--- a/build/gyp.mozbuild
+++ b/build/gyp.mozbuild
@@ -19,17 +19,16 @@ gyp_vars = {
     'enable_android_opensl': 1,
     # use_system_lib* still seems to be in use in trunk/build
     'use_system_libjpeg': 0,
     'use_system_libvpx': 0,
     'build_libjpeg': 0,
     'build_libvpx': 0,
     'build_libyuv': 0,
     'libyuv_dir': '/media/libyuv',
-    'yuv_disable_avx2': 0 if CONFIG['HAVE_X86_AVX2'] else 1,
 
     # saves 4MB when webrtc_trace is off
     'enable_lazy_trace_alloc': 1,
 
      # turn off mandatory use of NEON and instead use NEON detection
     'arm_neon': 0,
 
     'moz_widget_toolkit_gonk': 0,

--- a/configure.in
+++ b/configure.in
@@ -1346,30 +1346,16 @@ if test "$GNU_CC"; then
     HAVE_TOOLCHAIN_SUPPORT_MSSE4_1=
     _SAVE_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS -msse4.1"
     AC_TRY_COMPILE([asm ("pmulld %xmm6,%xmm0");],,AC_MSG_RESULT([yes])
                      [HAVE_TOOLCHAIN_SUPPORT_MSSE4_1=1],
                      AC_MSG_RESULT([no]))
     CFLAGS=$_SAVE_CFLAGS
 
-    case "${CPU_ARCH}" in
-    x86 | x86_64)
-      AC_MSG_CHECKING(for x86 AVX2 asm support in compiler)
-      AC_TRY_COMPILE([],
-                     [asm volatile ("vpermq      \$0xd8,%ymm0,%ymm0 \n");],
-                     result="yes", result="no")
-      AC_MSG_RESULT("$result")
-      if test "$result" = "yes"; then
-          HAVE_X86_AVX2=1
-          AC_DEFINE(HAVE_X86_AVX2)
-          AC_SUBST(HAVE_X86_AVX2)
-      fi
-    esac
-
     # Turn on GNU-specific warnings:
     # -Wall - turn on a lot of warnings
     # -Wpointer-arith - good to have
     # -Wdeclaration-after-statement - MSVC doesn't like these
     # -Werror=return-type - catches missing returns, zero false positives
     # -Werror=int-to-pointer-cast - catches cast to pointer from integer of different size
     # -Wtype-limits - catches overflow bugs, few false positives
     # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives

--- a/media/libyuv/include/libyuv/row.h
+++ b/media/libyuv/include/libyuv/row.h
@@ -169,18 +169,18 @@ extern "C" {
 // Visual C 2012 required for AVX2.
 #if defined(_M_IX86) && defined(_MSC_VER) && _MSC_VER >= 1700
 #define VISUALC_HAS_AVX2 1
 #endif  // VisualStudio >= 2012
 
 // The following are available on all x86 platforms, but
 // require VS2012, clang 3.4 or gcc 4.7.
 // The code supports NaCL but requires a new compiler and validator.
-#if !defined(LIBYUV_DISABLE_AVX2) && !defined(LIBYUV_DISABLE_X86) &&    \
-    (defined(VISUALC_HAS_AVX2) || defined(CLANG_HAS_AVX2) || defined(GCC_HAS_AVX2))
+#if !defined(LIBYUV_DISABLE_X86) && (defined(VISUALC_HAS_AVX2) || \
+    defined(CLANG_HAS_AVX2) || defined(GCC_HAS_AVX2))
 // Effects:
 #define HAS_ARGBPOLYNOMIALROW_AVX2
 #define HAS_ARGBSHUFFLEROW_AVX2
 #define HAS_ARGBCOPYALPHAROW_AVX2
 #define HAS_ARGBCOPYYTOALPHAROW_AVX2
 #endif
 
 // The following are require VS2012.

--- a/media/libyuv/libyuv.gyp
+++ b/media/libyuv/libyuv.gyp
@@ -8,17 +8,16 @@
 
 {
   'includes': [
     'libyuv.gypi',
   ],
   'variables': {
     'use_system_libjpeg%': 0,
     'yuv_disable_asm%': 0,
-    'yuv_disable_avx2%': 0,
     'build_neon': 0,
     'conditions': [
        ['target_arch == "arm" and arm_version >= 7 and (arm_neon == 1 or arm_neon_optional == 1)', {
          'build_neon': 1,
        }],
     ],
   },
   'conditions': [
@@ -107,39 +106,32 @@
         [ 'yuv_disable_asm!=0', {
           'defines': [
             # Enable the following 3 macros to turn off assembly for specified CPU.
             'LIBYUV_DISABLE_X86',
             'LIBYUV_DISABLE_NEON',
             'LIBYUV_DISABLE_MIPS',
           ],
         }],
-        [ 'yuv_disable_avx2==1', {
-          'defines': [
-            'LIBYUV_DISABLE_AVX2',
-          ]
-        }],
         ['build_with_mozilla==1', {
           'include_dirs': [
             '$(DEPTH)/dist/include',
           ],
           'direct_dependent_settings': {
             'include_dirs': [
               '$(DEPTH)/dist/include',
             ],
           },
         }],
       ],
       'defines': [
         # Enable the following 3 macros to turn off assembly for specified CPU.
         # 'LIBYUV_DISABLE_X86',
         # 'LIBYUV_DISABLE_NEON',
         # 'LIBYUV_DISABLE_MIPS',
-        # This disables AVX2 (Haswell) support, overriding compiler checks
-        # 'LIBYUV_DISABLE_AVX2',
         # Enable the following macro to build libyuv as a shared library (dll).
         # 'LIBYUV_USING_SHARED_LIBRARY',
       ],
       'include_dirs': [
         'include',
         '.',
       ],
       'direct_dependent_settings': {