diff --git a/components/config/opts.rs b/components/config/opts.rs
index 4abcf1f8421..df2bb2e041e 100644
--- a/components/config/opts.rs
+++ b/components/config/opts.rs
@@ -573,6 +573,8 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
     let (app_name, args) = args.split_first().unwrap();
 
     let mut opts = Options::new();
+    opts.optflag("c", "cpu", "CPU painting");
+    opts.optflag("g", "gpu", "GPU painting");
     opts.optopt("o", "output", "Output file", "output.png");
     opts.optopt("s", "size", "Size of tiles", "512");
     opts.optopt("", "device-pixel-ratio", "Device pixels per px", "");
@@ -618,6 +620,7 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
     opts.optmulti("", "pref",
                   "A preference to set to enable", "dom.mozbrowser.enabled");
     opts.optflag("b", "no-native-titlebar", "Do not use native titlebar");
+    opts.optflag("w", "webrender", "Use webrender backend");
     opts.optopt("G", "graphics", "Select graphics backend (gl or es2)", "gl");
     opts.optopt("", "config-dir",
                     "config directory following xdg spec on linux platform", "");
diff --git a/tests/heartbeats/characterize.py b/tests/heartbeats/characterize.py
index 22f2028e388..948f5b9de43 100644
--- a/tests/heartbeats/characterize.py
+++ b/tests/heartbeats/characterize.py
@@ -210,6 +210,9 @@ def main():
     parser.add_argument("-d", "--debug",
                         action='store_true',
                         help="Use debug build instead of release build")
+    parser.add_argument("-w", "--webrender",
+                        action='store_true',
+                        help="Use webrender backend")
     parser.add_argument("-l", "--max_layout_threads",
                         help="Specify the maximum number of threads for layout, for example \"-l 5\"")
     parser.add_argument("-o", "--output",
@@ -230,6 +233,8 @@ def main():
         benchmark = args.benchmark
     if args.debug:
         build_target = "debug"
+    if args.webrender:
+        renderer = "-w"
     if args.max_layout_threads:
         max_layout_threads = int(args.max_layout_threads)
     if args.output:
diff --git a/tests/heartbeats/characterize_android.py b/tests/heartbeats/characterize_android.py
index 0b9b0807fe5..aae26ac2cbb 100644
--- a/tests/heartbeats/characterize_android.py
+++ b/tests/heartbeats/characterize_android.py
@@ -85,6 +85,9 @@ def main():
     parser.add_argument("-b", "--benchmark",
                         default=benchmark,
                         help="Gets the benchmark, for example \"-b http://www.example.com\"")
+    parser.add_argument("-w", "--webrender",
+                        action='store_true',
+                        help="Use webrender backend")
     parser.add_argument("-l", "--layout_threads",
                         help="Specify the number of threads for layout, for example \"-l 5\"")
     parser.add_argument("-o", "--output",
@@ -96,6 +99,8 @@ def main():
     args = parser.parse_args()
     if args.benchmark:
         benchmark = args.benchmark
+    if args.webrender:
+        renderer = "-w"
     if args.layout_threads:
         layout_threads = int(args.layout_threads)
     if args.output:
diff --git a/tests/wpt/harness/wptrunner/browsers/servo.py b/tests/wpt/harness/wptrunner/browsers/servo.py
index 64f572d331a..2eeb5aaa158 100644
--- a/tests/wpt/harness/wptrunner/browsers/servo.py
+++ b/tests/wpt/harness/wptrunner/browsers/servo.py
@@ -10,20 +10,17 @@ from ..executors.executorservo import ServoTestharnessExecutor, ServoRefTestExec
 
 here = os.path.join(os.path.split(__file__)[0])
 
-__wptrunner__ = {
-    "product": "servo",
-    "check_args": "check_args",
-    "browser": "ServoBrowser",
-    "executor": {
-        "testharness": "ServoTestharnessExecutor",
-        "reftest": "ServoRefTestExecutor",
-        "wdspec": "ServoWdspecExecutor",
-    },
-    "browser_kwargs": "browser_kwargs",
-    "executor_kwargs": "executor_kwargs",
-    "env_options": "env_options",
-    "update_properties": "update_properties",
-}
+__wptrunner__ = {"product": "servo",
+                 "check_args": "check_args",
+                 "browser": "ServoBrowser",
+                 "executor": {"testharness": "ServoTestharnessExecutor",
+                              "reftest": "ServoRefTestExecutor",
+                              "wdspec": "ServoWdspecExecutor"},
+                 "browser_kwargs": "browser_kwargs",
+                 "executor_kwargs": "executor_kwargs",
+                 "env_options": "env_options",
+                 "run_info_extras": "run_info_extras",
+                 "update_properties": "update_properties"}
 
