--- a/config/config.mk
+++ b/config/config.mk
@@ -376,18 +376,30 @@ else
 MAKE_JARS_FLAGS += -c $(LOCALE_SRCDIR)
 endif # ! relativesrcdir
 
 ifdef IS_LANGUAGE_REPACK
 MERGE_FILE = $(firstword \
   $(wildcard $(REAL_LOCALE_MERGEDIR)/$(subst /locales,,$(LOCALE_RELATIVEDIR))/$(1)) \
   $(wildcard $(LOCALE_SRCDIR)/$(1)) \
   $(srcdir)/en-US/$(1) )
+# Like MERGE_FILE, but with the specified relative source directory
+# $(2) replacing $(srcdir).  It's expected that $(2) will include
+# '/locales' but not '/locales/en-US'.
+#
+# MERGE_RELATIVE_FILE and MERGE_FILE could be -- ahem -- merged by
+# making the second argument optional, but that expression makes for
+# difficult to read Make.
+MERGE_RELATIVE_FILE = $(firstword \
+  $(wildcard $(REAL_LOCALE_MERGEDIR)/$(subst /locales,,$(2))/$(1)) \
+  $(wildcard $(call EXPAND_LOCALE_SRCDIR,$(2))/$(1)) \
+  $(topsrcdir)/$(2)/en-US/$(1) )
 else
 MERGE_FILE = $(LOCALE_SRCDIR)/$(1)
+MERGE_RELATIVE_FILE = $(call EXPAND_LOCALE_SRCDIR,$(2))/$(1)
 endif
 
 ifneq (WINNT,$(OS_ARCH))
 RUN_TEST_PROGRAM = $(DIST)/bin/run-mozilla.sh
 endif # ! WINNT
 
 #
 # Java macros

--- a/mobile/android/base/locales/Makefile.in
+++ b/mobile/android/base/locales/Makefile.in
@@ -53,48 +53,8 @@ strings-xml-preqs =\
       $(ACDEFINES) \
 	  -DANDROID_PACKAGE_NAME=$(ANDROID_PACKAGE_NAME) \
 	  -DBRANDPATH='$(BRANDPATH)' \
 	  -DMOZ_APP_DISPLAYNAME='@MOZ_APP_DISPLAYNAME@' \
 	  -DSTRINGSPATH='$(STRINGSPATH)' \
 	  -DSYNCSTRINGSPATH='$(SYNCSTRINGSPATH)' \
       $< \
 	  -o $@)
-
-# Arg 1: Valid Make identifier, like suggestedsites.
-# Arg 2: File name, like suggestedsites.json.
-define generated_file_template
-
-# Determine the ../res/raw[-*] path.  This can be ../res/raw when no
-# locale is explicitly specified.
-$(1)-bypath = $(filter %/$(2),$(MAKECMDGOALS))
-ifeq (,$$(strip $$($(1)-bypath)))
-  $(1)-bypath = $($(1))
-endif
-$(1)-dstdir-raw = $$(patsubst %/,%,$$(dir $$($(1)-bypath)))
-
-GARBAGE += $($(1))
-
-libs realchrome:: $($(1))
-endef
-
-# L10NBASEDIR is not defined for en-US.
-l10n-srcdir := $(if $(filter en-US,$(AB_CD)),,$(or $(realpath $(L10NBASEDIR)),$(abspath $(L10NBASEDIR)))/$(AB_CD)/mobile/chrome)
-
-$(eval $(call generated_file_template,suggestedsites,suggestedsites.json))
-
-$(suggestedsites-dstdir-raw)/suggestedsites.json: FORCE
-	$(call py_action,generate_suggestedsites, \
-		--verbose \
-		--android-package-name=$(ANDROID_PACKAGE_NAME) \
-		--resources=$(topsrcdir)/mobile/android/app/src/photon/res \
-		$(if $(filter en-US,$(AB_CD)),,--srcdir=$(l10n-srcdir)) \
-		--srcdir=$(topsrcdir)/mobile/locales/en-US/chrome \
-		$@)
-
-$(eval $(call generated_file_template,browsersearch,browsersearch.json))
-
-$(browsersearch-dstdir-raw)/browsersearch.json: FORCE
-	$(call py_action,generate_browsersearch, \
-		--verbose \
-		$(if $(filter en-US,$(AB_CD)),,--srcdir=$(l10n-srcdir)) \
-		--srcdir=$(topsrcdir)/mobile/locales/en-US/chrome \
-		$@)

rename from python/mozbuild/mozbuild/action/generate_browsersearch.py
rename to mobile/android/base/locales/generate_browsersearch.py
--- a/python/mozbuild/mozbuild/action/generate_browsersearch.py
+++ b/mobile/android/base/locales/generate_browsersearch.py
@@ -3,19 +3,19 @@
 # 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/.
 
