--- a/accessible/jsat/moz.build
+++ b/accessible/jsat/moz.build
@@ -1,17 +1,15 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/accessibility'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.accessibility += [
     'AccessFu.jsm',
     'Constants.jsm',
     'ContentControl.jsm',
     'EventManager.jsm',
     'Gestures.jsm',
     'OutputGenerator.jsm',
     'PointerAdapter.jsm',
     'Presentation.jsm',

--- a/addon-sdk/moz.build
+++ b/addon-sdk/moz.build
@@ -3,13 +3,11 @@
 # 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
 DIRS += ["source/modules/system"]
 
-JS_MODULES_PATH = 'modules/sdk'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.sdk += [
     'source/app-extension/bootstrap.js',
 ]

--- a/addon-sdk/source/modules/system/moz.build
+++ b/addon-sdk/source/modules/system/moz.build
@@ -1,11 +1,9 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/sdk/system'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.sdk.system += [
     'XulApp.js',
 ]

--- a/browser/components/loop/moz.build
+++ b/browser/components/loop/moz.build
@@ -1,22 +1,20 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 JAR_MANIFESTS += ['jar.mn']
 
-JS_MODULES_PATH = 'modules/loop'
-
 XPCSHELL_TESTS_MANIFESTS += ['test/xpcshell/xpcshell.ini']
 
 BROWSER_CHROME_MANIFESTS += [
     'test/mochitest/browser.ini',
 ]
 
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.loop += [
     'MozLoopAPI.jsm',
     'MozLoopPushHandler.jsm',
     'MozLoopService.jsm',
     'MozLoopWorker.js',
 ]

--- a/browser/components/sessionstore/moz.build
+++ b/browser/components/sessionstore/moz.build
@@ -17,19 +17,17 @@ XPIDL_SOURCES += [
 XPIDL_MODULE = 'sessionstore'
 
 EXTRA_COMPONENTS += [
     'nsSessionStartup.js',
     'nsSessionStore.js',
     'nsSessionStore.manifest',
 ]
 
-JS_MODULES_PATH = 'modules/sessionstore'
-
-EXTRA_JS_MODULES = [
+EXTRA_JS_MODULES.sessionstore = [
     'ContentRestore.jsm',
     'DocShellCapabilities.jsm',
     'FrameTree.jsm',
     'GlobalState.jsm',
     'PageStyle.jsm',
     'PrivacyFilter.jsm',
     'PrivacyLevel.jsm',
     'RecentlyClosedTabsAndWindowsMenuUtils.jsm',
@@ -41,13 +39,13 @@ EXTRA_JS_MODULES = [
     'SessionWorker.js',
     'SessionWorker.jsm',
     'TabAttributes.jsm',
     'TabState.jsm',
     'TabStateCache.jsm',
     'Utils.jsm',
 ]
 
-EXTRA_PP_JS_MODULES += [
+EXTRA_PP_JS_MODULES.sessionstore += [
     'SessionSaver.jsm',
     'SessionStore.jsm',
 ]
 

--- a/browser/components/tabview/moz.build
+++ b/browser/components/tabview/moz.build
@@ -1,14 +1,12 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-EXTRA_JS_MODULES = ['modules/utils.jsm']
-JS_MODULES_PATH  = 'modules/tabview'
-
+EXTRA_JS_MODULES.tabview = ['modules/utils.jsm']
 BROWSER_CHROME_MANIFESTS += [
     'test/browser.ini',
 ]
 
 JAR_MANIFESTS += ['jar.mn']
\ No newline at end of file

--- a/browser/components/translation/moz.build
+++ b/browser/components/translation/moz.build
@@ -1,15 +1,13 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/translation'
-
-EXTRA_JS_MODULES = [
+EXTRA_JS_MODULES.translation = [
     'BingTranslator.jsm',
     'cld2/cld-worker.js',
     'cld2/cld-worker.js.mem',
     'LanguageDetector.jsm',
     'Translation.jsm',
     'TranslationContentHandler.jsm',
     'TranslationDocument.jsm'
 ]