 
 def check_args(**kwargs):
@@ -31,12 +28,11 @@ def check_args(**kwargs):
 
 
 def browser_kwargs(**kwargs):
-    return {
-        "binary": kwargs["binary"],
-        "debug_info": kwargs["debug_info"],
-        "binary_args": kwargs["binary_args"],
-        "user_stylesheets": kwargs.get("user_stylesheets"),
-    }
+    return {"binary": kwargs["binary"],
+            "debug_info": kwargs["debug_info"],
+            "binary_args": kwargs["binary_args"],
+            "user_stylesheets": kwargs.get("user_stylesheets"),
+            "render_backend": kwargs.get("servo_backend")}
 
 
 def executor_kwargs(test_type, server_config, cache_manager, run_info_data,
@@ -55,23 +51,31 @@ def env_options():
             "supports_debugger": True}
 
 
+def run_info_extras(**kwargs):
+    return {"backend": kwargs["servo_backend"]}
+
+
 def update_properties():
-    return ["debug", "os", "version", "processor", "bits"], None
+    return ["debug", "os", "version", "processor", "bits", "backend"], None
+
+
+def render_arg(render_backend):
+    return {"cpu": "--cpu", "webrender": "-w"}[render_backend]
 
 
 class ServoBrowser(NullBrowser):
     def __init__(self, logger, binary, debug_info=None, binary_args=None,
-                 user_stylesheets=None):
+                 user_stylesheets=None, render_backend="webrender"):
         NullBrowser.__init__(self, logger)
         self.binary = binary
         self.debug_info = debug_info
         self.binary_args = binary_args or []
         self.user_stylesheets = user_stylesheets or []
+        self.render_backend = render_backend
 
     def executor_browser(self):
-        return ExecutorBrowser, {
-            "binary": self.binary,
-            "debug_info": self.debug_info,
-            "binary_args": self.binary_args,
-            "user_stylesheets": self.user_stylesheets,
-        }
+        return ExecutorBrowser, {"binary": self.binary,
+                                 "debug_info": self.debug_info,
+                                 "binary_args": self.binary_args,
+                                 "user_stylesheets": self.user_stylesheets,
+                                 "render_backend": self.render_backend}
diff --git a/tests/wpt/harness/wptrunner/browsers/servodriver.py b/tests/wpt/harness/wptrunner/browsers/servodriver.py
index 4f4a7867168..ab4dc7956b9 100644
--- a/tests/wpt/harness/wptrunner/browsers/servodriver.py
+++ b/tests/wpt/harness/wptrunner/browsers/servodriver.py
@@ -9,25 +9,23 @@ import tempfile
 from mozprocess import ProcessHandler
 
 from .base import Browser, require_arg, get_free_port, browser_command, ExecutorBrowser
+from .servo import render_arg
 from ..executors import executor_kwargs as base_executor_kwargs
 from ..executors.executorservodriver import (ServoWebDriverTestharnessExecutor,
                                              ServoWebDriverRefTestExecutor)
 
 here = os.path.join(os.path.split(__file__)[0])
 
-__wptrunner__ = {
-    "product": "servodriver",
-    "check_args": "check_args",
-    "browser": "ServoWebDriverBrowser",
-    "executor": {
-        "testharness": "ServoWebDriverTestharnessExecutor",
-        "reftest": "ServoWebDriverRefTestExecutor",
-    },
-    "browser_kwargs": "browser_kwargs",
-    "executor_kwargs": "executor_kwargs",
-    "env_options": "env_options",
-    "update_properties": "update_properties",
-}
+__wptrunner__ = {"product": "servodriver",
+                 "check_args": "check_args",
+                 "browser": "ServoWebDriverBrowser",
+                 "executor": {"testharness": "ServoWebDriverTestharnessExecutor",
+                              "reftest": "ServoWebDriverRefTestExecutor"},
+                 "browser_kwargs": "browser_kwargs",
+                 "executor_kwargs": "executor_kwargs",
+                 "env_options": "env_options",
+                 "run_info_extras": "run_info_extras",
+                 "update_properties": "update_properties"}
 
 hosts_text = """127.0.0.1 web-platform.test
 127.0.0.1 www.web-platform.test
@@ -43,11 +41,10 @@ def check_args(**kwargs):
 
 
 def browser_kwargs(**kwargs):
-    return {
-        "binary": kwargs["binary"],
-        "debug_info": kwargs["debug_info"],
-        "user_stylesheets": kwargs.get("user_stylesheets"),
-    }
+    return {"binary": kwargs["binary"],
+            "debug_info": kwargs["debug_info"],
+            "user_stylesheets": kwargs.get("user_stylesheets"),
+            "render_backend": kwargs.get("servo_backend")}
 
 
 def executor_kwargs(test_type, server_config, cache_manager, run_info_data, **kwargs):
@@ -64,8 +61,12 @@ def env_options():
             "supports_debugger": True}
 