 '''
 Script to generate the browsersearch.json file for Fennec.
 
 This script follows these steps:
 
-1. Read the region.properties file in all the given source directories (see
-srcdir option). Merge all properties into a single dict accounting for the
-priority of source directories.
+1. Read all the given region.properties files (see inputs and --fallback
+options). Merge all properties into a single dict accounting for the priority
+of inputs.
 
 2. Read the default search plugin from 'browser.search.defaultenginename'.
 
 3. Read the list of search plugins from the 'browser.search.order.INDEX'
 properties with values identifying particular search plugins by name.
 
 4. Read each region-specific default search plugin from each property named like
 'browser.search.defaultenginename.REGION'.
@@ -33,62 +33,77 @@ e.g. raw/browsersearch.json, raw-pt-rBR/
 from __future__ import (
     absolute_import,
     print_function,
     unicode_literals,
 )
 
 import argparse
 import codecs
+import errno
 import json
 import sys
 import os
 
 from mozbuild.dotproperties import (
     DotProperties,
 )
 from mozbuild.util import (
     FileAvoidWrite,
 )
 import mozpack.path as mozpath
 
 
-def merge_properties(filename, srcdirs):
-    """Merges properties from the given file in the given source directories."""
+def merge_properties(paths):
+    """Merges properties from the given paths."""
     properties = DotProperties()
-    for srcdir in srcdirs:
-        path = mozpath.join(srcdir, filename)
+    for path in paths:
         try:
             properties.update(path)
-        except IOError:
-            # Ignore non-existing files
-            continue
+        except IOError as e:
+            if e.errno == errno.ENOENT:
+                # Ignore non-existant files.
+                continue
     return properties
 
 
-def main(args):
+def main(output, *args, **kwargs):
     parser = argparse.ArgumentParser()
     parser.add_argument('--verbose', '-v', default=False, action='store_true',
                         help='be verbose')
     parser.add_argument('--silent', '-s', default=False, action='store_true',
                         help='be silent')
-    parser.add_argument('--srcdir', metavar='SRCDIR',
-                        action='append', required=True,
-                        help='directories to read inputs from, in order of priority')
-    parser.add_argument('output', metavar='OUTPUT',
-                        help='output')
+    parser.add_argument('inputs', metavar='INPUT', nargs='*',
+                        help='inputs, in order of priority')
+    # This awkward "extra input" is an expedient work-around for an issue with
+    # the build system.  It allows to specify the in-tree unlocalized version
+    # of a resource where a regular input will always be the localized version.
+    parser.add_argument('--fallback',
+                        required=True,
+                        help='fallback input')
     opts = parser.parse_args(args)
 
-    # Use reversed order so that the first srcdir has higher priority to override keys.
-    properties = merge_properties('region.properties', reversed(opts.srcdir))
+    # Ensure the fallback is valid.
+    if not os.path.isfile(opts.fallback):
+        print('Fallback path {fallback} is not a file!'.format(fallback=opts.fallback))
+        return 1
+
+    # Use reversed order so that the first input has higher priority to override keys.
+    sources = [opts.fallback] + list(reversed(opts.inputs))
+    properties = merge_properties(sources)
 
     # Default, not region-specific.
     default = properties.get('browser.search.defaultenginename')
     engines = properties.get_list('browser.search.order')
 
