--- a/mobile/android/base/AdjustConstants.java.in
+++ b/mobile/android/base/AdjustConstants.java.in
@@ -1,10 +1,9 @@
 //#filter substitution
-//#include @OBJDIR@/adjust_sdk_app_token
 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
  * 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/. */
 
 package org.mozilla.gecko;
 
 import org.mozilla.gecko.adjust.AdjustHelperInterface;

--- a/mobile/android/base/AppConstants.java.in
+++ b/mobile/android/base/AppConstants.java.in
@@ -88,18 +88,17 @@ public class AppConstants {
     // GRE_BUILDID is exactly the same as MOZ_APP_BUILDID unless you're running
     // on XULRunner, which is never the case on Android.
     public static final String MOZ_APP_BUILDID = "@MOZ_BUILDID@";
     public static final String MOZ_APP_ID = "@MOZ_APP_ID@";
     public static final String MOZ_APP_NAME = "@MOZ_APP_NAME@";
     public static final String MOZ_APP_VENDOR = "@MOZ_APP_VENDOR@";
     public static final String MOZ_APP_VERSION = "@MOZ_APP_VERSION@";
     public static final String MOZ_APP_DISPLAYNAME = "@MOZ_APP_DISPLAYNAME@";
-    // MOZ_APP_UA_NAME is already quoted when it gets substituted, like MOZILLA_VERSION.
-    public static final String MOZ_APP_UA_NAME = @MOZ_APP_UA_NAME@;
+    public static final String MOZ_APP_UA_NAME = "@MOZ_APP_UA_NAME@";
 
     // MOZILLA_VERSION is already quoted when it gets substituted in. If we
     // add additional quotes we end up with ""x.y"", which is a syntax error.
     public static final String MOZILLA_VERSION = @MOZILLA_VERSION@;
 
     public static final String MOZ_MOZILLA_API_KEY = "@MOZ_MOZILLA_API_KEY@";
     public static final boolean MOZ_STUMBLER_BUILD_TIME_ENABLED =
 //#ifdef MOZ_ANDROID_MLS_STUMBLER
@@ -121,17 +120,17 @@ public class AppConstants {
 //#else
     null;
 //#endif
 
     public static final String MOZ_CHILD_PROCESS_NAME = "@MOZ_CHILD_PROCESS_NAME@";
     public static final String MOZ_UPDATE_CHANNEL = "@MOZ_UPDATE_CHANNEL@";
     public static final String OMNIJAR_NAME = "@OMNIJAR_NAME@";
     public static final String OS_TARGET = "@OS_TARGET@";
-    public static final String TARGET_XPCOM_ABI = @TARGET_XPCOM_ABI@;
+    public static final String TARGET_XPCOM_ABI = "@TARGET_XPCOM_ABI@";
 
     public static final String USER_AGENT_BOT_LIKE = "Redirector/" + AppConstants.MOZ_APP_VERSION +
         " (Android; rv:" + AppConstants.MOZ_APP_VERSION + ")";
 
     public static final String USER_AGENT_FENNEC_MOBILE = "Mozilla/5.0 (Android " +
         Build.VERSION.RELEASE + "; Mobile; rv:" +
         AppConstants.MOZ_APP_VERSION + ") Gecko/" +
         AppConstants.MOZ_APP_VERSION + " Firefox/" +

--- a/mobile/android/base/Makefile.in
+++ b/mobile/android/base/Makefile.in
@@ -320,34 +320,16 @@ GeneratedJNIWrappers.cpp: $(ANNOTATION_P
 
 # This annotation processing step also generates
 # FennecJNIWrappers.h and FennecJNINatives.h
 FennecJNIWrappers.cpp: $(ANNOTATION_PROCESSOR_JAR_FILES) $(FENNEC_JARS)
 	$(JAVA) -classpath $(all_jars_classpath):$(JAVA_BOOTCLASSPATH):$(JAVA_CLASSPATH):$(ANNOTATION_PROCESSOR_JAR_FILES) \
 		org.mozilla.gecko.annotationProcessors.AnnotationProcessor \
 		Fennec $(FENNEC_JARS)
 
