--- a/b2g/moz.configure
+++ b/b2g/moz.configure
@@ -6,16 +6,18 @@
 
 option('--with-gonk', nargs=1, help='Path to the gonk base directory')
 
 @depends_if('--with-gonk')
 def gonkdir(value):
     return value[0]
 
 add_old_configure_assignment('gonkdir', gonkdir)
+set_config('ANDROID_NDK',
+           depends_if(gonkdir)(lambda x: os.path.join(x, 'ndk')))
 
 @depends_if('--with-gonk')
 def gonk_toolkit(_):
     return 'cairo-gonk'
 
 imply_option('--enable-default-toolkit', gonk_toolkit)
 
 

--- a/build/autoconf/android.m4
+++ b/build/autoconf/android.m4
@@ -1,30 +1,15 @@
 dnl This Source Code Form is subject to the terms of the Mozilla Public
 dnl License, v. 2.0. If a copy of the MPL was not distributed with this
 dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 AC_DEFUN([MOZ_ANDROID_NDK],
 [
 
-MOZ_ARG_WITH_STRING(android-ndk,
-[  --with-android-ndk=DIR
-                          location where the Android NDK can be found],
-    android_ndk=$withval)
-
-MOZ_ARG_WITH_STRING(android-toolchain,
-[  --with-android-toolchain=DIR
-                          location of the Android toolchain],
-    android_toolchain=$withval)
-
-MOZ_ARG_WITH_STRING(android-gnu-compiler-version,
-[  --with-android-gnu-compiler-version=VER
-                          gnu compiler version to use],
-    android_gnu_compiler_version=$withval)
-
 MOZ_ARG_WITH_STRING(android-cxx-stl,
 [  --with-android-cxx-stl=VALUE
                           use the specified C++ STL (stlport, libstdc++, libc++)],
     android_cxx_stl=$withval,
     android_cxx_stl=mozstlport)
 
 define([MIN_ANDROID_VERSION], [9])
 android_version=MIN_ANDROID_VERSION
@@ -34,86 +19,17 @@ MOZ_ARG_WITH_STRING(android-version,
                           android platform version, default] MIN_ANDROID_VERSION,
     android_version=$withval)
 
 if test $android_version -lt MIN_ANDROID_VERSION ; then
     AC_MSG_ERROR([--with-android-version must be at least MIN_ANDROID_VERSION.])
 fi
 
 case "$target" in
-arm-*linux*-android*|*-linuxandroid*)
-    android_tool_prefix="arm-linux-androideabi"
-    ;;
-i?86-*android*)
-    android_tool_prefix="i686-linux-android"
-    ;;
-mipsel-*android*)
-    android_tool_prefix="mipsel-linux-android"
-    ;;
-*)
-    android_tool_prefix="$target_os"
-    ;;
-esac
-
-case "$target" in
 *-android*|*-linuxandroid*)
-    if test -z "$android_ndk" ; then
-        AC_MSG_ERROR([You must specify --with-android-ndk=/path/to/ndk when targeting Android.])
-    fi
-
-    if test -z "$android_toolchain" ; then
-        AC_MSG_CHECKING([for android toolchain directory])
-
-        kernel_name=`uname -s | tr "[[:upper:]]" "[[:lower:]]"`
-
-        for version in $android_gnu_compiler_version 4.9 4.8 4.7; do
-            case "$target_cpu" in
-            arm)
-                target_name=arm-linux-androideabi-$version
-                ;;
-            i?86)
-                target_name=x86-$version
-                ;;
-            mipsel)
-                target_name=mipsel-linux-android-$version
-                ;;
-            *)
-                AC_MSG_ERROR([target cpu is not supported])
-                ;;
-            esac
-            case "$host_cpu" in
-            i*86)
-                android_toolchain="$android_ndk"/toolchains/$target_name/prebuilt/$kernel_name-x86
-                ;;
-            x86_64)
-                android_toolchain="$android_ndk"/toolchains/$target_name/prebuilt/$kernel_name-x86_64
-                if ! test -d "$android_toolchain" ; then
-                    android_toolchain="$android_ndk"/toolchains/$target_name/prebuilt/$kernel_name-x86
-                fi
-                ;;
-            *)
-                AC_MSG_ERROR([No known toolchain for your host cpu])
-                ;;
-            esac
-            if test -d "$android_toolchain" ; then
-                android_gnu_compiler_version=$version
-                break
-            elif test -n "$android_gnu_compiler_version" ; then
-                AC_MSG_ERROR([not found. Your --with-android-gnu-compiler-version may be wrong.])
-            fi
-        done
-
-        if test -z "$android_gnu_compiler_version" ; then
-            AC_MSG_ERROR([not found. You have to specify --with-android-toolchain=/path/to/ndk/toolchain.])
-        else
-            AC_MSG_RESULT([$android_toolchain])
-        fi
-        NSPR_CONFIGURE_ARGS="$NSPR_CONFIGURE_ARGS --with-android-toolchain=$android_toolchain"
-    fi
-
     NSPR_CONFIGURE_ARGS="$NSPR_CONFIGURE_ARGS --with-android-version=$android_version"
 