--- a/browser/devtools/app-manager/moz.build
+++ b/browser/devtools/app-manager/moz.build
@@ -2,19 +2,17 @@
 # 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
 
-JS_MODULES_PATH = 'modules/devtools/app-manager'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools["app-manager"] += [
     'app-projects.js',
     'app-validator.js',
     'builtin-adb-store.js',
     'connection-store.js',
     'device-store.js',
     'simulators-store.js',
     'webapps-store.js',
 ]

--- a/browser/devtools/canvasdebugger/moz.build
+++ b/browser/devtools/canvasdebugger/moz.build
@@ -1,12 +1,10 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/canvasdebugger'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.canvasdebugger += [
     'panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/commandline/moz.build
+++ b/browser/devtools/commandline/moz.build
@@ -1,11 +1,9 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/commandline'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.commandline += [
     'commands-index.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/debugger/moz.build
+++ b/browser/devtools/debugger/moz.build
@@ -1,13 +1,11 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/debugger'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.debugger += [
     'debugger-commands.js',
     'panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/eyedropper/moz.build
+++ b/browser/devtools/eyedropper/moz.build
@@ -1,14 +1,12 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/eyedropper'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.eyedropper += [
     'commands.js',
     'eyedropper.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/inspector/moz.build
+++ b/browser/devtools/inspector/moz.build
@@ -1,14 +1,12 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/inspector'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.inspector += [
     'breadcrumbs.js',
     'inspector-commands.js',
     'inspector-panel.js',
     'selector-search.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/markupview/moz.build
+++ b/browser/devtools/markupview/moz.build
@@ -1,14 +1,12 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
-JS_MODULES_PATH = 'modules/devtools/markupview'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.markupview += [
     'html-editor.js',
     'markup-view.js',
 ]

--- a/browser/devtools/moz.build
+++ b/browser/devtools/moz.build
@@ -33,13 +33,11 @@ DIRS += [
 
 EXTRA_COMPONENTS += [
     'devtools-clhandler.js',
     'devtools-clhandler.manifest',
 ]
 
 JAR_MANIFESTS += ['jar.mn']
 
-JS_MODULES_PATH = 'modules/devtools'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools += [
     'main.js',
 ]

--- a/browser/devtools/netmonitor/moz.build
+++ b/browser/devtools/netmonitor/moz.build
@@ -1,12 +1,10 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/netmonitor'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.netmonitor += [
     'panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/profiler/moz.build
+++ b/browser/devtools/profiler/moz.build
@@ -1,18 +1,16 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
-JS_MODULES_PATH = 'modules/devtools/profiler'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.profiler += [
     'cleopatra.js',
     'commands.js',
     'consts.js',
     'controller.js',
     'panel.js',
     'sidebar.js',
 ]

--- a/browser/devtools/responsivedesign/moz.build
+++ b/browser/devtools/responsivedesign/moz.build
@@ -1,11 +1,9 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools += [
     'resize-commands.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/scratchpad/moz.build
+++ b/browser/devtools/scratchpad/moz.build
@@ -1,14 +1,12 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/scratchpad'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.scratchpad += [
     'scratchpad-commands.js',
     'scratchpad-panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/shadereditor/moz.build
+++ b/browser/devtools/shadereditor/moz.build
@@ -1,12 +1,10 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/shadereditor'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.shadereditor += [
     'panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/sourceeditor/moz.build
+++ b/browser/devtools/sourceeditor/moz.build
@@ -1,17 +1,15 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/sourceeditor'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.sourceeditor += [
     'autocomplete.js',
     'css-autocompleter.js',
     'css-tokenizer.js',
     'debugger.js',
     'editor.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/styleinspector/moz.build
+++ b/browser/devtools/styleinspector/moz.build
@@ -2,17 +2,15 @@
 # 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 XPCSHELL_TESTS_MANIFESTS += ['test/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools/styleinspector'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.styleinspector += [
     'computed-view.js',
     'css-parsing-utils.js',
     'rule-view.js',
     'style-inspector-overlays.js',
     'style-inspector.js',
 ]

