new file mode 100644
--- /dev/null
+++ b/build/moz.configure/toolchain.configure
@@ -0,0 +1,61 @@
+# -*- 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/.
+
+# yasm detection
+# ==============================================================
+yasm = check_prog('YASM', ['yasm'], allow_missing=True)
+
+@depends(yasm)
+@checking('yasm version')
+@advanced
+def yasm_version(yasm):
+    if yasm:
+        import subprocess
+        try:
+            version = Version(subprocess.check_output(
+                [yasm, '--version']
+            ).splitlines()[0].split()[1])
+            return version
+        except subprocess.CalledProcessError as e:
+            error('Failed to get yasm version: %s' % e.message)
+
+# Until we move all the yasm consumers out of old-configure.
+# bug 1257904
+add_old_configure_assignment('_YASM_MAJOR_VERSION',
+                             delayed_getattr(yasm_version, 'major'))
+add_old_configure_assignment('_YASM_MINOR_VERSION',
+                             delayed_getattr(yasm_version, 'minor'))
+
+@depends(yasm, target)
+def yasm_asflags(yasm, target):
+    if yasm:
+        asflags = {
+            ('OSX', 'x86'): '-f macho32',
+            ('OSX', 'x86_64'): '-f macho64',
+            ('WINNT', 'x86'): '-f win32',
+            ('WINNT', 'x86_64'): '-f x64',
+        }.get((target.os, target.cpu), None)
+        if asflags is None:
+            # We're assuming every x86 platform we support that's
+            # not Windows or Mac is ELF.
+            if target.cpu == 'x86':
+                asflags = '-f elf32'
+            elif target.cpu == 'x86_64':
+                asflags = '-f elf64'
+        if asflags:
+            asflags += ' -rnasm -pnasm'
+        return asflags
+
+set_config('YASM_ASFLAGS', yasm_asflags)
+
+@depends(yasm_asflags)
+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)

--- a/moz.configure
+++ b/moz.configure
@@ -49,16 +49,23 @@ option('--disable-compile-environment',
 @depends('--disable-compile-environment')
 def compile_environment(value):
     if value:
         return True
 
 set_config('COMPILE_ENVIRONMENT', compile_environment)
 add_old_configure_assignment('COMPILE_ENVIRONMENT', compile_environment)
 
+@depends('--disable-compile-environment', '--help')
+def toolchain_include(value, help):
+    if value:
+        return 'build/moz.configure/toolchain.configure'
+
+include(toolchain_include)
+
 
 @depends('--help')
 @advanced
 def build_backends_choices(help):
     from mozbuild.backend import backends
     return tuple(backends)
 
 
@@ -130,73 +137,16 @@ def perl_version_check(min_version):
     def require_full_perl_installation(has_full_perl_installation):
         if not has_full_perl_installation:
             error('Cannot find Config.pm or $Config{archlib}. '
                   'A full perl installation is required.')
 
 perl_version_check('5.006')
 
 
-# yasm detection
-# ==============================================================
-yasm = check_prog('YASM', ['yasm'], allow_missing=True)
-
-@depends(yasm)
-@checking('yasm version')
-@advanced
-def yasm_version(yasm):
-    if yasm:
-        import subprocess
-        try:
-            version = Version(subprocess.check_output(
-                [yasm, '--version']
-            ).splitlines()[0].split()[1])
-            return version
-        except subprocess.CalledProcessError as e:
-            error('Failed to get yasm version: %s' % e.message)
-
-# Until we move all the yasm consumers out of old-configure.
-# bug 1257904
-add_old_configure_assignment('_YASM_MAJOR_VERSION',
-                             delayed_getattr(yasm_version, 'major'))
-add_old_configure_assignment('_YASM_MINOR_VERSION',
-                             delayed_getattr(yasm_version, 'minor'))
-
-@depends(yasm, target)
-def yasm_asflags(yasm, target):
-    if yasm:
-        asflags = {
-            ('OSX', 'x86'): '-f macho32',
-            ('OSX', 'x86_64'): '-f macho64',
-            ('WINNT', 'x86'): '-f win32',
-            ('WINNT', 'x86_64'): '-f x64',
-        }.get((target.os, target.cpu), None)
-        if asflags is None:
-            # We're assuming every x86 platform we support that's
-            # not Windows or Mac is ELF.
-            if target.cpu == 'x86':
-                asflags = '-f elf32'
-            elif target.cpu == 'x86_64':
-                asflags = '-f elf64'
-        if asflags:
-            asflags += ' -rnasm -pnasm'
-        return asflags
-
-set_config('YASM_ASFLAGS', yasm_asflags)
-
-@depends(yasm_asflags)
-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)
-
-
 # Miscellaneous programs
 # ==============================================================
 check_prog('DOXYGEN', ('doxygen',), allow_missing=True)
 check_prog('TAR', ('gnutar', 'gtar', 'tar'))
 check_prog('UNZIP', ('unzip',))
 check_prog('XARGS', ('xargs',))
 check_prog('ZIP', ('zip',))
 

--- a/old-configure.in
+++ b/old-configure.in
@@ -4818,17 +4818,17 @@ MOZ_ARG_DISABLE_BOOL(libjpeg_turbo,
 
 if test "$MOZ_SYSTEM_JPEG" = 1 -a "$MOZ_LIBJPEG_TURBO" = 1; then
     AC_MSG_ERROR([cannot use --with-system-jpeg with --enable-libjpeg-turbo.])
 fi
 
 dnl Detect if we can use yasm to compile libjpeg-turbo's optimized assembly
 dnl files.
 
-if test -n "$MOZ_LIBJPEG_TURBO"; then
+if test -n "$MOZ_LIBJPEG_TURBO" -a -n "$COMPILE_ENVIRONMENT"; then
 
   dnl Do we support libjpeg-turbo on this platform?
   case "$OS_ARCH:$CPU_ARCH" in
   Darwin:x86)
     LIBJPEG_TURBO_ASFLAGS="-DPIC -DMACHO"
   ;;
   Darwin:x86_64)
     LIBJPEG_TURBO_ASFLAGS="-D__x86_64__ -DPIC -DMACHO"
@@ -4905,17 +4905,17 @@ case "$OS_ARCH:$CPU_ARCH" in
   ;;
   *:x86_64)
       MOZ_LIBAV_FFT=1
   ;;
 esac
 
 dnl Detect if we can use yasm to compile libav's assembly
 
-if test -n "$MOZ_LIBAV_FFT"; then
+if test -n "$MOZ_LIBAV_FFT" -a -n "$COMPILE_ENVIRONMENT"; then
   AC_DEFINE(MOZ_LIBAV_FFT)
   dnl Do we support libav-fft on this platform?
   case "$OS_ARCH:$CPU_ARCH" in
   Darwin:x86_64)
     LIBAV_FFT_ASFLAGS="-D__x86_64__ -DPIC -DMACHO"
   ;;
   WINNT:x86)
     LIBAV_FFT_ASFLAGS="-DPIC -DWIN32"