     AC_MSG_CHECKING([for android platform directory])
 
     case "$target_cpu" in
     arm)
         target_name=arm
         ;;
@@ -128,35 +44,29 @@ case "$target" in
     android_platform="$android_ndk"/platforms/android-"$android_version"/arch-"$target_name"
 
     if test -d "$android_platform" ; then
         AC_MSG_RESULT([$android_platform])
     else
         AC_MSG_ERROR([not found. Please check your NDK. With the current configuration, it should be in $android_platform])
     fi
 
-    TOOLCHAIN_PREFIX="$android_toolchain/bin/$android_tool_prefix-"
-
     CPPFLAGS="-idirafter $android_platform/usr/include $CPPFLAGS"
     CFLAGS="-mandroid -fno-short-enums -fno-exceptions $CFLAGS"
     CXXFLAGS="-mandroid -fno-short-enums -fno-exceptions $CXXFLAGS"
     ASFLAGS="-idirafter $android_platform/usr/include -DANDROID $ASFLAGS"
 
     dnl Add -llog by default, since we use it all over the place.
     dnl Add --allow-shlib-undefined, because libGLESv2 links to an
     dnl undefined symbol (present on the hardware, just not in the
     dnl NDK.)
     LDFLAGS="-mandroid -L$android_platform/usr/lib -Wl,-rpath-link=$android_platform/usr/lib --sysroot=$android_platform -llog -Wl,--allow-shlib-undefined $LDFLAGS"
-    ANDROID_NDK="${android_ndk}"
-    ANDROID_TOOLCHAIN="${android_toolchain}"
     ANDROID_PLATFORM="${android_platform}"
 
     AC_DEFINE(ANDROID)
-    AC_SUBST(ANDROID_NDK)
-    AC_SUBST(ANDROID_TOOLCHAIN)
     AC_SUBST(ANDROID_PLATFORM)
 
     ;;
 esac
 
 ])
 
 AC_DEFUN([MOZ_ANDROID_CPU_ARCH],

--- a/build/gyp.mozbuild
+++ b/build/gyp.mozbuild
@@ -84,17 +84,17 @@ elif os == 'Android':
         gyp_vars['moz_widget_toolkit_gonk'] = 1
         gyp_vars['opus_complexity'] = 1
         if int(CONFIG['ANDROID_VERSION']) >= 18:
           gyp_vars['moz_webrtc_omx'] = 1
     else:
         gyp_vars.update(
             gtest_target_type='executable',
             moz_webrtc_mediacodec=1,
-            android_toolchain=CONFIG['ANDROID_TOOLCHAIN'],
+            android_toolchain=CONFIG.get('ANDROID_TOOLCHAIN', ''),
         )
 
 flavors = {
     'WINNT': 'win',
     'Android': 'linux' if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gonk' else 'android',
     'Linux': 'linux',
     'Darwin': 'mac' if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa' else 'ios',
     'SunOS': 'solaris',

