--- a/Makefile.in
+++ b/Makefile.in
@@ -29,26 +29,28 @@ DIST_GARBAGE = config.cache config.log c
    .mozconfig.mk
 
 ifdef JS_STANDALONE
 configure_dir = $(topsrcdir)/js/src
 else
 configure_dir = $(topsrcdir)
 endif
 
+ifndef TEST_MOZBUILD
 ifndef MOZ_PROFILE_USE
 # We need to explicitly put backend.RecursiveMakeBackend here
 # otherwise the rule in rules.mk doesn't run early enough.
 $(TIERS) binaries:: CLOBBER $(configure_dir)/configure config.status backend.RecursiveMakeBackend
 ifndef JS_STANDALONE
 ifdef COMPILE_ENVIRONMENT
 $(TIERS) binaries:: $(topsrcdir)/js/src/configure js/src/config.status
 endif
 endif
 endif
+endif
 
 ifdef JS_STANDALONE
 .PHONY: CLOBBER
 CLOBBER:
 else
 CLOBBER: $(topsrcdir)/CLOBBER
 	@echo 'STOP!  The CLOBBER file has changed.'
 	@echo 'Please run the build through a sanctioned build wrapper, such as'
@@ -76,26 +78,28 @@ config.status js/src/config.status:
 
 # Regenerate the build backend if it is out of date. We only have this rule in
 # this main make file because having it in rules.mk and applied to partial tree
 # builds resulted in a world of hurt. Gory details are in bug 877308.
 #
 # The mach build driver will ensure the backend is up to date for partial tree
 # builds. This cleanly avoids most of the pain.
 
+ifndef TEST_MOZBUILD
 backend.RecursiveMakeBackend:
 	@echo 'Build configuration changed. Regenerating backend.'
 	$(PYTHON) config.status
 
 Makefile: backend.RecursiveMakeBackend
 	@$(TOUCH) $@
 
 include backend.RecursiveMakeBackend.pp
 
 default:: backend.RecursiveMakeBackend
+endif
 
 install_manifests := \
   $(addprefix dist/,bin branding idl include public private sdk xpi-stage) \
   _tests \
   $(NULL)
 install_manifest_depends = \
   CLOBBER \
   $(configure_dir)/configure \

--- a/config/faster/rules.mk
+++ b/config/faster/rules.mk
@@ -38,25 +38,30 @@
 # global Make variables names are uppercase, while "local" Make variables
 # applied to specific targets are lowercase.
 
 # Targets to be triggered for a default build
 default: $(addprefix install-,$(INSTALL_MANIFESTS))
 
 # Explicit files to be built for a default build
 default: $(addprefix $(TOPOBJDIR)/,$(MANIFEST_TARGETS))
+ifndef TEST_MOZBUILD
 default: $(TOPOBJDIR)/dist/bin/platform.ini
+endif
 
 ifndef NO_XPIDL
 # Targets from the recursive make backend to be built for a default build
 default: $(TOPOBJDIR)/config/makefiles/xpidl/xpidl
 endif
 
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 # Mac builds require to copy things in dist/bin/*.app
+# TODO: remove the MOZ_WIDGET_TOOLKIT and MOZ_BUILD_APP variables from
+# faster/Makefile and python/mozbuild/mozbuild/test/backend/test_build.py
+# when this is not required anymore.
 default:
 	$(MAKE) -C $(TOPOBJDIR)/$(MOZ_BUILD_APP)/app repackage
 endif
 
 .PHONY: FORCE
 
 # Extra define to trigger some workarounds. We should strive to limit the
 # use of those. As of writing the only ones are in

