--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -761,16 +761,23 @@ c_compiler = compiler('C', target)
 cxx_compiler = compiler('C++', target, c_compiler=c_compiler)
 host_c_compiler = compiler('C', host, other_compiler=c_compiler)
 host_cxx_compiler = compiler('C++', host, c_compiler=host_c_compiler,
                              other_compiler=cxx_compiler,
                              other_c_compiler=c_compiler)
 
 include('compile-checks.configure')
 
+have_64_bit = try_compile(body='static_assert(sizeof(void *) == 8, "")',
+                          check_msg='for 64-bit OS')
+
+set_config('HAVE_64BIT_BUILD', have_64_bit)
+set_define('HAVE_64BIT_BUILD', have_64_bit)
+add_old_configure_assignment('HAVE_64BIT_BUILD', have_64_bit)
+
 @depends(c_compiler)
 def default_debug_flags(compiler_info):
     # Debug info is ON by default.
     if compiler_info.type == 'msvc':
         return '-Zi'
     return '-g'
 
 option(env='MOZ_DEBUG_FLAGS',

--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -444,58 +444,16 @@ DIRENT_INO=d_ino
 MOZ_USER_DIR=".mozilla"
 
 MOZ_FIX_LINK_PATHS="-Wl,-rpath-link,${DIST}/bin -Wl,-rpath-link,${prefix}/lib"
 
 dnl Configure platform-specific CPU architecture compiler options.
 dnl ==============================================================
 MOZ_ARCH_OPTS
 
-dnl =================================================================
-dnl Set up and test static assertion macros used to avoid AC_TRY_RUN,
-dnl which is bad when cross compiling.
-dnl =================================================================
-if test "$COMPILE_ENVIRONMENT"; then
-configure_static_assert_macros='
-#define CONFIGURE_STATIC_ASSERT(condition) CONFIGURE_STATIC_ASSERT_IMPL(condition, __LINE__)
-#define CONFIGURE_STATIC_ASSERT_IMPL(condition, line) CONFIGURE_STATIC_ASSERT_IMPL2(condition, line)
-#define CONFIGURE_STATIC_ASSERT_IMPL2(condition, line) typedef int static_assert_line_##line[(condition) ? 1 : -1]
-'
-
-dnl test that the macros actually work:
-AC_MSG_CHECKING(that static assertion macros used in autoconf tests work)
-AC_CACHE_VAL(ac_cv_static_assertion_macros_work,
- [AC_LANG_SAVE
-  AC_LANG_C
-  ac_cv_static_assertion_macros_work="yes"
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(1)],
-                 ,
-                 ac_cv_static_assertion_macros_work="no")
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(0)],
-                 ac_cv_static_assertion_macros_work="no",
-                 )
-  AC_LANG_CPLUSPLUS
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(1)],
-                 ,
-                 ac_cv_static_assertion_macros_work="no")
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(0)],
-                 ac_cv_static_assertion_macros_work="no",
-                 )
-  AC_LANG_RESTORE
- ])
-AC_MSG_RESULT("$ac_cv_static_assertion_macros_work")
-if test "$ac_cv_static_assertion_macros_work" = "no"; then
-    AC_MSG_ERROR([Compiler cannot compile macros used in autoconf tests.])
-fi
-fi # COMPILE_ENVIRONMENT
-
 dnl ========================================================
 dnl Android libstdc++, placed here so it can use MOZ_ARCH
 dnl computed above.
 dnl ========================================================
 
 MOZ_ANDROID_CPU_ARCH
 MOZ_ANDROID_STLPORT
 
@@ -584,35 +542,16 @@ if test "$GNU_CXX"; then
     _DEFINES_CXXFLAGS='-DMOZILLA_CLIENT -include $(topobjdir)/js/src/js-confdefs.h'
     _USE_CPP_INCLUDE_FLAG=1
 
 else
     _DEFINES_CXXFLAGS='-DMOZILLA_CLIENT -D_JS_CONFDEFS_H_ $(ACDEFINES)'
 fi
 
 dnl ========================================================
-dnl Checking for 64-bit OS
-dnl ========================================================
-if test "$COMPILE_ENVIRONMENT"; then
-AC_LANG_SAVE
-AC_LANG_C
-AC_MSG_CHECKING(for 64-bit OS)
-AC_TRY_COMPILE([$configure_static_assert_macros],
-               [CONFIGURE_STATIC_ASSERT(sizeof(void*) == 8)],
-               result="yes", result="no")
-AC_MSG_RESULT("$result")
-if test "$result" = "yes"; then
-    AC_DEFINE(HAVE_64BIT_BUILD)
-    HAVE_64BIT_BUILD=1
-fi
-AC_SUBST(HAVE_64BIT_BUILD)
-AC_LANG_RESTORE
-fi # COMPILE_ENVIRONMENT
-
-dnl ========================================================
 dnl System overrides of the defaults for host
 dnl ========================================================
 case "$host" in
 *mingw*)
     if test -n "$_WIN32_MSVC"; then
         HOST_AR=lib
         HOST_AR_FLAGS='-NOLOGO -OUT:$@'
         HOST_CFLAGS="$HOST_CFLAGS -TC -nologo"