-# Certain source files need to be preprocessed.  This special rule
-# generates these files into generated/org/mozilla/gecko for
-# consumption by the build system and IDEs.
-
-# The list in moz.build looks like
-# 'preprocessed/org/mozilla/gecko/AppConstants.java'.  The list in
-# constants_PP_JAVAFILES looks like
-# 'generated/preprocessed/org/mozilla/gecko/AppConstants.java'.  We
-# need to write AppConstants.java.in to
-# generated/preprocessed/org/mozilla/gecko.
-preprocessed := $(addsuffix .in,$(subst generated/preprocessed/org/mozilla/gecko/,,$(filter generated/preprocessed/org/mozilla/gecko/%,$(constants_PP_JAVAFILES))))
-
-preprocessed_PATH := generated/preprocessed/org/mozilla/gecko
-preprocessed_KEEP_PATH := 1
-preprocessed_FLAGS := --marker='//\\\#'
-
-PP_TARGETS += preprocessed
-
 include $(topsrcdir)/config/rules.mk
 
 not_android_res_files := \
   *.mkdir.done* \
   *.DS_Store* \
   *\#* \
   *.rej \
   *.orig \

deleted file mode 100644
--- a/mobile/android/base/adjust_sdk_app_token.in
+++ /dev/null
@@ -1,3 +0,0 @@
-//#ifdef MOZ_INSTALL_TRACKING
-//#define MOZ_INSTALL_TRACKING_ADJUST_SDK_APP_TOKEN @MOZ_ADJUST_SDK_KEY@
-//#endif