+    # We must define at least one engine -- that's what the fallback is for.
+    if not engines:
+        print('No engines defined: searched in {}!'.format(sources))
+        return 1
+
     writer = codecs.getwriter('utf-8')(sys.stdout)
     if opts.verbose:
         print('Read {len} engines: {engines}'.format(len=len(engines), engines=engines), file=writer)
         print("Default engine is '{default}'.".format(default=default), file=writer)
 
     browsersearch = {}
     browsersearch['default'] = default
     browsersearch['engines'] = engines
@@ -107,25 +122,22 @@ def main(args):
             print("Region '{region}': Default engine is '{region_default}'.".format(
                 region=region, region_default=region_default), file=writer)
 
         browsersearch['regions'][region] = {
             'default': region_default,
             'engines': region_engines,
         }
 
-    # FileAvoidWrite creates its parent directories.
-    output = os.path.abspath(opts.output)
-    fh = FileAvoidWrite(output)
-    json.dump(browsersearch, fh)
-    existed, updated = fh.close()
+    json.dump(browsersearch, output)
+    existed, updated = output.close()  # It's safe to close a FileAvoidWrite multiple times.
 
     if not opts.silent:
         if updated:
-            print('{output} updated'.format(output=output))
+            print('{output} updated'.format(output=os.path.abspath(output.name)))
         else:
-            print('{output} already up-to-date'.format(output=output))
+            print('{output} already up-to-date'.format(output=os.path.abspath(output.name)))
 
-    return 0
+    return set([opts.fallback])
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv[1:]))

rename from python/mozbuild/mozbuild/action/generate_suggestedsites.py
rename to mobile/android/base/locales/generate_suggestedsites.py
--- a/python/mozbuild/mozbuild/action/generate_suggestedsites.py
+++ b/mobile/android/base/locales/generate_suggestedsites.py
@@ -2,19 +2,19 @@
 # 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/.
 
 ''' Script to generate the suggestedsites.json file for Fennec.
 
 This script follows these steps:
 
-1. Read the region.properties file in all the given source directories
-(see srcdir option). Merge all properties into a single dict accounting for
-the priority of source directories.
+1. Read all the given region.properties files (see inputs and --fallback
+options). Merge all properties into a single dict accounting for the priority
+of inputs.
 
 2. Read the list of sites from the list 'browser.suggestedsites.list.INDEX' and
 'browser.suggestedsites.restricted.list.INDEX' properties with value of these keys
 being an identifier for each suggested site e.g. browser.suggestedsites.list.0=mozilla,
 browser.suggestedsites.list.1=fxmarketplace.
 
 3. For each site identifier defined by the list keys, look for matching branches
 containing the respective properties i.e. url, title, etc. For example,
@@ -25,66 +25,76 @@ 4. Generate a JSON representation of eac
 write the result to suggestedsites.json on the locale-specific raw resource
 directory e.g. raw/suggestedsites.json, raw-pt-rBR/suggestedsites.json.
 '''
 
 from __future__ import absolute_import, print_function
 
 import argparse
 import copy
+import errno
 import json
 import sys
 import os
 
 from mozbuild.dotproperties import (
     DotProperties,
 )
 from mozbuild.util import (
     FileAvoidWrite,
 )
 from mozpack.files import (
     FileFinder,
 )
 import mozpack.path as mozpath
 
 
-def merge_properties(filename, srcdirs):
-    """Merges properties from the given file in the given source directories."""
+def merge_properties(paths):
+    """Merges properties from the given paths."""
     properties = DotProperties()
-    for srcdir in srcdirs:
-        path = mozpath.join(srcdir, filename)
+    for path in paths:
         try:
             properties.update(path)
-        except IOError:
-            # Ignore non-existing files
-            continue
+        except IOError as e:
+            if e.errno == errno.ENOENT:
+                # Ignore non-existant files.
+                continue
     return properties
 
 
-def main(args):
+def main(output, *args, **kwargs):
     parser = argparse.ArgumentParser()
     parser.add_argument('--verbose', '-v', default=False, action='store_true',
                         help='be verbose')
     parser.add_argument('--silent', '-s', default=False, action='store_true',
                         help='be silent')
     parser.add_argument('--android-package-name', metavar='NAME',
                         required=True,
                         help='Android package name')
     parser.add_argument('--resources', metavar='RESOURCES',
                         default=None,
                         help='optional Android resource directory to find drawables in')
-    parser.add_argument('--srcdir', metavar='SRCDIR',
-                        action='append', required=True,
-                        help='directories to read inputs from, in order of priority')
-    parser.add_argument('output', metavar='OUTPUT',
-                        help='output')
+    parser.add_argument('inputs', metavar='INPUT', nargs='*',
+                        help='inputs, in order of priority')
+    # This awkward "extra input" is an expedient work-around for an issue with
+    # the build system.  It allows to specify the in-tree unlocalized version
+    # of a resource where a regular input will always be the localized version.
+    parser.add_argument('--fallback',
+                        required=True,
+                        help='fallback input')
     opts = parser.parse_args(args)
 
