--- a/dom/media/systemservices/moz.build
+++ b/dom/media/systemservices/moz.build
@@ -52,16 +52,21 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gonk
     else:
         LOCAL_INCLUDES += [
             '%' + '%s/system/media/wilhelm/include' % CONFIG['ANDROID_SOURCE'],
         ]
 
 if CONFIG['_MSC_VER']:
     DEFINES['__PRETTY_FUNCTION__'] = '__FUNCSIG__'
 
+    # This is intended as a temporary workaround to enable building with VS2015.
+    # media\webrtc\trunk\webrtc/base/criticalsection.h(59): warning C4312:
+    # 'reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
+    CXXFLAGS += ['-wd4312']
+
 EXPORTS.mozilla += ['ShmemPool.h',]
 
 EXPORTS.mozilla.media += ['MediaChild.h',
                           'MediaParent.h',
                           'MediaSystemResourceClient.h',
                           'MediaSystemResourceManager.h',
                           'MediaSystemResourceManagerChild.h',
                           'MediaSystemResourceManagerParent.h',

--- a/ipc/glue/moz.build
+++ b/ipc/glue/moz.build
@@ -131,16 +131,22 @@ SOURCES += [
     'BackgroundChildImpl.cpp',
     'BackgroundParentImpl.cpp',
     'FileDescriptorSetChild.cpp',
     'FileDescriptorSetParent.cpp',
     'GeckoChildProcessHost.cpp',
     'URIUtils.cpp',
 ]
 
+if CONFIG['_MSC_VER']:
+    # This is intended as a temporary hack to support building with VS2015.
+    # 'reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
+    SOURCES['BackgroundChildImpl.cpp'].flags += ['-wd4312']
+    SOURCES['BackgroundParentImpl.cpp'].flags += ['-wd4312']
+
 LOCAL_INCLUDES += [
     '/caps',
     '/dom/broadcastchannel',
     '/dom/indexedDB',
     '/dom/workers',
     '/media/webrtc/trunk',
     '/xpcom/build',
 ]

--- a/media/webrtc/moz.build
+++ b/media/webrtc/moz.build
@@ -88,16 +88,17 @@ if CONFIG['MOZ_WEBRTC_SIGNALING']:
         'signaling/src/sdp/sipcc/sdp_base64.c',
         'signaling/src/sdp/sipcc/sdp_config.c',
         'signaling/src/sdp/sipcc/sdp_main.c',
         'signaling/src/sdp/sipcc/sdp_services_unix.c',
         'signaling/src/sdp/sipcc/sdp_token.c',
         'signaling/src/sdp/sipcc/sdp_utils.c',
     ]
 
+    GYP_DIRS['signaling'].sandbox_vars['ALLOW_COMPILER_WARNINGS'] = True
     GYP_DIRS['signaling'].non_unified_sources += signaling_non_unified_sources
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'gonk':
     GYP_DIRS += ['trunk/testing']
     GYP_DIRS['trunk/testing'].input = 'trunk/testing/gtest.gyp'
     GYP_DIRS['trunk/testing'].variables = gyp_vars
     # We allow warnings for third-party code that can be updated from upstream.
     GYP_DIRS['trunk/testing'].sandbox_vars['ALLOW_COMPILER_WARNINGS'] = True
@@ -107,9 +108,10 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'gonk
         GYP_DIRS += ['signalingtest']
         GYP_DIRS['signalingtest'].input = 'signaling/signaling.gyp'
         GYP_DIRS['signalingtest'].variables = gyp_vars.copy()
         GYP_DIRS['signalingtest'].variables.update(
             build_for_test=1,
             moz_webrtc_mediacodec=0,
             build_for_standalone=0
         )
+        GYP_DIRS['signalingtest'].sandbox_vars['ALLOW_COMPILER_WARNINGS'] = True
         GYP_DIRS['signalingtest'].non_unified_sources += signaling_non_unified_sources

--- a/media/webrtc/signaling/test/moz.build
+++ b/media/webrtc/signaling/test/moz.build
@@ -19,8 +19,14 @@ if CONFIG['OS_TARGET'] != 'WINNT' and CO
 include('/ipc/chromium/chromium-config.mozbuild')
 include('common.build')
 
 USE_LIBS += [
     '/media/webrtc/signalingtest/signaling_ecc/ecc',
     'mtransport_s',
 ]
 
+if CONFIG['_MSC_VER']:
+    # This is intended as a temporary workaround to enable warning free building
+    # with VS2015.
+    # reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
+    CXXFLAGS += ['-wd4312']
+