--- a/python/moz.build
+++ b/python/moz.build
@@ -30,16 +30,17 @@ PYTHON_UNIT_TESTS += [
     'mozbuild/dumbmake/test/__init__.py',
     'mozbuild/dumbmake/test/test_dumbmake.py',
     'mozbuild/mozbuild/test/__init__.py',
     'mozbuild/mozbuild/test/action/test_buildlist.py',
     'mozbuild/mozbuild/test/action/test_generate_browsersearch.py',
     'mozbuild/mozbuild/test/backend/__init__.py',
     'mozbuild/mozbuild/test/backend/common.py',
     'mozbuild/mozbuild/test/backend/test_android_eclipse.py',
+    'mozbuild/mozbuild/test/backend/test_build.py',
     'mozbuild/mozbuild/test/backend/test_configenvironment.py',
     'mozbuild/mozbuild/test/backend/test_recursivemake.py',
     'mozbuild/mozbuild/test/backend/test_visualstudio.py',
     'mozbuild/mozbuild/test/common.py',
     'mozbuild/mozbuild/test/compilation/__init__.py',
     'mozbuild/mozbuild/test/compilation/test_warnings.py',
     'mozbuild/mozbuild/test/controller/__init__.py',
     'mozbuild/mozbuild/test/controller/test_ccachestats.py',

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/app/moz.build
@@ -0,0 +1,49 @@
+DIST_SUBDIR = 'app'
+
+EXTRA_JS_MODULES += [
+    '../foo.jsm',
+]
+
+EXTRA_JS_MODULES.child += [
+    '../bar.jsm',
+]
+
+EXTRA_PP_JS_MODULES += [
+    '../baz.jsm',
+]
+
+EXTRA_PP_JS_MODULES.child2 += [
+    '../qux.jsm',
+]
+
+FINAL_TARGET_FILES += [
+    '../foo.ini',
+]
+
+FINAL_TARGET_FILES.child += [
+    '../bar.ini',
+]
+
+FINAL_TARGET_PP_FILES += [
+    '../baz.ini',
+]
+
+FINAL_TARGET_PP_FILES.child2 += [
+    '../qux.ini',
+]
+
+EXTRA_COMPONENTS += [
+    '../components.manifest',
+    '../foo.js',
+]
+
+EXTRA_PP_COMPONENTS += [
+    '../bar.js',
+]
+
+JS_PREFERENCE_FILES += [
+    '../prefs.js',
+]
+
+DEFINES['FOO'] = 'bar'
+DEFINES['BAR'] = True

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/bar.ini
@@ -0,0 +1,1 @@
+bar.ini

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/bar.js
@@ -0,0 +1,2 @@
+#filter substitution
+bar.js: FOO is @FOO@

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/bar.jsm
@@ -0,0 +1,1 @@
+bar.jsm

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/baz.ini
@@ -0,0 +1,2 @@
+#filter substitution
+baz.ini: FOO is @FOO@

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/baz.jsm
@@ -0,0 +1,2 @@
+#filter substitution
+baz.jsm: FOO is @FOO@

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/components.manifest
@@ -0,0 +1,2 @@
+component {foo} foo.js
+component {bar} bar.js

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/foo.ini
@@ -0,0 +1,1 @@
+foo.ini

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/foo.js
@@ -0,0 +1,1 @@
+foo.js

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/foo.jsm
@@ -0,0 +1,1 @@
+foo.jsm

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/moz.build
@@ -0,0 +1,63 @@
+CONFIGURE_SUBST_FILES += [
+    '/config/autoconf.mk',
+    '/config/emptyvars.mk',
+]
+
+EXTRA_JS_MODULES += [
+    'foo.jsm',
+]
+
+EXTRA_JS_MODULES.child += [
+    'bar.jsm',
+]
+
+EXTRA_PP_JS_MODULES += [
+    'baz.jsm',
+]
+
+EXTRA_PP_JS_MODULES.child2 += [
+    'qux.jsm',
+]
+
+FINAL_TARGET_FILES += [
+    'foo.ini',
+]
+
+FINAL_TARGET_FILES.child += [
+    'bar.ini',
+]
+
+FINAL_TARGET_PP_FILES += [
+    'baz.ini',
+]
+
+FINAL_TARGET_PP_FILES.child2 += [
+    'qux.ini',
+]
+
+EXTRA_COMPONENTS += [
+    'components.manifest',
+    'foo.js',
+]
+
+EXTRA_PP_COMPONENTS += [
+    'bar.js',
+]
+
+JS_PREFERENCE_FILES += [
+    'prefs.js',
+]
+
+RESOURCE_FILES += [
+    'resource',
+]
+
+RESOURCE_FILES.child += [
+    'resource2',
+]
+
+DEFINES['FOO'] = 'foo'
+
+DIRS += [
+    'app',
+]

