--- a/devtools/moz.build
+++ b/devtools/moz.build
@@ -1,28 +1,35 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # 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/.
 
-if CONFIG['MOZ_DEVTOOLS'] and CONFIG['MOZ_DEVTOOLS'] not in ('all', 'server'):
+if CONFIG['MOZ_DEVTOOLS'] and CONFIG['MOZ_DEVTOOLS'] not in ('all', 'server', 'addon'):
     error('Unsupported MOZ_DEVTOOLS value: %s' % (CONFIG['MOZ_DEVTOOLS']))
 
 if CONFIG['MOZ_DEVTOOLS'] == 'all':
     DIRS += [
         'client',
     ]
 
+# `addon` is a special build mode to strip everything except binary components
+# and shim modules that are going to stay in Firefox once DevTools ship as an
+# add-on.
 DIRS += [
-    'server',
-    'shared',
     'shim',
 ]
 
+if CONFIG['MOZ_DEVTOOLS'] != 'addon':
+    DIRS += [
+        'server',
+        'shared',
+    ]
+
 # /browser uses DIST_SUBDIR.  We opt-in to this treatment when building
 # DevTools for the browser to keep the root omni.ja slim for use by external XUL
 # apps.  Mulet also uses this since it includes /browser.
 if CONFIG['MOZ_BUILD_APP'] == 'browser':
     DIST_SUBDIR = 'browser'
     export('DIST_SUBDIR')
 
 with Files('**'):