diff --git a/tools/docs/mach_commands.py b/tools/docs/mach_commands.py
index afd7f3ead54..825e5ec38aa 100644
--- a/tools/docs/mach_commands.py
+++ b/tools/docs/mach_commands.py
@@ -2,16 +2,19 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, # You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from __future__ import absolute_import, unicode_literals
+from __future__ import absolute_import, print_function, unicode_literals
 
 import os
+import sys
 
 from mach.decorators import (
+    Command,
     CommandArgument,
     CommandProvider,
-    Command,
 )
 
+import mozhttpd
+
 from mozbuild.base import MachCommandBase
 
 
@@ -21,15 +24,17 @@ class Documentation(MachCommandBase):
 
     @Command('doc', category='devenv',
         description='Generate and display documentation from the tree.')
-    @CommandArgument('what', default=None, nargs='*',
+    @CommandArgument('what', nargs='*', metavar='DIRECTORY [, DIRECTORY]',
         help='Path(s) to documentation to build and display.')
     @CommandArgument('--format', default='html',
         help='Documentation format to write.')
-    @CommandArgument('--outdir', default=None,
+    @CommandArgument('--outdir', default=None, metavar='DESTINATION',
         help='Where to write output.')
     @CommandArgument('--no-open', dest='auto_open', default=True, action='store_false',
-        help='Don\'t automatically open HTML docs in a browser.')
-    def build_docs(self, what=None, format=None, outdir=None, auto_open=True):
+        help="Don't automatically open HTML docs in a browser.")
+    @CommandArgument('--http', const=':6666', metavar='ADDRESS', nargs='?',
+        help='Serve documentation on an HTTP server, e.g. ":6666".')
+    def build_docs(self, what=None, format=None, outdir=None, auto_open=True, http=None):
         self._activate_virtualenv()
         self.virtualenv_manager.install_pip_package('sphinx_rtd_theme==0.1.6')
 
@@ -38,9 +43,9 @@ class Documentation(MachCommandBase):
 
         if not outdir:
             outdir = os.path.join(self.topobjdir, 'docs')
-
         if not what:
             what = [os.path.join(self.topsrcdir, 'tools')]
+        outdir = os.path.join(outdir, format)
 
         generated = []
         failed = []
@@ -54,7 +59,7 @@ class Documentation(MachCommandBase):
 
             # find project name to use as a namespace within `outdir`
             project = self._find_project_name(docdir)
-            savedir = os.path.join(outdir, format, project)
+            savedir = os.path.join(outdir, project)
 
             args = [
                 'sphinx',
@@ -68,18 +73,26 @@ class Documentation(MachCommandBase):
             else:
                 generated.append(savedir)
 
-            # attempt to open html docs in a browser
             index_path = os.path.join(savedir, 'index.html')
-            if auto_open and os.path.isfile(index_path):
+            if not http and auto_open and os.path.isfile(index_path):
                 webbrowser.open(index_path)
 
         if generated:
-            print("\nGenerated documentation:\n%s\n" % '\n'.join(generated))
+            print('\nGenerated documentation:\n%s\n' % '\n'.join(generated))
 
         if failed:
-            failed = ['%s - %s' % (f[0], f[1]) for f in failed]
-            print("ERROR failed to generate documentation:\n%s" % '\n'.join(failed))
-            return 1
+            failed = ['%s: %s' % (f[0], f[1]) for f in failed]
+            return die('failed to generate documentation:\n%s' % '\n'.join(failed))
+
+        if http is not None:
+            host, port = http.split(':', 1)
+            addr = (host, int(port))
+            if len(addr) != 2:
+                return die('invalid address: %s' % http)
+
+            httpd = mozhttpd.MozHttpd(host=addr[0], port=addr[1], docroot=outdir)
+            print('listening on %s:%d' % addr)
+            httpd.start(block=True)
 
     def _find_project_name(self, path):
         import imp
@@ -96,3 +109,9 @@ class Documentation(MachCommandBase):
             p = os.path.join(path, d)
             if os.path.isfile(os.path.join(p, 'conf.py')):
                 return p
+
+
+def die(msg, exit_code=1):
+    msg = '%s: %s' % (sys.argv[0], msg)
+    print(msg, file=sys.stderr)
+    return exit_code