 
+def run_info_extras(**kwargs):
+    return {"backend": kwargs["servo_backend"]}
+
+
 def update_properties():
-    return ["debug", "os", "version", "processor", "bits"], None
+    return ["debug", "os", "version", "processor", "bits", "backend"], None
 
 
 def make_hosts_file():
@@ -79,7 +80,7 @@ class ServoWebDriverBrowser(Browser):
     used_ports = set()
 
     def __init__(self, logger, binary, debug_info=None, webdriver_host="127.0.0.1",
-                 user_stylesheets=None):
+                 user_stylesheets=None, render_backend="webrender"):
         Browser.__init__(self, logger)
         self.binary = binary
         self.webdriver_host = webdriver_host
@@ -89,6 +90,7 @@ class ServoWebDriverBrowser(Browser):
         self.hosts_path = make_hosts_file()
         self.command = None
         self.user_stylesheets = user_stylesheets if user_stylesheets else []
+        self.render_backend = render_backend
 
     def start(self):
         self.webdriver_port = get_free_port(4444, exclude=self.used_ports)
@@ -98,15 +100,11 @@ class ServoWebDriverBrowser(Browser):
         env["HOST_FILE"] = self.hosts_path
         env["RUST_BACKTRACE"] = "1"
 
-        debug_args, command = browser_command(
-            self.binary,
-            [
-                "--hard-fail",
-                "--webdriver", str(self.webdriver_port),
-                "about:blank",
-            ],
-            self.debug_info
-        )
+        debug_args, command = browser_command(self.binary,
+                                              [render_arg(self.render_backend), "--hard-fail",
+                                               "--webdriver", str(self.webdriver_port),
+                                               "about:blank"],
+                                              self.debug_info)
 
         for stylesheet in self.user_stylesheets:
             command += ["--user-stylesheet", stylesheet]
diff --git a/tests/wpt/harness/wptrunner/executors/executorservo.py b/tests/wpt/harness/wptrunner/executors/executorservo.py
index 99374f6f4a3..b627223a7df 100644
--- a/tests/wpt/harness/wptrunner/executors/executorservo.py
+++ b/tests/wpt/harness/wptrunner/executors/executorservo.py
@@ -30,10 +30,15 @@ from ..webdriver_server import ServoDriverServer
 from .executormarionette import WdspecRun
 
 pytestrunner = None
+render_arg = None
 webdriver = None
 
 extra_timeout = 5 # seconds
 
+def do_delayed_imports():
+    global render_arg
+    from ..browsers.servo import render_arg
+
 hosts_text = """127.0.0.1 web-platform.test
 127.0.0.1 www.web-platform.test
 127.0.0.1 www1.web-platform.test
@@ -75,10 +80,8 @@ class ServoTestharnessExecutor(ProcessTestExecutor):
         self.result_data = None
         self.result_flag = threading.Event()
 
-        args = [
-            "--hard-fail", "-u", "Servo/wptrunner",
-            "-Z", "replace-surrogates", "-z", self.test_url(test),
-        ]
+        args = [render_arg(self.browser.render_backend), "--hard-fail", "-u", "Servo/wptrunner",
+                "-Z", "replace-surrogates", "-z", self.test_url(test)]
         for stylesheet in self.browser.user_stylesheets:
             args += ["--user-stylesheet", stylesheet]
         for pref, value in test.environment.get('prefs', {}).iteritems():
@@ -210,12 +213,9 @@ class ServoRefTestExecutor(ProcessTestExecutor):
         with TempFilename(self.tempdir) as output_path:
             debug_args, command = browser_command(
                 self.binary,
-                [
-                    "--hard-fail", "--exit",
-                    "-u", "Servo/wptrunner",
-                    "-Z", "disable-text-aa,load-webfonts-synchronously,replace-surrogates",
-                    "--output=%s" % output_path, full_url
-                ] + self.browser.binary_args,
+                [render_arg(self.browser.render_backend), "--hard-fail", "--exit",
+                 "-u", "Servo/wptrunner", "-Z", "disable-text-aa,load-webfonts-synchronously,replace-surrogates",
+                 "--output=%s" % output_path, full_url] + self.browser.binary_args,
                 self.debug_info)
 
             for stylesheet in self.browser.user_stylesheets:
@@ -295,7 +295,7 @@ class ServoWdspecProtocol(Protocol):
 