+    # Ensure the fallback is valid.
+    if not os.path.isfile(opts.fallback):
+        print('Fallback path {fallback} is not a file!'.format(fallback=opts.fallback))
+        return 1
+
     # Use reversed order so that the first srcdir has higher priority to override keys.
-    properties = merge_properties('region.properties', reversed(opts.srcdir))
+    sources = [opts.fallback] + list(reversed(opts.inputs))
+    properties = merge_properties(sources)
 
     # Keep these two in sync.
     image_url_template = 'android.resource://%s/drawable/suggestedsites_{name}' % opts.android_package_name
     drawables_template = 'drawable*/suggestedsites_{name}.*'
 
     # Load properties corresponding to each site name and define their
     # respective image URL.
     sites = []
@@ -122,26 +132,27 @@ def main(args):
         print('Reading {len} suggested site lists: {lists}'.format(len=len(lists), lists=[list_name for list_name, _ in lists]))
 
     for (list_name, list_item_defaults) in lists:
         names = properties.get_list(list_name)
         if opts.verbose:
             print('Reading {len} suggested sites from {list}: {names}'.format(len=len(names), list=list_name, names=names))
         add_names(names, list_item_defaults)
 
+    # We must define at least one site -- that's what the fallback is for.
+    if not sites:
+        print('No sites defined: searched in {}!'.format(sources))
+        return 1
 
-    # FileAvoidWrite creates its parent directories.
-    output = os.path.abspath(opts.output)
-    fh = FileAvoidWrite(output)
-    json.dump(sites, fh)
-    existed, updated = fh.close()
+    json.dump(sites, output)
+    existed, updated = output.close()  # It's safe to close a FileAvoidWrite multiple times.
 
     if not opts.silent:
         if updated:
-            print('{output} updated'.format(output=output))
+            print('{output} updated'.format(output=os.path.abspath(output.name)))
         else:
-            print('{output} already up-to-date'.format(output=output))
+            print('{output} already up-to-date'.format(output=os.path.abspath(output.name)))
 
-    return 0
+    return set([opts.fallback])
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv[1:]))

--- a/mobile/android/base/locales/moz.build
+++ b/mobile/android/base/locales/moz.build
@@ -1,5 +1,37 @@
 # -*- 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/.
+
+LOCALIZED_GENERATED_FILES += ['../res/raw{AB_rCD}/browsersearch.json']
+browsersearch = LOCALIZED_GENERATED_FILES['../res/raw{AB_rCD}/browsersearch.json']
+browsersearch.script = 'generate_browsersearch.py'
+browsersearch.inputs = [
+    # The `locales/en-US/` in this path will be rewritten to the
+    # locale-specific path.
+    '/mobile/locales/en-US/chrome/region.properties',
+]
+browsersearch.flags += ['--verbose']
+browsersearch.flags += [
+    '--fallback',
+    # The `locales/en-US` in this path will not be rewritten.
+    TOPSRCDIR + '/mobile/locales/en-US/chrome/region.properties'
+]
+
+LOCALIZED_GENERATED_FILES += ['../res/raw{AB_rCD}/suggestedsites.json']
+suggestedsites = LOCALIZED_GENERATED_FILES['../res/raw{AB_rCD}/suggestedsites.json']
+suggestedsites.script = 'generate_suggestedsites.py'
+suggestedsites.inputs = [
+    # The `locales/en-US/` in this path will be rewritten to the
+    # locale-specific path.
+    '/mobile/locales/en-US/chrome/region.properties',
+]
+suggestedsites.flags += ['--verbose']
+suggestedsites.flags += ['--android-package-name', CONFIG['ANDROID_PACKAGE_NAME']]
+suggestedsites.flags += ['--resources', TOPSRCDIR + '/mobile/android/app/src/photon/res']
+suggestedsites.flags += [
+    '--fallback',
+    # The `locales/en-US` in this path will not be rewritten.
+    TOPSRCDIR + '/mobile/locales/en-US/chrome/region.properties'
+]

