--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -270,8 +270,61 @@ class ClangCommands(MachCommandBase):
 
 @CommandProvider
 class Package(MachCommandBase):
     """Package the built product for distribution."""
 
     @Command('package', help='Package the built product for distribution as an APK, DMG, etc.')
     def package(self):
         return self._run_make(directory=".", target='package', ensure_exit_code=False)
+
+
+@CommandProvider
+class Makefiles(MachCommandBase):
+    @Command('empty-makefiles', help='Find empty Makefile.in in the tree.')
+    def empty(self):
+        import pymake.parser
+        import pymake.parserdata
+
+        IGNORE_VARIABLES = {
+            'DEPTH': ('@DEPTH@',),
+            'topsrcdir': ('@top_srcdir@',),
+            'srcdir': ('@srcdir@',),
+            'relativesrcdir': ('@relativesrcdir@',),
+            'VPATH': ('@srcdir@',),
+        }
+
+        IGNORE_INCLUDES = [
+            'include $(DEPTH)/config/autoconf.mk',
+            'include $(topsrcdir)/config/config.mk',
+            'include $(topsrcdir)/config/rules.mk',
+        ]
+
+        def is_statement_relevant(s):
+            if isinstance(s, pymake.parserdata.SetVariable):
+                exp = s.vnameexp
+                if not exp.is_static_string:
+                    return True
+
+                if exp.s not in IGNORE_VARIABLES:
+                    return True
+
+                return s.value not in IGNORE_VARIABLES[exp.s]
+
+            if isinstance(s, pymake.parserdata.Include):
+                if s.to_source() in IGNORE_INCLUDES:
+                    return False
+
+            return True
+
+        for path in self._makefile_ins():
+            statements = [s for s in pymake.parser.parsefile(path)
+                if is_statement_relevant(s)]
+
+            if not statements:
+                print(os.path.relpath(path, self.topsrcdir))
+
+    def _makefile_ins(self):
+        for root, dirs, files in os.walk(self.topsrcdir):
+            for f in files:
+                if f == 'Makefile.in':
+                    yield os.path.join(root, f)
+

deleted file mode 100644
--- a/toolkit/toolkit-tiers.mk
+++ /dev/null
@@ -1,352 +0,0 @@
-# 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/.
-
-ifdef LIBXUL_SDK
-$(error toolkit-tiers.mk is not compatible with --enable-libxul-sdk=)
-endif
-
-TIERS += nspr
-
-ifndef MOZ_NATIVE_NSPR
-tier_nspr_staticdirs += nsprpub
-tier_nspr_dirs += config/nspr
-endif
-
-TIERS += nss
-
-ifndef MOZ_NATIVE_SQLITE
-tier_nss_dirs += db/sqlite3/src
-endif
-
-ifdef MOZ_PSM
-ifndef MOZ_NATIVE_NSS
-tier_nss_dirs += security/build
-endif
-endif
-
-include $(topsrcdir)/config/js/build.mk
-
-TIERS += platform
-
-ifdef NS_TRACE_MALLOC
-tier_platform_dirs = tools/trace-malloc/lib
-endif
-
-ifdef MOZ_DMD
-tier_platform_dirs += memory/replace/dmd
-endif
-
-ifdef MOZ_TREE_FREETYPE
-tier_platform_staticdirs += modules/freetype2
-endif
-
-tier_platform_dirs += xpcom