--- a/old-configure.in
+++ b/old-configure.in
@@ -605,58 +605,16 @@ if test "$COMPILE_ENVIRONMENT"; then
     MOZ_ARCH_OPTS
 else
     if test "$OS_TARGET" = Android -a x"$MOZ_WIDGET_TOOLKIT" != x"gonk"; then
         dnl Default Android builds to ARMv7.
         MOZ_ARCH=armv7-a
     fi
 fi # COMPILE_ENVIRONMENT
 
-dnl =================================================================
-dnl Set up and test static assertion macros used to avoid AC_TRY_RUN,
-dnl which is bad when cross compiling.
-dnl =================================================================
-if test "$COMPILE_ENVIRONMENT"; then
-configure_static_assert_macros='
-#define CONFIGURE_STATIC_ASSERT(condition) CONFIGURE_STATIC_ASSERT_IMPL(condition, __LINE__)
-#define CONFIGURE_STATIC_ASSERT_IMPL(condition, line) CONFIGURE_STATIC_ASSERT_IMPL2(condition, line)
-#define CONFIGURE_STATIC_ASSERT_IMPL2(condition, line) typedef int static_assert_line_##line[(condition) ? 1 : -1]
-'
-
-dnl test that the macros actually work:
-AC_MSG_CHECKING(that static assertion macros used in autoconf tests work)
-AC_CACHE_VAL(ac_cv_static_assertion_macros_work,
- [AC_LANG_SAVE
-  AC_LANG_C
-  ac_cv_static_assertion_macros_work="yes"
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(1)],
-                 ,
-                 ac_cv_static_assertion_macros_work="no")
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(0)],
-                 ac_cv_static_assertion_macros_work="no",
-                 )
-  AC_LANG_CPLUSPLUS
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(1)],
-                 ,
-                 ac_cv_static_assertion_macros_work="no")
-  AC_TRY_COMPILE([$configure_static_assert_macros],
-                 [CONFIGURE_STATIC_ASSERT(0)],
-                 ac_cv_static_assertion_macros_work="no",
-                 )
-  AC_LANG_RESTORE
- ])
-AC_MSG_RESULT("$ac_cv_static_assertion_macros_work")
-if test "$ac_cv_static_assertion_macros_work" = "no"; then
-    AC_MSG_ERROR([Compiler cannot compile macros used in autoconf tests.])
-fi
-fi # COMPILE_ENVIRONMENT
-
 dnl ========================================================
 dnl Android libstdc++, placed here so it can use MOZ_ARCH
 dnl computed above.
 dnl ========================================================
 
 MOZ_ANDROID_CPU_ARCH
 if test "$COMPILE_ENVIRONMENT"; then
     MOZ_ANDROID_STLPORT
@@ -813,36 +771,16 @@ if test "$GNU_CXX"; then
     _DEFINES_CXXFLAGS='-DMOZILLA_CLIENT -include $(topobjdir)/mozilla-config.h'
     _USE_CPP_INCLUDE_FLAG=1
 
 else
     _DEFINES_CXXFLAGS='-DMOZILLA_CLIENT -D_MOZILLA_CONFIG_H_ $(ACDEFINES)'
 fi
 
 dnl ========================================================
-dnl Checking for 64-bit OS
-dnl ========================================================
-if test "$COMPILE_ENVIRONMENT"; then
-AC_LANG_SAVE
-AC_LANG_C
-AC_MSG_CHECKING(for 64-bit OS)
-AC_TRY_COMPILE([$configure_static_assert_macros],
-               [CONFIGURE_STATIC_ASSERT(sizeof(void*) == 8)],
-               result="yes", result="no")
-AC_MSG_RESULT("$result")
-if test "$result" = "yes"; then
-    AC_DEFINE(HAVE_64BIT_BUILD)
-    HAVE_64BIT_BUILD=1
-fi
-AC_SUBST(HAVE_64BIT_BUILD)
-AC_LANG_RESTORE
-fi # COMPILE_ENVIRONMENT
-
-
-dnl ========================================================
 dnl = Use Valgrind
 dnl ========================================================
 MOZ_ARG_ENABLE_BOOL(valgrind,
 [  --enable-valgrind       Enable Valgrind integration hooks (default=no)],
     MOZ_VALGRIND=1,
     MOZ_VALGRIND= )
 if test -n "$MOZ_VALGRIND"; then
     MOZ_CHECK_HEADER([valgrind/valgrind.h], [],

--- a/toolkit/mozapps/installer/packager.py
+++ b/toolkit/mozapps/installer/packager.py
@@ -77,17 +77,17 @@ class ToolLauncher(object):
             if p in env:
                 env[p] = extra_linker_path + ':' + env[p]
             else:
                 env[p] = extra_linker_path
         for e in extra_env:
             env[e] = extra_env[e]
 
         # For VC12+, make sure we can find the right bitness of pgort1x0.dll
-        if not buildconfig.substs['HAVE_64BIT_BUILD']:
+        if not buildconfig.substs.get('HAVE_64BIT_BUILD'):
             for e in ('VS140COMNTOOLS', 'VS120COMNTOOLS'):
                 if e not in env:
                     continue
 
                 vcdir = os.path.abspath(os.path.join(env[e], '../../VC/bin'))
                 if os.path.exists(vcdir):
                     env['PATH'] = '%s;%s' % (vcdir, env['PATH'])
                     break