--- a/python/mozbuild/mozbuild/backend/recursivemake.py
+++ b/python/mozbuild/mozbuild/backend/recursivemake.py
@@ -522,36 +522,64 @@ class RecursiveMakeBackend(CommonBackend
         elif isinstance(obj, GeneratedFile):
             if obj.required_for_compile:
                 tier = 'export'
             elif obj.localized:
                 tier = 'libs'
             else:
                 tier = 'misc'
             self._no_skip[tier].add(backend_file.relobjdir)
+
+            # Localized generated files can use {AB_CD} and {AB_rCD} in their
+            # output paths.
+            if obj.localized:
+                substs = {'AB_CD': '$(AB_CD)', 'AB_rCD': '$(AB_rCD)'}
+            else:
+                substs = {}
+            substituted = []
+
+            # It would be nice to only write AB_rCD once per backend.mk, but it
+            # does not harm to write it multiple times, and it's awkward to
+            # track flags across multiple GeneratedFile instances.
+            needs_AB_rCD = False
+            for o in obj.outputs:
+                needs_AB_rCD = needs_AB_rCD or ('AB_rCD' in o)
+                try:
+                    substituted.append(o.format(**substs))
+                except KeyError as e:
+                    raise ValueError('%s not in %s is not a valid substitution in %s'
+                                     % (e.args[0], ', '.join(sorted(substs.keys())), o))
+            obj.outputs = tuple(substituted)
+
             first_output = obj.outputs[0]
             dep_file = "%s.pp" % first_output
 
             if obj.inputs:
                 if obj.localized:
                     # Localized generated files can have locale-specific inputs, which are
-                    # indicated by paths starting with `en-US/`.
+                    # indicated by paths starting with `en-US/` or containing `/locales/en-US/`.
                     def srcpath(p):
-                        bits = p.split('en-US/', 1)
-                        if len(bits) == 2:
-                            e, f = bits
+                        if '/locales/en-US' in p:
+                            e, f = p.split('/locales/en-US/', 1)
+                            assert(f)
+                            return '$(call MERGE_RELATIVE_FILE,%s,/locales/%s)' % (f, e)
+                        elif p.startswith('en-US/'):
+                            e, f = p.split('en-US/', 1)
                             assert(not e)
                             return '$(call MERGE_FILE,%s)' % f
                         return self._pretty_path(p, backend_file)
                     inputs = [srcpath(f) for f in obj.inputs]
                 else:
                     inputs = [self._pretty_path(f, backend_file) for f in obj.inputs]
             else:
                 inputs = []
 
+            if needs_AB_rCD:
+                backend_file.write('include $(topsrcdir)/config/AB_rCD.mk\n')
+
             # If we're doing this during export that means we need it during
             # compile, but if we have an artifact build we don't run compile,
             # so we can skip it altogether or let the rule run as the result of
             # something depending on it.
             if tier != 'export' or not self.environment.is_artifact_build:
                 backend_file.write('%s:: %s\n' % (tier, first_output))
             for output in obj.outputs:
                 if output != first_output:

--- a/python/mozbuild/mozbuild/frontend/emitter.py
+++ b/python/mozbuild/mozbuild/frontend/emitter.py
@@ -1234,20 +1234,27 @@ class TreeMetadataEmitter(LoggingMixin):
                                 'OBJDIR_PP_FILES',
                                 'LOCALIZED_PP_FILES') and
                         not isinstance(f, SourcePath)):
                         raise SandboxValidationError(
                                 ('Only source directory paths allowed in ' +
                                  '%s: %s')
                                 % (var, f,), context)
                     if var.startswith('LOCALIZED_'):
-                        if isinstance(f, SourcePath) and not f.startswith('en-US/'):
-                            raise SandboxValidationError(
-                                    '%s paths must start with `en-US/`: %s'
-                                    % (var, f,), context)
+                        if isinstance(f, SourcePath):
+                            if f.startswith('en-US/'):
+                                pass
+                            elif '/locales/en-US/' in f:
+                                pass
+                            else:
+                                raise SandboxValidationError(
+                                        '%s paths must start with `en-US/` or '
+                                        'contain `/locales/en-US/`: %s'
+                                        % (var, f,), context)
+
                     if not isinstance(f, ObjDirPath):
                         path = f.full_path
                         if '*' not in path and not os.path.exists(path):
                             raise SandboxValidationError(
                                 'File listed in %s does not exist: %s'
                                 % (var, path), context)
                     else:
                         # TODO: Bug 1254682 - The '/' check is to allow

