at least one field with given path exist in the proto message.
+
+  This function correctly handles repeated fields and will make sure that each
+  repeated field will have required sub-path, e.g. if 'abc' is a repeated field
+  and field_path is 'abc.def', then the function will only return True when each
+  entry for 'abc' will contain at least one value for 'def'.
+
+  Args:
+    message (google.protobuf.message.Message): Protocol Buffer message to check.
+    field_path (string): Path to the target field separated with ".".
+
+  Return:
+    True if at least one such field is explicitly set in the message.
+  """
+  path_parts = field_path.split('.', 1)
+  field_name = path_parts[0]
+  sub_path = path_parts[1] if len(path_parts) == 2 else None
+
+  field_labels = {fd.name: fd.label for fd in message.DESCRIPTOR.fields}
+  repeated_field = (field_labels[field_name] ==
+                    protobuf.descriptor.FieldDescriptor.LABEL_REPEATED)
+
+  if sub_path:
+    field = getattr(message, field_name)
+    if repeated_field:
+      if not field:
+        return False
+      return all(_HasField(entry, sub_path) for entry in field)
+    else:
+      return _HasField(field, sub_path)
+  else:
+    if repeated_field:
+      return len(getattr(message, field_name)) > 0
+    else:
+      return message.HasField(field_name)
+
+
+def IsValid(cq_config):
+  """Validates a CQ config and prints errors/warnings to the screen.
+
+  Args:
+    cq_config (string): Unparsed text format of the CQ config proto.
+
+  Returns:
+    True if the config is valid.
+  """
+  try:
+    config = cq_pb2.Config()
+    protobuf.text_format.Merge(cq_config, config)
+  except protobuf.text_format.ParseError as e:
+    logging.error('Failed to parse config as protobuf:\n%s', e)
+    return False
+
+  for fname in REQUIRED_FIELDS:
+    if not _HasField(config, fname):
+      logging.error('%s is a required field', fname)
+      return False
+
+  for fname in LEGACY_FIELDS:
+    if _HasField(config, fname):
+      logging.warn('%s is a legacy field', fname)
+
+
+  for base in config.rietveld.project_bases:
+    try:
+      re.compile(base)
+    except re.error:
+      logging.error('failed to parse "%s" in project_bases as a regexp', base)
+      return False
+
+  # TODO(sergiyb): For each field, check valid values depending on its
+  # semantics, e.g. email addresses, regular expressions etc.
+
+  return True