--- a/browser/devtools/tilt/moz.build
+++ b/browser/devtools/tilt/moz.build
@@ -1,15 +1,13 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/tilt'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.tilt += [
     'tilt-commands.js',
     'tilt-gl.js',
     'tilt-math.js',
     'tilt-utils.js',
     'tilt-visualizer-style.js',
     'tilt-visualizer.js',
     'tilt.js',
     'TiltWorkerCrafter.js',

--- a/browser/devtools/webaudioeditor/moz.build
+++ b/browser/devtools/webaudioeditor/moz.build
@@ -1,12 +1,10 @@
 # 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/.
 
-JS_MODULES_PATH = 'modules/devtools/webaudioeditor'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.webaudioeditor += [
     'panel.js'
 ]
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']

--- a/browser/devtools/webconsole/moz.build
+++ b/browser/devtools/webconsole/moz.build
@@ -1,18 +1,16 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 
-JS_MODULES_PATH = 'modules/devtools/webconsole'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.webconsole += [
     'console-commands.js',
     'console-output.js',
     'hudservice.js',
     'network-panel.js',
     'panel.js',
     'webconsole.js',
 ]

--- a/browser/devtools/webide/moz.build
+++ b/browser/devtools/webide/moz.build
@@ -7,16 +7,14 @@
 DIRS += [
     'content',
     'components',
     'themes',
 ]
 
 MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
 
-JS_MODULES_PATH = 'modules/devtools/webide'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.webide += [
     'modules/addons.js',
     'modules/app-manager.js',
     'modules/remote-resources.js',
     'modules/runtimes.js'
 ]

--- a/browser/experiments/moz.build
+++ b/browser/experiments/moz.build
@@ -2,17 +2,15 @@
 # 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/.
 
 EXTRA_COMPONENTS += [
     'Experiments.manifest',
     'ExperimentsService.js',
 ]
 
-JS_MODULES_PATH = 'modules/experiments'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.experiments += [
   'Experiments.jsm',
 ]
 
 XPCSHELL_TESTS_MANIFESTS += ['test/xpcshell/xpcshell.ini']
 
 SPHINX_TREES['experiments'] = 'docs'

--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -41,19 +41,17 @@ UNIFIED_SOURCES += [
     'MediaManager.cpp',
 ]
 
 EXTRA_COMPONENTS += [
     'PeerConnection.js',
     'PeerConnection.manifest',
 ]
 
-JS_MODULES_PATH = 'modules/media'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.media += [
     'IdpProxy.jsm',
     'PeerConnectionIdp.jsm',
     'RTCStatsReport.jsm',
 ]
 
 if CONFIG['MOZ_B2G']:
     EXPORTS.mozilla += [
         'MediaPermissionGonk.h',

--- a/python/mozbuild/mozbuild/backend/recursivemake.py
+++ b/python/mozbuild/mozbuild/backend/recursivemake.py
@@ -946,18 +946,44 @@ class RecursiveMakeBackend(CommonBackend
             backend_file.write('FINAL_TARGET = $(DEPTH)/%s\n' % (obj.target))
         else:
             backend_file.write('FINAL_TARGET = $(if $(XPI_NAME),$(DIST)/xpi-stage/$(XPI_NAME),$(DIST)/bin)$(DIST_SUBDIR:%=/%)\n')
 
         if not obj.enabled:
             backend_file.write('NO_DIST_INSTALL := 1\n')
 