new file mode 100644
--- /dev/null
+++ b/python/mozbuild/mozbuild/test/backend/data/localized-files-AB_CD/en-US/abc/test.abc
@@ -0,0 +1,1 @@
+test

copy from python/mozbuild/mozbuild/test/backend/data/localized-files/en-US/bar.ini
copy to python/mozbuild/mozbuild/test/backend/data/localized-files-AB_CD/en-US/bar.ini

copy from python/mozbuild/mozbuild/test/backend/data/localized-files/en-US/foo.js
copy to python/mozbuild/mozbuild/test/backend/data/localized-files-AB_CD/en-US/foo.js

copy from python/mozbuild/mozbuild/test/backend/data/localized-files/moz.build
copy to python/mozbuild/mozbuild/test/backend/data/localized-files-AB_CD/moz.build
--- a/python/mozbuild/mozbuild/test/backend/data/localized-files/moz.build
+++ b/python/mozbuild/mozbuild/test/backend/data/localized-files-AB_CD/moz.build
@@ -1,9 +1,12 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
-LOCALIZED_FILES += [
+LOCALIZED_FILES.x['{AB_CD}'] += [
     'en-US/abc/*.abc',
+]
+
+LOCALIZED_FILES.y['raw{AB_rCD}'] += [
     'en-US/bar.ini',
     'en-US/foo.js',
 ]

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/en-US/localized-input
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/en-US/localized-input

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/foo-data
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/foo-data

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/generate-foo.py
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/generate-foo.py

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/en-US/localized-input
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/inner/locales/en-US/localized-input

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/moz.build
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/moz.build
--- a/python/mozbuild/mozbuild/test/backend/data/localized-generated-files/moz.build
+++ b/python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/moz.build
@@ -1,15 +1,21 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
-LOCALIZED_GENERATED_FILES += [ 'foo.xyz' ]
+LOCALIZED_GENERATED_FILES += [ 'foo{AB_CD}.xyz' ]
 
-foo = LOCALIZED_GENERATED_FILES['foo.xyz']
+foo = LOCALIZED_GENERATED_FILES['foo{AB_CD}.xyz']
 foo.script = 'generate-foo.py'
 foo.inputs = [
     'en-US/localized-input',
     'non-localized-input',
 ]
 
-# Also check that using it in LOCALIZED_FILES does the right thing.
-LOCALIZED_FILES += [ '!foo.xyz' ]
+LOCALIZED_GENERATED_FILES += [ 'bar{AB_rCD}.xyz' ]
+
+bar = LOCALIZED_GENERATED_FILES['bar{AB_rCD}.xyz']
+bar.script = 'generate-foo.py'
+bar.inputs = [
+    'inner/locales/en-US/localized-input',
+    'non-localized-input',
+]

copy from python/mozbuild/mozbuild/test/backend/data/localized-generated-files/non-localized-input
copy to python/mozbuild/mozbuild/test/backend/data/localized-generated-files-AB_CD/non-localized-input

--- a/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
+++ b/python/mozbuild/mozbuild/test/backend/test_recursivemake.py
@@ -437,16 +437,44 @@ class TestRecursiveMakeBackend(BackendTe
             'LOCALIZED_FILES_0_DEST = $(FINAL_TARGET)/',
             'LOCALIZED_FILES_0_TARGET := libs',
             'INSTALL_TARGETS += LOCALIZED_FILES_0',
         ]
 
         self.maxDiff = None
         self.assertEqual(lines, expected)
 
