--- a/doc/build.py
+++ b/doc/build.py
@@ -4,53 +4,9 @@
 from __future__ import print_function
 import errno, os, shutil, sys, tempfile
 from subprocess import check_call, check_output, CalledProcessError, Popen, PIPE
-from distutils.version import LooseVersion
-
-def pip_install(package, commit=None, **kwargs):
-  "Install package using pip."
-  if commit:
-    check_version = kwargs.get('check_version', '')
-    #output = check_output(['pip', 'show', package.split('/')[1]])
-    #if check_version in output:
-    #  print('{} already installed'.format(package))
-    #  return
-    package = 'git+git://github.com/{0}.git@{1}'.format(package, commit)
-  print('Installing {}'.format(package))
-  check_call(['pip', 'install', package])
 
 def build_docs(version='dev'):
-  # Create virtualenv.
   doc_dir = os.path.dirname(os.path.realpath(__file__))
-  virtualenv_dir = 'virtualenv'
-  check_call(['virtualenv', virtualenv_dir])
-  import sysconfig
-  scripts_dir = os.path.basename(sysconfig.get_path('scripts'))
-  activate_this_file = os.path.join(virtualenv_dir, scripts_dir,
-                                    'activate_this.py')
-  with open(activate_this_file) as f:
-    exec(f.read(), dict(__file__=activate_this_file))
-  # Upgrade pip because installation of sphinx with pip 1.1 available on Travis
-  # is broken (see #207) and it doesn't support the show command.
-  from pkg_resources import get_distribution, DistributionNotFound
-  pip_version = get_distribution('pip').version
-  if LooseVersion(pip_version) < LooseVersion('1.5.4'):
-    print("Updating pip")
-    check_call(['pip', 'install', '--upgrade', 'pip'])
-  # Upgrade distribute because installation of sphinx with distribute 0.6.24
-  # available on Travis is broken (see #207).
-  try:
-    distribute_version = get_distribution('distribute').version
-    if LooseVersion(distribute_version) <= LooseVersion('0.6.24'):
-      print("Updating distribute")
-      check_call(['pip', 'install', '--upgrade', 'distribute'])
-  except DistributionNotFound:
-    pass
-  # Install Sphinx and Breathe.
-  pip_install('sphinx-doc/sphinx',
-              '12b83372ac9316e8cbe86e7fed889296a4cc29ee',
-              check_version='1.4.1.dev20160525')
-  pip_install('michaeljones/breathe',
-              '1c9d7f80378a92cffa755084823a78bb38ee4acc')
   # Build docs.
   cmd = ['doxygen', '-']
   p = Popen(cmd, stdin=PIPE)