new file mode 100644
--- /dev/null
+++ b/mobile/android/base/generate_build_config.py
@@ -0,0 +1,116 @@
+#!/bin/python
+
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# 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/.
+
+'''
+Generate BuildConfig Java source files.
+
+BuildConfig files are the Gradle way of configuring Java values at build time.
+
+This is the moz.build equivalent of Gradle's `buildConfigField` (see
+http://google.github.io/android-gradle-dsl/current/com.android.build.gradle.internal.dsl.ProductFlavor.html#com.android.build.gradle.internal.dsl.ProductFlavor:buildConfigField(java.lang.String,%20java.lang.String,%20java.lang.String).
+This mechanism will be replaced with the Gradle native version as we
+transition to Gradle.
+'''
+
+from __future__ import (
+    print_function,
+    unicode_literals,
+)
+
+from collections import defaultdict
+import os
+import sys
+
+import buildconfig
+from mozbuild.preprocessor import Preprocessor
+
+
+def main(output_file, input_filename):
+    # input_filename is an absolute path, so there's no need to join with __DIR__.
+    pp = Preprocessor(defines=buildconfig.defines, marker='//#')
+
+    CONFIG = defaultdict(lambda: None)
+    CONFIG.update(buildconfig.substs)
+    DEFINES = {}
+
+    for var in ('MOZ_ANDROID_ACTIVITY_STREAM'
+                'MOZ_ANDROID_ANR_REPORTER',
+                'MOZ_ANDROID_BEAM',
+                'MOZ_ANDROID_CUSTOM_TABS',
+                'MOZ_ANDROID_DOWNLOADS_INTEGRATION',
+                'MOZ_ANDROID_DOWNLOAD_CONTENT_SERVICE',
+                'MOZ_ANDROID_EXCLUDE_FONTS',
+                'MOZ_ANDROID_GCM',
+                'MOZ_ANDROID_MLS_STUMBLER',
+                'MOZ_ANDROID_SEARCH_ACTIVITY',
+                'MOZ_DEBUG',
+                'MOZ_INSTALL_TRACKING',
+                'MOZ_LOCALE_SWITCHER',
+                'MOZ_NATIVE_DEVICES',
+                'MOZ_SWITCHBOARD'):
+        if CONFIG[var]:
+            DEFINES[var] = 1
+
+    for var in ('MOZ_ANDROID_GCM_SENDERID',
+                'MOZ_PKG_SPECIAL',
+                'MOZ_UPDATER'):
+        if CONFIG[var]:
+            DEFINES[var] = CONFIG[var]
+
+    for var in ('ANDROID_CPU_ARCH',
+                'ANDROID_PACKAGE_NAME',
+                'GRE_MILESTONE',
+                'MOZ_ANDROID_APPLICATION_CLASS',
+                'MOZ_ANDROID_BROWSER_INTENT_CLASS',
+                'MOZ_ANDROID_SEARCH_INTENT_CLASS',
+                'MOZ_APP_BASENAME',
+                'MOZ_APP_DISPLAYNAME',
+                'MOZ_APP_ID',
+                'MOZ_APP_NAME',
+                'MOZ_APP_UA_NAME',
+                'MOZ_APP_VENDOR',
+                'MOZ_APP_VERSION',
+                'MOZ_CHILD_PROCESS_NAME',
+                'MOZ_CRASHREPORTER',
+                'MOZ_MOZILLA_API_KEY',
+                'MOZ_UPDATE_CHANNEL',
+                'OMNIJAR_NAME',
+                'OS_TARGET',
+                'TARGET_XPCOM_ABI'):
+        DEFINES[var] = CONFIG[var]
+
+    # Mangle our package name to avoid Bug 750548.
+    DEFINES['MANGLED_ANDROID_PACKAGE_NAME'] = CONFIG['ANDROID_PACKAGE_NAME'].replace('fennec', 'f3nn3c')
+    DEFINES['MOZ_APP_ABI'] = CONFIG['TARGET_XPCOM_ABI']
+    if not CONFIG['COMPILE_ENVIRONMENT']:
+        # These should really come from the included binaries, but that's not easy.
+        DEFINES['MOZ_APP_ABI'] = 'arm-eabi-gcc3'
+        DEFINES['TARGET_XPCOM_ABI'] = 'arm-eabi-gcc3'
+
+    if '-march=armv7' in CONFIG['OS_CFLAGS']:
+        DEFINES['MOZ_MIN_CPU_VERSION'] = 7
+    else:
+        DEFINES['MOZ_MIN_CPU_VERSION'] = 5
+
+    # It's okay to use MOZ_ADJUST_SDK_KEY here because this doesn't
+    # leak the value to build logs.
+    if CONFIG['MOZ_INSTALL_TRACKING']:
+        DEFINES['MOZ_INSTALL_TRACKING_ADJUST_SDK_APP_TOKEN'] = CONFIG['MOZ_ADJUST_SDK_KEY']
+
+    # TODO: mark buildid.h as a dependency?  How about the buildconfig itself?
+    DEFINES['MOZ_BUILDID'] = open(os.path.join(buildconfig.topobjdir, 'buildid.h')).readline().split()[2]
+
+    pp.context.update(DEFINES)
+
+    with open(input_filename, 'rU') as input:
+        pp.processFile(input=input, output=output_file)
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.stdout, *sys.argv[1:]))

--- a/mobile/android/base/moz.build
+++ b/mobile/android/base/moz.build
@@ -1,17 +1,26 @@
 # -*- 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/.
 
 DIRS += ['locales']
 
-CONFIGURE_SUBST_FILES += ['adjust_sdk_app_token']
+GENERATED_FILES += [
+    'generated/preprocessed/org/mozilla/gecko/AdjustConstants.java',
+    'generated/preprocessed/org/mozilla/gecko/AppConstants.java',
+]
+x = GENERATED_FILES['generated/preprocessed/org/mozilla/gecko/AdjustConstants.java']
+x.script = 'generate_build_config.py'
+x.inputs += ['AdjustConstants.java.in']
+y = GENERATED_FILES['generated/preprocessed/org/mozilla/gecko/AppConstants.java']
+y.script = 'generate_build_config.py'
+y.inputs += ['AppConstants.java.in']
 
 include('android-services.mozbuild')
 
 geckoview_source_dir = TOPSRCDIR + '/mobile/android/geckoview/src/main/'
 geckoview_thirdparty_source_dir = TOPSRCDIR + '/mobile/android/geckoview/src/thirdparty/'
 thirdparty_source_dir = TOPSRCDIR + '/mobile/android/thirdparty/'
 
 constants_jar = add_java_jar('constants')