-
-tier_platform_dirs += \
-		modules/libpref \
-		intl \
-		netwerk \
-		$(NULL)
-
-ifdef MOZ_AUTH_EXTENSION
-tier_platform_dirs += extensions/auth
-endif
-
-#
-# "external" - 3rd party individual libraries
-#
-
-ifndef MOZ_NATIVE_JPEG
-tier_platform_dirs	+= media/libjpeg
-endif
-
-ifdef MOZ_UPDATER
-ifndef MOZ_NATIVE_BZ2
-tier_platform_dirs += modules/libbz2
-endif
-tier_platform_dirs += other-licenses/bsdiff
-endif
-
-tier_platform_dirs	+= gfx/qcms
-
-#
-# "gecko" - core components
-#
-
-tier_platform_dirs += ipc js/ipc
-
-tier_platform_dirs += \
-		hal \
-		js/xpconnect \
-		intl/chardet \
-		$(NULL)
-
-ifdef MOZ_ENABLE_GTK2
-ifdef MOZ_X11
-tier_platform_dirs     += widget/gtkxtbin
-endif
-endif
-
-tier_platform_dirs	+= \
-		modules/libjar \
-		storage \
-		$(NULL)
-
-ifdef MOZ_PERMISSIONS
-tier_platform_dirs += \
-		extensions/cookie \
-		extensions/permissions \
-		$(NULL)
-endif
-
-tier_platform_dirs += rdf
-
-ifdef MOZ_JSDEBUGGER
-tier_platform_dirs += js/jsd
-endif
-
-ifdef MOZ_VORBIS
-tier_platform_dirs += \
-		media/libvorbis \
-		$(NULL)
-endif
-
-ifdef MOZ_TREMOR
-tier_platform_dirs += \
-		media/libtremor \
-		$(NULL)
-endif
-
-ifdef MOZ_OPUS
-tier_platform_dirs += \
-  media/libopus \
-  $(NULL)
-endif
-
-ifdef MOZ_WEBM
-tier_platform_dirs += media/libnestegg
-endif
-
-ifdef MOZ_VP8
-ifndef MOZ_NATIVE_LIBVPX
-tier_platform_dirs += media/libvpx
-endif
-endif
-
-ifdef MOZ_OGG
-tier_platform_dirs += \
-		media/libogg \
-		media/libtheora \
-		$(NULL)
-endif
-
-ifdef MOZ_WEBVTT
-tier_platform_dirs += \
-		media/webvtt \
-		$(NULL)
-endif
-
-ifdef MOZ_SYDNEYAUDIO
-tier_platform_dirs += \
-		media/libsydneyaudio \
-		$(NULL)
-endif
-
-ifdef MOZ_WEBRTC
-tier_platform_dirs += \
-  media/webrtc \
-  media/mtransport/third_party \
-  media/mtransport/build \
-  media/mtransport/standalone \
-  $(NULL)
-endif
-
-ifdef MOZ_SPEEX_RESAMPLER
-tier_platform_dirs += \
-		media/libspeex_resampler \
-		$(NULL)
-endif
-
-ifdef MOZ_SOUNDTOUCH
-tier_platform_dirs += \
-		media/libsoundtouch \
-		$(NULL)
-endif
-
-ifdef MOZ_CUBEB
-tier_platform_dirs += \
-		media/libcubeb \
-		$(NULL)
-endif
-
-ifdef MOZ_OMX_PLUGIN
-tier_platform_dirs += \
-		media/omx-plugin/lib/ics/libutils \
-		media/omx-plugin/lib/ics/libstagefright \
-		media/omx-plugin/lib/gb/libutils \
-		media/omx-plugin/lib/gb/libstagefright \
-		media/omx-plugin/lib/gb/libstagefright_color_conversion \
-		media/omx-plugin/lib/gb235/libstagefright \
-		media/omx-plugin/lib/froyo/libstagefright \
-		media/omx-plugin \
-		media/omx-plugin/gb \
-		media/omx-plugin/gb235 \
-		media/omx-plugin/froyo \
-		media/omx-plugin/lib/hc/libstagefright \
-		media/omx-plugin/hc \
-		media/omx-plugin/sony \
-		$(NULL)
-endif
-
-ifndef MOZ_NATIVE_PNG
-tier_platform_dirs += media/libpng
-endif
-
-ifdef ENABLE_TESTS
-tier_platform_dirs += testing/specialpowers
-endif
-
-ifdef MOZ_ENABLE_GTEST
-tier_platform_dirs += testing/gtest
-endif
-
-tier_platform_dirs	+= \
-		uriloader \