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/prefs.js
@@ -0,0 +1,1 @@
+prefs.js

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/qux.ini
@@ -0,0 +1,5 @@
+#ifdef BAR
+qux.ini: BAR is defined
+#else
+qux.ini: BAR is not defined
+#endif

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/qux.jsm
@@ -0,0 +1,5 @@
+#ifdef BAR
+qux.jsm: BAR is defined
+#else
+qux.jsm: BAR is not defined
+#endif

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/resource
@@ -0,0 +1,1 @@
+resource

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/build/resource2
@@ -0,0 +1,1 @@
+resource2

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/test_build.py
@@ -0,0 +1,166 @@
+# 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/.
+
+from __future__ import unicode_literals, print_function
+
+import buildconfig
+import os
+import shutil
+import sys
+import unittest
+import mozpack.path as mozpath
+from contextlib import contextmanager
+from mozunit import main
+from mozbuild.backend.configenvironment import ConfigEnvironment
+from mozbuild.backend.recursivemake import RecursiveMakeBackend
+from mozbuild.backend.fastermake import FasterMakeBackend
+from mozbuild.base import MozbuildObject
+from mozbuild.frontend.emitter import TreeMetadataEmitter
+from mozbuild.frontend.reader import BuildReader
+from mozbuild.util import ensureParentDir
+from mozpack.files import FileFinder
+from tempfile import mkdtemp
+
+
+BASE_SUBSTS = [
+    ('PYTHON', sys.executable),
+]
+
+
+class TestBuild(unittest.TestCase):
+    @contextmanager
+    def do_test_backend(self, *backends, **kwargs):
+        topobjdir = mkdtemp()
+        try:
+            config = ConfigEnvironment(buildconfig.topsrcdir, topobjdir,
+                                       **kwargs)
+            reader = BuildReader(config)
+            emitter = TreeMetadataEmitter(config)
+            moz_build = mozpath.join(config.topsrcdir, 'test.mozbuild')
+            definitions = list(emitter.emit(
+                reader.read_mozbuild(moz_build, config)))
+            for backend in backends:
+                backend(config).consume(definitions)
+
+            yield config
+        except:
+            raise
+        finally:
+            if not os.environ.get('MOZ_NO_CLEANUP'):
+                shutil.rmtree(topobjdir)
+
+    @contextmanager
+    def line_handler(self):
+        lines = []
+
+        def handle_make_line(line):
+            lines.append(line)
+
+        try:
+            yield handle_make_line
+        except:
+            print('\n'.join(lines))
+            raise
+
+        if os.environ.get('MOZ_VERBOSE_MAKE'):
+            print('\n'.join(lines))
+
+    def test_recursive_make(self):
+        substs = list(BASE_SUBSTS)
+        with self.do_test_backend(RecursiveMakeBackend,
+                                  substs=substs) as config:
+            build = MozbuildObject(config.topsrcdir, None, None,
+                                   config.topobjdir)
+            overrides = [
+                'install_manifest_depends=',
+                'TEST_MOZBUILD=1',
+            ]
+            with self.line_handler() as handle_make_line:
+                build._run_make(directory=config.topobjdir, target=overrides,
+                                silent=False, line_handler=handle_make_line)
+
+            self.validate(config)
+
+    def test_faster_make(self):
+        substs = list(BASE_SUBSTS) + [
+            ('MOZ_BUILD_APP', 'dummy_app'),
+            ('MOZ_WIDGET_TOOLKIT', 'dummy_widget'),
+        ]
+        with self.do_test_backend(RecursiveMakeBackend, FasterMakeBackend,
+                                  substs=substs) as config:
+            buildid = mozpath.join(config.topobjdir, 'config', 'buildid')
+            ensureParentDir(buildid)
+            with open(buildid, 'w') as fh:
+                fh.write('20100101012345\n')
+
+            build = MozbuildObject(config.topsrcdir, None, None,
+                                   config.topobjdir)
+            overrides = [
+                'TEST_MOZBUILD=1',
+            ]
+            with self.line_handler() as handle_make_line:
+                build._run_make(directory=mozpath.join(config.topobjdir,
+                                                       'faster'),
+                                target=overrides, silent=False,
+                                line_handler=handle_make_line)
+
+            self.validate(config)
+
+    def validate(self, config):
+        self.maxDiff = None
+        test_path = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                 'data', 'build') + os.sep
+
+        # We want unicode instances out of the files, because having plain str
+        # makes assertEqual diff output in case of error extra verbose because
+        # of the difference in type.
+        result = {
+            p: f.open().read().decode('utf-8')
+            for p, f in FileFinder(mozpath.join(config.topobjdir, 'dist'))
+        }
+        self.assertTrue(len(result))
+        self.assertEqual(result, {
+            'bin/baz.ini': 'baz.ini: FOO is foo\n',
+            'bin/child/bar.ini': 'bar.ini\n',
+            'bin/child2/qux.ini': 'qux.ini: BAR is not defined\n',
+            'bin/chrome.manifest': 'manifest components/components.manifest\n',
+            'bin/components/bar.js':
+                '//@line 2 "%sbar.js"\nbar.js: FOO is foo\n' % (test_path),
+            'bin/components/components.manifest':
+                'component {foo} foo.js\ncomponent {bar} bar.js\n',
+            'bin/components/foo.js': 'foo.js\n',
+            'bin/defaults/pref/prefs.js': 'prefs.js\n',
+            'bin/foo.ini': 'foo.ini\n',
+            'bin/modules/baz.jsm':
+                '//@line 2 "%sbaz.jsm"\nbaz.jsm: FOO is foo\n' % (test_path),
+            'bin/modules/child/bar.jsm': 'bar.jsm\n',
+            'bin/modules/child2/qux.jsm':
+                '//@line 4 "%squx.jsm"\nqux.jsm: BAR is not defined\n'
+                % (test_path),
+            'bin/modules/foo.jsm': 'foo.jsm\n',
+            'bin/res/resource': 'resource\n',
+            'bin/res/child/resource2': 'resource2\n',
+
+            'bin/app/baz.ini': 'baz.ini: FOO is bar\n',
+            'bin/app/child/bar.ini': 'bar.ini\n',
+            'bin/app/child2/qux.ini': 'qux.ini: BAR is defined\n',
+            'bin/app/chrome.manifest': 'manifest components/components.manifest\n',
+            'bin/app/components/bar.js':
+                '//@line 2 "%sbar.js"\nbar.js: FOO is bar\n' % (test_path),
+            'bin/app/components/components.manifest':
+                'component {foo} foo.js\ncomponent {bar} bar.js\n',
+            'bin/app/components/foo.js': 'foo.js\n',
+            'bin/app/defaults/preferences/prefs.js': 'prefs.js\n',
+            'bin/app/foo.ini': 'foo.ini\n',
+            'bin/app/modules/baz.jsm':
+                '//@line 2 "%sbaz.jsm"\nbaz.jsm: FOO is bar\n' % (test_path),
+            'bin/app/modules/child/bar.jsm': 'bar.jsm\n',
+            'bin/app/modules/child2/qux.jsm':
+                '//@line 2 "%squx.jsm"\nqux.jsm: BAR is defined\n'
+                % (test_path),
+            'bin/app/modules/foo.jsm': 'foo.jsm\n',
+        })
+
+if __name__ == '__main__':
+    main()

new file mode 100644
--- /dev/null
+++ b/test.mozbuild
@@ -0,0 +1,10 @@
+# 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/.
+
+# This file is necessary to "bootstrap" the test case for the test_build
+# test, because of the requirement of the top-level directory containing
+# config/*.mk.
+DIRS += [
+    'python/mozbuild/mozbuild/test/backend/data/build',
+]