     def _process_javascript_modules(self, obj, backend_file):
-        if obj.flavor != 'testing':
-            raise Exception('We only support testing JavaScriptModules instances.')
+        if obj.flavor not in ('extra', 'extra_pp', 'testing'):
+            raise Exception('Unsupported JavaScriptModules instance: %s' % obj.flavor)
+
+        if obj.flavor == 'extra':
+            def onelement(element, namespace):
+                if not element.get_strings():
+                    return
+
+                prefix = 'extra_js_%s' % namespace.replace('/', '_')
+                backend_file.write('%s_FILES := %s\n'
+                                   % (prefix, ' '.join(element.get_strings())))
+                backend_file.write('%s_DEST = $(FINAL_TARGET)/%s\n' % (prefix, namespace))
+                backend_file.write('INSTALL_TARGETS += %s\n\n' % prefix)
+            self._process_hierarchy_elements(obj, obj.modules, 'modules', onelement)
+            return
+
+        if obj.flavor == 'extra_pp':
+            def onelement(element, namespace):
+                if not element.get_strings():
+                    return
+
+                prefix = 'extra_pp_js_%s' % namespace.replace('/', '_')
+                backend_file.write('%s := %s\n'
+                                   % (prefix, ' '.join(element.get_strings())))
+                backend_file.write('%s_PATH = $(FINAL_TARGET)/%s\n' % (prefix, namespace))
+                backend_file.write('PP_TARGETS += %s\n\n' % prefix)
+            self._process_hierarchy_elements(obj, obj.modules, 'modules', onelement)
+            return
 
         if not self.environment.substs.get('ENABLE_TESTS', False):
             return
 
         manifest = self._install_manifests['tests']
 
         def onmodule(source, dest, flags):
             manifest.add_symlink(source, mozpath.join('modules', dest))

--- a/python/mozbuild/mozbuild/frontend/emitter.py
+++ b/python/mozbuild/mozbuild/frontend/emitter.py
@@ -368,19 +368,17 @@ class TreeMetadataEmitter(LoggingMixin):
         varlist = [
             'ANDROID_GENERATED_RESFILES',
             'ANDROID_RES_DIRS',
             'DISABLE_STL_WRAPPING',
             'EXTRA_ASSEMBLER_FLAGS',
             'EXTRA_COMPILE_FLAGS',
             'EXTRA_COMPONENTS',
             'EXTRA_DSO_LDOPTS',
-            'EXTRA_JS_MODULES',
             'EXTRA_PP_COMPONENTS',
-            'EXTRA_PP_JS_MODULES',
             'FAIL_ON_WARNINGS',
             'FILES_PER_UNIFIED_FILE',
             'USE_STATIC_LIBS',
             'GENERATED_FILES',
             'IS_GYP_DIR',
             'JS_MODULES_PATH',
             'MSVC_ENABLE_PGO',
             'NO_DIST_INSTALL',
@@ -502,16 +500,24 @@ class TreeMetadataEmitter(LoggingMixin):
                         'because it is already used in %s' % (program, kind,
                         self._binaries[program].relativedir), sandbox)
                 self._binaries[program] = cls(sandbox, program,
                     is_unit_test=kind == 'CPP_UNIT_TESTS')
                 self._linkage.append((sandbox, self._binaries[program],
                     'HOST_USE_LIBS' if kind == 'HOST_SIMPLE_PROGRAMS'
                     else 'USE_LIBS'))
 
+        extra_js_modules = sandbox.get('EXTRA_JS_MODULES')
+        if extra_js_modules:
+            yield JavaScriptModules(sandbox, extra_js_modules, 'extra')
+
+        extra_pp_js_modules = sandbox.get('EXTRA_PP_JS_MODULES')
+        if extra_pp_js_modules:
+            yield JavaScriptModules(sandbox, extra_pp_js_modules, 'extra_pp')
+
         test_js_modules = sandbox.get('TESTING_JS_MODULES')
         if test_js_modules:
             yield JavaScriptModules(sandbox, test_js_modules, 'testing')
 
         simple_lists = [
             ('GENERATED_EVENTS_WEBIDL_FILES', GeneratedEventWebIDLFile),
             ('GENERATED_WEBIDL_FILES', GeneratedWebIDLFile),
             ('IPDL_SOURCES', IPDLFile),