-		caps \
-		parser \
-		gfx \
-		image \
-		dom \
-		view \
-		widget \
-		content \
-		editor \
-		layout \
-		docshell \
-		embedding \
-		xpfe/appshell \
-		$(NULL)
-
-# This needs to be built after the gfx/ directory
-# to ensure all dependencies for skia (e.g. mozalloc, xpcom)
-# have been built
-ifeq (android,$(MOZ_WIDGET_TOOLKIT))
-tier_platform_dirs += other-licenses/skia-npapi
-endif
-
-ifdef MOZ_UNIVERSALCHARDET
-tier_platform_dirs += extensions/universalchardet
-endif
-
-ifdef ACCESSIBILITY
-tier_platform_dirs    += accessible
-endif
-
-#
-# "toolkit" - xpfe & toolkit
-#
-
-tier_platform_dirs += profile
-
-# This must precede xpfe
-ifdef MOZ_JPROF
-tier_platform_dirs        += tools/jprof
-endif
-
-tier_platform_dirs  += tools/profiler
-
-tier_platform_dirs	+= xpfe/components
-
-ifdef MOZ_ENABLE_XREMOTE
-tier_platform_dirs += widget/xremoteclient
-endif
-
-ifdef MOZ_SPELLCHECK
-tier_platform_dirs	+= extensions/spellcheck
-endif
-
-ifdef MOZ_PSM
-tier_platform_dirs	+= security/manager
-else
-tier_platform_dirs	+= security/manager/boot/public security/manager/ssl/public
-endif
-
-ifdef MOZ_UPDATER
-tier_platform_dirs += modules/libmar
-endif
-
-tier_platform_dirs	+= toolkit
-
-ifdef MOZ_PREF_EXTENSIONS
-tier_platform_dirs += extensions/pref
-endif
-
-tier_platform_dirs += services
-
-tier_platform_dirs += startupcache
-
-tier_platform_dirs += js/ductwork/debugger
-
-tier_platform_dirs += other-licenses/snappy
-
-ifdef MOZ_GIO_COMPONENT
-tier_platform_dirs += extensions/gio
-endif
-
-ifdef APP_LIBXUL_STATICDIRS
-# Applications can cheat and ask for code to be
-# built before libxul so libxul can be linked against it.
-tier_platform_staticdirs += $(APP_LIBXUL_STATICDIRS)
-endif
-ifdef APP_LIBXUL_DIRS
-# Applications can cheat and ask for code to be
-# built before libxul so it can be linked into libxul.
-tier_platform_dirs += $(APP_LIBXUL_DIRS)
-endif
-
-tier_platform_dirs += toolkit/library
-
-tier_platform_dirs += xpcom/stub
-
-ifdef MOZ_REPLACE_MALLOC
-tier_platform_dirs += memory/replace
-endif
-
-ifdef NS_TRACE_MALLOC
-tier_platform_dirs += tools/trace-malloc
-endif
-
-ifdef MOZ_ENABLE_GNOME_COMPONENT
-tier_platform_dirs    += toolkit/system/gnome
-endif
-
-ifndef MOZ_ENABLE_LIBCONIC
-# if libconic is present, it will do its own network monitoring
-ifdef MOZ_ENABLE_DBUS
-tier_platform_dirs    += toolkit/system/dbus
-endif
-endif
-
-tier_platform_dirs += addon-sdk
-
-ifdef MOZ_MAPINFO
-tier_platform_dirs	+= tools/codesighs
-endif
-
-ifdef ENABLE_MARIONETTE
-tier_platform_dirs += testing/marionette
-endif
-
-ifdef ENABLE_TESTS
-tier_platform_dirs += testing/mochitest
-tier_platform_dirs += testing/xpcshell
-tier_platform_dirs += testing/tools/screenshot
-tier_platform_dirs += testing/peptest
-tier_platform_dirs += testing/mozbase
-tier_platform_dirs += testing/modules
-ifdef MOZ_WEBRTC
-tier_platform_dirs += media/webrtc/signaling/test
-tier_platform_dirs += media/mtransport/test
-endif
-endif