--- a/config/config.mk
+++ b/config/config.mk
@@ -430,17 +430,17 @@ OS_COMPILE_CMFLAGS += -fobjc-abi-version
 OS_COMPILE_CMMFLAGS += -fobjc-abi-version=2 -fobjc-legacy-dispatch
 endif
 endif
 
 COMPILE_CFLAGS	= $(VISIBILITY_FLAGS) $(DEFINES) $(INCLUDES) $(OS_INCLUDES) $(DSO_CFLAGS) $(DSO_PIC_CFLAGS) $(RTL_FLAGS) $(OS_CPPFLAGS) $(OS_COMPILE_CFLAGS) $(CFLAGS) $(MOZBUILD_CFLAGS)
 COMPILE_CXXFLAGS = $(if $(DISABLE_STL_WRAPPING),,$(STL_FLAGS)) $(VISIBILITY_FLAGS) $(DEFINES) $(INCLUDES) $(OS_INCLUDES) $(DSO_CFLAGS) $(DSO_PIC_CFLAGS) $(RTL_FLAGS) $(OS_CPPFLAGS) $(OS_COMPILE_CXXFLAGS) $(CXXFLAGS) $(MOZBUILD_CXXFLAGS)
 COMPILE_CMFLAGS = $(OS_COMPILE_CMFLAGS) $(MOZBUILD_CMFLAGS)
 COMPILE_CMMFLAGS = $(OS_COMPILE_CMMFLAGS) $(MOZBUILD_CMMFLAGS)
-ASFLAGS += $(MOZBUILD_ASFLAGS) $(EXTRA_ASSEMBLER_FLAGS)
+ASFLAGS += $(MOZBUILD_ASFLAGS)
 
 ifndef CROSS_COMPILE
 HOST_CFLAGS += $(RTL_FLAGS)
 endif
 
 #
 # Name of the binary code directories
 #

--- a/python/mozbuild/mozbuild/frontend/emitter.py
+++ b/python/mozbuild/mozbuild/frontend/emitter.py
@@ -549,17 +549,16 @@ class TreeMetadataEmitter(LoggingMixin):
         # Proxy some variables as-is until we have richer classes to represent
         # them. We should aim to keep this set small because it violates the
         # desired abstraction of the build definition away from makefiles.
         passthru = VariablePassthru(context)
         varlist = [
             'ANDROID_GENERATED_RESFILES',
             'ANDROID_RES_DIRS',
             'DISABLE_STL_WRAPPING',
-            'EXTRA_ASSEMBLER_FLAGS',
             'EXTRA_COMPONENTS',
             'EXTRA_DSO_LDOPTS',
             'EXTRA_PP_COMPONENTS',
             'FAIL_ON_WARNINGS',
             'USE_STATIC_LIBS',
             'NO_DIST_INSTALL',
             'PYTHON_UNIT_TESTS',
             'RCFILE',

--- a/python/mozbuild/mozbuild/frontend/gyp_reader.py
+++ b/python/mozbuild/mozbuild/frontend/gyp_reader.py
@@ -66,19 +66,17 @@ class GypContext(TemplateContext):
             allowed_variables=self.VARIABLES(), config=config)
 
     @classmethod
     @memoize
     def VARIABLES(cls):
         """Returns the allowed variables for a GypContext."""
         # Using a class method instead of a class variable to hide the content
         # from sphinx.
-        return dict(VARIABLES,
-        EXTRA_ASSEMBLER_FLAGS=(List, list, '', None),
-    )
+        return dict(VARIABLES)
 
 
 def encode(value):
     if isinstance(value, unicode):
         return value.encode('utf-8')
     return value
 
 
@@ -198,17 +196,17 @@ def read_from_gyp(config, path, output, 
                 if include.startswith('/'):
                     resolved = mozpath.abspath(mozpath.join(config.topsrcdir, include[1:]))
                 else:
                     resolved = mozpath.abspath(mozpath.join(mozpath.dirname(build_file), include))
                 if not os.path.exists(resolved):
                     continue
                 context['LOCAL_INCLUDES'] += [include]
 
-            context['EXTRA_ASSEMBLER_FLAGS'] = target_conf.get('asflags_mozilla', [])
+            context['ASFLAGS'] = target_conf.get('asflags_mozilla', [])
             flags = target_conf.get('cflags_mozilla', [])
             if flags:
                 suffix_map = {
                     '.c': 'CFLAGS',
                     '.cpp': 'CXXFLAGS',
                     '.cc': 'CXXFLAGS',
                     '.m': 'CMFLAGS',
                     '.mm': 'CMMFLAGS',