new file mode 100644
--- /dev/null
+++ b/build/moz.configure/android-ndk.configure
@@ -0,0 +1,77 @@
+# -*- 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_option('--with-android-ndk', nargs=1,
+          help='location where the Android NDK can be found')
+
+js_option('--with-android-toolchain', nargs=1,
+          help='location of the Android toolchain')
+
+js_option('--with-android-gnu-compiler-version', nargs=1,
+          help='GNU compiler version to use')
+
+@depends('--with-android-ndk', build_project)
+def ndk(value, build_project):
+    if build_project == 'mobile/android' and not value:
+        die('You must specify --with-android-ndk=/path/to/ndk when '
+            'building mobile/android')
+    if value:
+        return value[0]
+
+set_config('ANDROID_NDK', ndk)
+add_old_configure_assignment('android_ndk', ndk)
+
+@depends(target, host, ndk, '--with-android-toolchain',
+         '--with-android-gnu-compiler-version')
+@checking('for the Android toolchain directory', lambda x: x or 'not found')
+@imports(_from='mozbuild.shellutil', _import='quote')
+def android_toolchain(target, host, ndk, toolchain, gnu_compiler_version):
+    if not ndk:
+        return
+    if toolchain:
+        return toolchain[0]
+    else:
+        if target.cpu == 'arm' and target.endianness == 'little':
+            target_base = 'arm-linux-androideabi'
+        elif target.cpu == 'x86':
+            target_base = 'x86'
+        elif target.cpu == 'mips' and target.endianness == 'little':
+            target_base = 'mipsel-linux-android'
+        else:
+            die('Target cpu is not supported.')
+
+        toolchain_format = '%s/toolchains/%s-%s/prebuilt/%s-%s'
+
+        for version in gnu_compiler_version or ['4.9', '4.8', '4.7']:
+            toolchain = toolchain_format % (ndk, target_base, version,
+                                            host.kernel.lower(), host.cpu)
+            log.debug('Trying %s' % quote(toolchain))
+            if not os.path.isdir(toolchain) and host.cpu == 'x86_64':
+                toolchain = toolchain_format % (ndk, target_base, version,
+                                                host.kernel.lower(), 'x86')
+                log.debug('Trying %s' % quote(toolchain))
+            if os.path.isdir(toolchain):
+                return toolchain
+        else:
+            if gnu_compiler_version:
+                die('Your --with-android-gnu-compiler-version may be wrong')
+            die('You have to specify --with-android-toolchain='
+                '/path/to/ndk/toolchain.')
+
+set_config('ANDROID_TOOLCHAIN', android_toolchain)
+
+@depends(target, android_toolchain)
+def android_toolchain_prefix(target, toolchain):
+    if toolchain:
+        if target.cpu == 'x86':
+            # Ideally, the --target should just have the right x86 variant
+            # in the first place.
+            return '%s/bin/i686-linux-android-' % toolchain
+        return '%s/bin/%s-' % (toolchain, target.toolchain)
+
+imply_option('--with-toolchain-prefix', android_toolchain_prefix,
+             reason='--with-android-ndk')

--- a/build/moz.configure/old.configure
+++ b/build/moz.configure/old.configure
@@ -296,22 +296,19 @@ def old_configure_options(*options):
     '--enable-webspeechtestbackend',
     '--enable-xul',
     '--enable-zipwriter',
     '--no-create',
     '--prefix',
     '--with-adjust-sdk-keyfile',
     '--with-android-cxx-stl',
     '--with-android-distribution-directory',
-    '--with-android-gnu-compiler-version',
     '--with-android-max-sdk',
     '--with-android-min-sdk',
-    '--with-android-ndk',
     '--with-android-sdk',
-    '--with-android-toolchain',
     '--with-android-version',
     '--with-app-basename',
     '--with-app-name',
     '--with-arch',
     '--with-bing-api-keyfile',
     '--with-branding',
     '--with-crashreporter-enable-percent',
     '--with-cross-lib',

--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -54,16 +54,27 @@ def have_yasm(value):
     if value:
         return True
 
 set_config('HAVE_YASM', have_yasm)
 # Until the YASM variable is not necessary in old-configure.
 add_old_configure_assignment('YASM', have_yasm)
 
 
+# Android NDK
+# ==============================================================
+
+@depends('--disable-compile-environment', build_project, '--help')
+def android_ndk_include(compile_env, build_project, _):
+    if compile_env and build_project in ('mobile/android', 'js'):
+        return 'android-ndk.configure'
+
+include(android_ndk_include)
+
+
 # Compiler wrappers
 # ==============================================================
 js_option('--with-compiler-wrapper', env='COMPILER_WRAPPER', nargs=1,
           help='Enable compiling with wrappers such as distcc and ccache')
 
 js_option('--with-ccache', env='CCACHE', nargs='?',
           help='Enable compiling with ccache')
 
@@ -112,11 +123,11 @@ js_option('--with-toolchain-prefix', env
 def toolchain_prefix(value, target, host, cross_compiling):
     if value:
         return value[0]
     # Special case x86-64 <-> x86 cross compiling until we have the right tests
     # in moz.configure land.
     if cross_compiling and not all(i.cpu in ('x86_64', 'x86')
                                    for i in (target, host)):
         return '%s-' % target.toolchain
-    return ''
 
+set_config('TOOLCHAIN_PREFIX', toolchain_prefix)
 add_old_configure_assignment('TOOLCHAIN_PREFIX', toolchain_prefix)

--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -2728,18 +2728,16 @@ dnl ====================================
 MOZ_CHECK_ALLOCATOR
 
 AC_CHECK_FUNCS(setlocale localeconv)
 
 AC_SUBST(MOZILLA_VERSION)
 