--- a/python/mozbuild/mozbuild/frontend/sandbox_symbols.py
+++ b/python/mozbuild/mozbuild/frontend/sandbox_symbols.py
@@ -181,25 +181,25 @@ VARIABLES = {
 
     'EXTRA_COMPONENTS': (StrictOrderingOnAppendList, list,
         """Additional component files to distribute.
 
        This variable contains a list of files to copy into
        ``$(FINAL_TARGET)/components/``.
         """, 'libs'),
 
-    'EXTRA_JS_MODULES': (StrictOrderingOnAppendList, list,
+    'EXTRA_JS_MODULES': (HierarchicalStringList, list,
         """Additional JavaScript files to distribute.
 
         This variable contains a list of files to copy into
         ``$(FINAL_TARGET)/$(JS_MODULES_PATH)``. ``JS_MODULES_PATH`` defaults
         to ``modules`` if left undefined.
         """, 'libs'),
 
-    'EXTRA_PP_JS_MODULES': (StrictOrderingOnAppendList, list,
+    'EXTRA_PP_JS_MODULES': (HierarchicalStringList, list,
         """Additional JavaScript files to distribute.
 
         This variable contains a list of files to copy into
         ``$(FINAL_TARGET)/$(JS_MODULES_PATH)``, after preprocessing.
         ``JS_MODULES_PATH`` defaults to ``modules`` if left undefined.
         """, 'libs'),
 
     'TESTING_JS_MODULES': (HierarchicalStringList, list,

--- a/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build
+++ b/python/mozbuild/mozbuild/test/backend/data/variable_passthru/moz.build
@@ -2,19 +2,16 @@
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
 SOURCES += ['bar.s', 'foo.asm']
 
 EXTRA_COMPONENTS = ['bar.js', 'foo.js']
 EXTRA_PP_COMPONENTS = ['bar.pp.js', 'foo.pp.js']
 
-EXTRA_JS_MODULES += ['bar.jsm', 'foo.jsm']
-EXTRA_PP_JS_MODULES = ['bar.pp.jsm', 'foo.pp.jsm']
-
 HOST_SOURCES += ['bar.cpp', 'foo.cpp']
 HOST_SOURCES += ['bar.c', 'foo.c']
 
 OS_LIBS = ['foo.so', '-l123', 'bar.a']
 
 SOURCES += ['bar.c', 'foo.c']
 
 SOURCES += ['bar.mm', 'foo.mm']

--- a/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
+++ b/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
@@ -271,24 +271,16 @@ class TestRecursiveMakeBackend(BackendTe
             'EXTRA_COMPONENTS': [
                 'EXTRA_COMPONENTS += bar.js',
                 'EXTRA_COMPONENTS += foo.js',
             ],
             'EXTRA_PP_COMPONENTS': [
                 'EXTRA_PP_COMPONENTS += bar.pp.js',
                 'EXTRA_PP_COMPONENTS += foo.pp.js',
             ],
-            'EXTRA_JS_MODULES': [
-                'EXTRA_JS_MODULES += bar.jsm',
-                'EXTRA_JS_MODULES += foo.jsm',
-            ],
-            'EXTRA_PP_JS_MODULES': [
-                'EXTRA_PP_JS_MODULES += bar.pp.jsm',
-                'EXTRA_PP_JS_MODULES += foo.pp.jsm',
-            ],
             'FAIL_ON_WARNINGS': [
                 'FAIL_ON_WARNINGS := 1',
             ],
             'HOST_CPPSRCS': [
                 'HOST_CPPSRCS += bar.cpp',
                 'HOST_CPPSRCS += foo.cpp',
             ],
             'HOST_CSRCS': [