+    def test_localized_generated_files_AB_CD(self):
+        """Ensure LOCALIZED_GENERATED_FILES is handled properly
+        when {AB_CD} and {AB_rCD} are used."""
+        env = self._consume('localized-generated-files-AB_CD', RecursiveMakeBackend)
+
+        backend_path = mozpath.join(env.topobjdir, 'backend.mk')
+        lines = [l.strip() for l in open(backend_path, 'rt').readlines()[2:]]
+
+        expected = [
+            'libs:: foo$(AB_CD).xyz',
+            'GARBAGE += foo$(AB_CD).xyz',
+            'EXTRA_MDDEPEND_FILES += foo$(AB_CD).xyz.pp',
+            'foo$(AB_CD).xyz: %s/generate-foo.py $(call MERGE_FILE,localized-input) $(srcdir)/non-localized-input $(if $(IS_LANGUAGE_REPACK),FORCE)' % env.topsrcdir,
+            '$(REPORT_BUILD)',
+            '$(call py_action,file_generate,--locale=$(AB_CD) %s/generate-foo.py main foo$(AB_CD).xyz $(MDDEPDIR)/foo$(AB_CD).xyz.pp $(call MERGE_FILE,localized-input) $(srcdir)/non-localized-input)' % env.topsrcdir,
+            '',
+            'include $(topsrcdir)/config/AB_rCD.mk',
+            'GARBAGE += bar$(AB_rCD).xyz',
+            'EXTRA_MDDEPEND_FILES += bar$(AB_rCD).xyz.pp',
+            'bar$(AB_rCD).xyz: %s/generate-foo.py $(call MERGE_RELATIVE_FILE,localized-input,/locales/inner) $(srcdir)/non-localized-input $(if $(IS_LANGUAGE_REPACK),FORCE)' % env.topsrcdir,
+            '$(REPORT_BUILD)',
+            '$(call py_action,file_generate,--locale=$(AB_CD) %s/generate-foo.py main bar$(AB_rCD).xyz $(MDDEPDIR)/bar$(AB_rCD).xyz.pp $(call MERGE_RELATIVE_FILE,localized-input,/locales/inner) $(srcdir)/non-localized-input)' % env.topsrcdir,
+            '',
+        ]
+
+        self.maxDiff = None
+        self.assertEqual(lines, expected)
+
     def test_exports_generated(self):
         """Ensure EXPORTS that are listed in GENERATED_FILES
         are handled properly."""
         env = self._consume('exports-generated', RecursiveMakeBackend)
 
         # EXPORTS files should appear in the dist_include install manifest.
         m = InstallManifest(path=mozpath.join(env.topobjdir,
             '_build_manifests', 'install', 'dist_include'))

new file mode 100644

--- a/python/mozbuild/mozbuild/test/frontend/data/localized-files-no-en-us/moz.build
+++ b/python/mozbuild/mozbuild/test/frontend/data/localized-files-no-en-us/moz.build
@@ -1,8 +1,9 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # Any copyright is dedicated to the Public Domain.
 # http://creativecommons.org/publicdomain/zero/1.0/
 
 LOCALIZED_FILES.foo += [
     'en-US/bar.ini',
     'foo.js',
+    'inner/locales/en-US/bar.ini',
 ]

--- a/python/mozbuild/mozbuild/test/frontend/test_emitter.py
+++ b/python/mozbuild/mozbuild/test/frontend/test_emitter.py
@@ -1367,20 +1367,20 @@ class TestEmitterBasic(unittest.TestCase
             self.assertEqual(len(files), 3)
 
             expected = {'en-US/bar.ini', 'en-US/code/*.js', 'en-US/foo.js'}
             for f in files:
                 self.assertTrue(unicode(f) in expected)
 
     def test_localized_files_no_en_us(self):
         """Test that LOCALIZED_FILES errors if a path does not start with
-        `en-US/`."""
+        `en-US/` or contain `/locales/en-US/`."""
         reader = self.reader('localized-files-no-en-us')
         with self.assertRaisesRegexp(SandboxValidationError,
-             'LOCALIZED_FILES paths must start with `en-US/`:'):
+             'LOCALIZED_FILES paths must start with `en-US/` or contain `/locales/en-US/`: foo.js'):
             objs = self.read_topsrcdir(reader)
 
     def test_localized_pp_files(self):
         """Test that LOCALIZED_PP_FILES works properly."""
         reader = self.reader('localized-pp-files')
         objs = self.read_topsrcdir(reader)
 
         self.assertEqual(len(objs), 1)