 AC_SUBST(ac_configure_args)
 
-AC_SUBST(TOOLCHAIN_PREFIX)
-
 if test -n "$JS_STANDALONE"; then
 MOZ_APP_NAME="mozjs"
 MOZ_APP_VERSION="$MOZILLA_SYMBOLVERSION"
 JS_LIBRARY_NAME="mozjs-$MOZILLA_SYMBOLVERSION"
 else
 JS_LIBRARY_NAME="mozjs"
 fi
 JS_CONFIG_LIBS="$NSPR_LIBS $LIBS"

--- a/mobile/android/config/mozconfigs/android-api-15-frontend/nightly
+++ b/mobile/android/config/mozconfigs/android-api-15-frontend/nightly
@@ -5,16 +5,17 @@ MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_PACKAGE=0
 MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_SDK=0
 MOZ_AUTOMATION_UPDATE_PACKAGING=0
 MOZ_AUTOMATION_UPLOAD=0
 MOZ_AUTOMATION_UPLOAD_SYMBOLS=0
 
 NO_CACHE=1
+NO_NDK=1
 
 . "$topsrcdir/mobile/android/config/mozconfigs/common"
 
 ac_add_options --with-gradle="$topsrcdir/gradle/bin/gradle"
 export GRADLE_MAVEN_REPOSITORY="file://$topsrcdir/jcentral"
 
 ac_add_options --disable-compile-environment
 ac_add_options --disable-tests

--- a/mobile/android/config/mozconfigs/common
+++ b/mobile/android/config/mozconfigs/common
@@ -32,20 +32,23 @@ MOZ_SZIP_FLAGS="-D auto -f auto"
 
 ac_add_options --enable-elf-hack
 
 ANDROID_NDK_VERSION="r10e"
 ANDROID_NDK_VERSION_32BIT="r8c"
 
 # Build Fennec
 ac_add_options --enable-application=mobile/android
-ac_add_options --with-android-ndk="$topsrcdir/android-ndk"
 ac_add_options --with-android-sdk="$topsrcdir/android-sdk-linux"
 
-ac_add_options --with-android-gnu-compiler-version=4.9
+if [ -z "$NO_NDK" ]; then
+    ac_add_options --with-android-ndk="$topsrcdir/android-ndk"
+    ac_add_options --with-android-gnu-compiler-version=4.9
+fi
+
 ac_add_options --with-android-version=9
 ac_add_options --with-system-zlib
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 
 # Treat warnings as errors (modulo ALLOW_COMPILER_WARNINGS).
 ac_add_options --enable-warnings-as-errors
 
 ac_add_options --with-mozilla-api-keyfile=/builds/mozilla-fennec-geoloc-api.key

--- a/old-configure.in
+++ b/old-configure.in
@@ -98,17 +98,16 @@ MOZ_DEFAULT_COMPILER
 
 if test -n "$gonkdir" ; then
     dnl export for js/src/configure. We can't pass the option down normally,
     dnl because it's a `--enable-project=b2g`-only option.
     export gonkdir
     kernel_name=`uname -s | tr "[[:upper:]]" "[[:lower:]]"`
     android_source="$gonkdir"
     ANDROID_SOURCE="$android_source"
-    ANDROID_NDK="${ANDROID_SOURCE}/ndk"
     dnl Default to ICS
     ANDROID_VERSION=15
     if test -n "${PLATFORM_SDK_VERSION}"; then
         ANDROID_VERSION="${PLATFORM_SDK_VERSION}"
     fi
 
     if ! test -e "$gonkdir/ndk/sources/cxx-stl/stlport/src/iostream.cpp"; then
         AC_MSG_ERROR([Couldn't find path to stlport sources in the gonk tree])
@@ -6991,17 +6990,16 @@ AC_SUBST(WARNINGS_AS_ERRORS)
 AC_SUBST_SET(MOZ_EXTENSIONS)
 AC_SUBST(LIBICONV)
 AC_SUBST(MOZ_PLACES)
 AC_SUBST(MOZ_SOCIAL)
 AC_SUBST(MOZ_TOOLKIT_SEARCH)
 AC_SUBST(MOZ_FEEDS)
 AC_SUBST(NS_PRINTING)
 AC_SUBST(MOZ_HELP_VIEWER)
-AC_SUBST(TOOLCHAIN_PREFIX)
 
 AC_SUBST(JAVA)
 AC_SUBST(JAVAC)
 AC_SUBST(JAVAH)
 AC_SUBST(JAR)
 AC_SUBST(JARSIGNER)
 AC_SUBST(KEYTOOL)