--- a/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build
+++ b/python/mozbuild/mozbuild/test/frontend/data/variable-passthru/moz.build
@@ -2,19 +2,16 @@
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
 SOURCES += ['fans.asm', 'tans.s']
 
 EXTRA_COMPONENTS=['fans.js', 'tans.js']
 EXTRA_PP_COMPONENTS=['fans.pp.js', 'tans.pp.js']
 
-EXTRA_JS_MODULES += ['bar.jsm', 'foo.jsm']
-EXTRA_PP_JS_MODULES = ['bar.pp.jsm', 'foo.pp.jsm']
-
 HOST_SOURCES += ['fans.cpp', 'tans.cpp']
 HOST_SOURCES += ['fans.c', 'tans.c']
 
 OS_LIBS += ['foo.so', '-l123', 'aaa.a']
 
 SOURCES += ['fans.c', 'tans.c']
 
 SOURCES += ['fans.mm', 'tans.mm']

--- a/python/mozbuild/mozbuild/test/frontend/test_emitter.py
+++ b/python/mozbuild/mozbuild/test/frontend/test_emitter.py
@@ -149,18 +149,16 @@ class TestEmitterBasic(unittest.TestCase
 
         wanted = dict(
             ASFILES=['fans.asm', 'tans.s'],
             CMMSRCS=['fans.mm', 'tans.mm'],
             CSRCS=['fans.c', 'tans.c'],
             DISABLE_STL_WRAPPING=True,
             EXTRA_COMPONENTS=['fans.js', 'tans.js'],
             EXTRA_PP_COMPONENTS=['fans.pp.js', 'tans.pp.js'],
-            EXTRA_JS_MODULES=['bar.jsm', 'foo.jsm'],
-            EXTRA_PP_JS_MODULES=['bar.pp.jsm', 'foo.pp.jsm'],
             FAIL_ON_WARNINGS=True,
             HOST_CPPSRCS=['fans.cpp', 'tans.cpp'],
             HOST_CSRCS=['fans.c', 'tans.c'],
             MSVC_ENABLE_PGO=True,
             NO_DIST_INSTALL=True,
             OS_LIBS=['foo.so', '-l123', 'aaa.a'],
             SSRCS=['bans.S', 'fans.S'],
             VISIBILITY_FLAGS='',

--- a/services/metrics/moz.build
+++ b/services/metrics/moz.build
@@ -1,19 +1,17 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 TEST_DIRS += ['tests']
 
-EXTRA_PP_JS_MODULES += [
+EXTRA_PP_JS_MODULES.services.metrics += [
     'dataprovider.jsm',
     'providermanager.jsm',
     'storage.jsm',
 ]
 
-JS_MODULES_PATH = 'modules/services/metrics'
-
 TESTING_JS_MODULES.services.metrics += [
     'modules-testing/mocks.jsm',
 ]

--- a/toolkit/components/osfile/modules/moz.build
+++ b/toolkit/components/osfile/modules/moz.build
@@ -1,17 +1,15 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/osfile'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.osfile += [
     'osfile_async_front.jsm',
     'osfile_async_worker.js',
     'osfile_native.jsm',
     'osfile_shared_allthreads.jsm',
     'osfile_shared_front.jsm',
     'osfile_unix_allthreads.jsm',
     'osfile_unix_back.jsm',
     'osfile_unix_front.jsm',

--- a/toolkit/components/promiseworker/worker/moz.build
+++ b/toolkit/components/promiseworker/worker/moz.build
@@ -1,11 +1,9 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/workers'
-
-EXTRA_JS_MODULES = [
+EXTRA_JS_MODULES.workers = [
     'PromiseWorker.js',
 ]

--- a/toolkit/components/sqlite/moz.build
+++ b/toolkit/components/sqlite/moz.build
@@ -1,13 +1,11 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/xpcshell/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/sqlite'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.sqlite += [
     'sqlite_internal.js',
 ]