     def setup(self, runner):
         try:
-            self.server = ServoDriverServer(self.logger, binary=self.browser.binary, binary_args=self.browser.binary_args)
+            self.server = ServoDriverServer(self.logger, binary=self.browser.binary, binary_args=self.browser.binary_args, render_backend=self.browser.render_backend)
             self.server.start(block=False)
             self.logger.info(
                 "WebDriver HTTP server listening at %s" % self.server.url)
diff --git a/tests/wpt/harness/wptrunner/webdriver_server.py b/tests/wpt/harness/wptrunner/webdriver_server.py
index 65c996d36d9..3b2b095a4a5 100644
--- a/tests/wpt/harness/wptrunner/webdriver_server.py
+++ b/tests/wpt/harness/wptrunner/webdriver_server.py
@@ -165,11 +165,12 @@ class GeckoDriverServer(WebDriverServer):
 
 
 class ServoDriverServer(WebDriverServer):
-    def __init__(self, logger, binary="servo", binary_args=None, host="127.0.0.1", port=None):
+    def __init__(self, logger, binary="servo", binary_args=None, host="127.0.0.1", port=None, render_backend=None):
         env = os.environ.copy()
         env["RUST_BACKTRACE"] = "1"
         WebDriverServer.__init__(self, logger, binary, host=host, port=port, env=env)
         self.binary_args = binary_args
+        self.render_backend = render_backend
 
     def make_command(self):
         command = [self.binary,
@@ -178,6 +179,10 @@ class ServoDriverServer(WebDriverServer):
                    "--headless"]
         if self.binary_args:
             command += self.binary_args
+        if self.render_backend == "cpu":
+            command += ["--cpu"]
+        elif self.render_backend == "webrender":
+            command += ["--webrender"]
         return command
 
 
diff --git a/tests/wpt/harness/wptrunner/wptcommandline.py b/tests/wpt/harness/wptrunner/wptcommandline.py
index 6b2c078730c..38e7b8f5363 100644
--- a/tests/wpt/harness/wptrunner/wptcommandline.py
+++ b/tests/wpt/harness/wptrunner/wptcommandline.py
@@ -178,6 +178,10 @@ scheme host and port.""")
     servo_group.add_argument("--user-stylesheet",
                              default=[], action="append", dest="user_stylesheets",
                              help="Inject a user CSS stylesheet into every test.")
+    servo_group.add_argument("--servo-backend",
+                             default="webrender", choices=["cpu", "webrender"],
+                             help="Rendering backend to use with Servo.")
+
 
     parser.add_argument("test_list", nargs="*",
                         help="List of URLs for tests to run, or paths including tests to run. "
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/canvas/to-data-url-test.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/canvas/to-data-url-test.html.ini
index c57a75b9b7f..11c670ec1ab 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/canvas/to-data-url-test.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/canvas/to-data-url-test.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/constants-and-properties.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/constants-and-properties.html.ini
index 8d71d201fe5..678d0b3b207 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/constants-and-properties.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/constants-and-properties.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-attribute-preserve-drawing-buffer.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-attribute-preserve-drawing-buffer.html.ini
index 665db3d3854..4ffd392fe67 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-attribute-preserve-drawing-buffer.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-attribute-preserve-drawing-buffer.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation-and-destruction.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation-and-destruction.html.ini
index 8ea5e0cb173..1b7cd37a3da 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation-and-destruction.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation-and-destruction.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation.html.ini
index 5c14b32b61a..8e4ce10380d 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-creation.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-hidden-alpha.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-hidden-alpha.html.ini
index 37267c86521..594c48aaffb 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-hidden-alpha.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-hidden-alpha.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-lost-restored.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-lost-restored.html.ini
index a1421962f10..adda8b8b6a1 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-lost-restored.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-lost-restored.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-upon-reload.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-upon-reload.html.ini
index dba75970ad4..477e59cb772 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-upon-reload.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-upon-reload.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-with-workers.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-with-workers.html.ini
index 5296158d3e4..f177cdceb1a 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-with-workers.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-release-with-workers.html.ini
@@ -3,3 +3,4 @@
   expected:
     if os == "linux": TIMEOUT
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-type-test.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-type-test.html.ini
index d6be69e656d..43e33a30281 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-type-test.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/context/context-type-test.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays-out-of-bounds.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays-out-of-bounds.html.ini
index ccfd211cbad..f5c3b343f16 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays-out-of-bounds.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays-out-of-bounds.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH
diff --git a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays.html.ini b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays.html.ini
index 21e7799d9a5..8593a9e88b8 100644
--- a/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays.html.ini
+++ b/tests/wpt/metadata/webgl/conformance-1.0.3/conformance/extensions/angle-instanced-arrays.html.ini
@@ -2,3 +2,4 @@
   type: testharness
   expected:
     if os == "mac": CRASH
+    if not debug and (os == "mac") and (version == "OS X 10.10.5") and (processor == "x86_64") and (bits == 64) and (backend == "cpu"): CRASH