--- a/toolkit/components/workerloader/moz.build
+++ b/toolkit/components/workerloader/moz.build
@@ -1,13 +1,11 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 MOCHITEST_CHROME_MANIFESTS += ['tests/chrome.ini']
 
-JS_MODULES_PATH = 'modules/workers'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.workers += [
     'require.js'
 ]

--- a/toolkit/components/workerlz4/moz.build
+++ b/toolkit/components/workerlz4/moz.build
@@ -1,19 +1,17 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/xpcshell/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/workers'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.workers += [
     'lz4.js',
     'lz4_internal.js',
 ]
 
 SOURCES += [
     'lz4.cpp',
 ]
 

--- a/toolkit/crashreporter/test/Makefile.in
+++ b/toolkit/crashreporter/test/Makefile.in
@@ -1,14 +1,14 @@
 #
 # 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/.
 
 EXTRA_LIBS += $(NSPR_LIBS)
 
-UNIT_FILES = $(SHARED_LIBRARY) $(EXTRA_JS_MODULES)
+UNIT_FILES = $(SHARED_LIBRARY) CrashTestUtils.jsm
 UNIT_DEST = $(DEPTH)/_tests/xpcshell/$(relativesrcdir)/unit/
 INSTALL_TARGETS += UNIT
 
 UNIT_IPC_FILES = $(UNIT_FILES)
 UNIT_IPC_DEST = $(DEPTH)/_tests/xpcshell/$(relativesrcdir)/unit_ipc/
 INSTALL_TARGETS += UNIT_IPC

--- a/toolkit/devtools/acorn/moz.build
+++ b/toolkit/devtools/acorn/moz.build
@@ -1,15 +1,13 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools/acorn'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.acorn += [
     'acorn.js',
     'acorn_loose.js',
     'walk.js',
 ]

--- a/toolkit/devtools/apps/moz.build
+++ b/toolkit/devtools/apps/moz.build
@@ -1,14 +1,12 @@
 # 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/.
 
 TEST_DIRS += ['tests']
 
-JS_MODULES_PATH = 'modules/devtools'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools += [
     'app-actor-front.js',
     'Devices.jsm',
     'Simulator.jsm'
 ]

--- a/toolkit/devtools/discovery/moz.build
+++ b/toolkit/devtools/discovery/moz.build
@@ -1,13 +1,11 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 TEST_DIRS += ['tests']
 
-JS_MODULES_PATH = 'modules/devtools/discovery'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.discovery += [
     'discovery.js',
 ]

--- a/toolkit/devtools/jsbeautify/moz.build
+++ b/toolkit/devtools/jsbeautify/moz.build
@@ -1,19 +1,17 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools/jsbeautify'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.jsbeautify += [
     'beautify.js',
     'lib/sanitytest.js',
     'lib/urlencode_unpacker.js',
     'src/beautify-css.js',
     'src/beautify-html.js',
     'src/beautify-js.js',
     'src/beautify-tests.js'
 ]

--- a/toolkit/devtools/pretty-fast/moz.build
+++ b/toolkit/devtools/pretty-fast/moz.build
@@ -1,13 +1,11 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools += [
     'pretty-fast.js',
 ]

--- a/toolkit/devtools/qrcode/decoder/moz.build
+++ b/toolkit/devtools/qrcode/decoder/moz.build
@@ -1,11 +1,9 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/qrcode/decoder'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.qrcode.decoder += [
     'index.js',
 ]

--- a/toolkit/devtools/qrcode/encoder/moz.build
+++ b/toolkit/devtools/qrcode/encoder/moz.build
@@ -1,11 +1,9 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/qrcode/encoder'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.qrcode.encoder += [
     'index.js',
 ]

--- a/toolkit/devtools/qrcode/moz.build
+++ b/toolkit/devtools/qrcode/moz.build
@@ -4,16 +4,14 @@
 # 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/.
 
 DIRS += [
     'decoder',
     'encoder'
 ]
 
-JS_MODULES_PATH = 'modules/devtools/qrcode'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.qrcode += [
     'index.js',
 ]
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
 MOCHITEST_CHROME_MANIFESTS += ['tests/mochitest/chrome.ini']

--- a/toolkit/devtools/styleinspector/moz.build
+++ b/toolkit/devtools/styleinspector/moz.build
@@ -1,11 +1,9 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/devtools/styleinspector'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.styleinspector += [
     'css-logic.js'
 ]

--- a/toolkit/devtools/tern/moz.build
+++ b/toolkit/devtools/tern/moz.build
@@ -1,19 +1,17 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools/tern'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.tern += [
     'browser.js',
     'comment.js',
     'condense.js',
     'def.js',
     'ecma5.js',
     'infer.js',
     'signal.js',
     'tern.js',

--- a/toolkit/devtools/transport/moz.build
+++ b/toolkit/devtools/transport/moz.build
@@ -1,15 +1,13 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
 TEST_DIRS += ['tests']
 
-JS_MODULES_PATH = 'modules/devtools/transport'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.transport += [
     'packets.js',
     'stream-utils.js',
     'transport.js'
 ]

--- a/toolkit/devtools/webconsole/moz.build
+++ b/toolkit/devtools/webconsole/moz.build
@@ -3,16 +3,14 @@
 # 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['OS_TARGET'] != 'Android':
     MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
     XPCSHELL_TESTS_MANIFESTS += ['test/unit/xpcshell.ini']
 
-JS_MODULES_PATH = 'modules/devtools/toolkit/webconsole'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.devtools.toolkit.webconsole += [
     'client.js',
     'network-helper.js',
     'network-monitor.js',
     'utils.js',
 ]

--- a/toolkit/identity/moz.build
+++ b/toolkit/identity/moz.build
@@ -12,29 +12,27 @@ XPIDL_SOURCES += [
 ]
 
 XPIDL_MODULE = 'identity'
 
 SOURCES += [
     'IdentityCryptoService.cpp',
 ]
 
-JS_MODULES_PATH = 'modules/identity'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.identity += [
     'Identity.jsm',
     'IdentityProvider.jsm',
     'IdentityStore.jsm',
     'IdentityUtils.jsm',
     'jwcrypto.jsm',
     'LogUtils.jsm',
     'MinimalIdentity.jsm',
     'RelyingParty.jsm',
     'Sandbox.jsm',
 ]
 
-EXTRA_PP_JS_MODULES += [
+EXTRA_PP_JS_MODULES.identity += [
     'FirefoxAccounts.jsm',
 ]
 
 FAIL_ON_WARNINGS = True
 
 FINAL_LIBRARY = 'xul'

--- a/toolkit/mozapps/extensions/internal/moz.build
+++ b/toolkit/mozapps/extensions/internal/moz.build
@@ -1,29 +1,27 @@
 # -*- Mode: python; c-basic-offset: 4; 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/.
 
-JS_MODULES_PATH = 'modules/addons'
-
-EXTRA_JS_MODULES += [
+EXTRA_JS_MODULES.addons += [
     'AddonLogging.jsm',
     'AddonRepository.jsm',
     'AddonRepository_SQLiteMigrator.jsm',
     'AddonUpdateChecker.jsm',
     'Content.js',
     'LightweightThemeImageOptimizer.jsm',
     'OpenH264Provider.jsm',
     'PluginProvider.jsm',
     'SpellCheckDictionaryBootstrap.js',
 ]
 
-EXTRA_PP_JS_MODULES += [
+EXTRA_PP_JS_MODULES.addons += [
     'XPIProvider.jsm',
     'XPIProviderUtils.js',
 ]
 
 # This is used in multiple places, so is defined here to avoid it getting
 # out of sync.
 DEFINES['MOZ_EXTENSIONS_DB_SCHEMA'] = 16