diff --git a/tools/wpt/browser.py b/tools/wpt/browser.py
index 692de7069e8831..46afdfed64b607 100644
--- a/tools/wpt/browser.py
+++ b/tools/wpt/browser.py
@@ -46,7 +46,7 @@ def find_webdriver(self, channel=None):
         return NotImplemented
 
     @abstractmethod
-    def version(self, binary=None):
+    def version(self, binary=None, webdriver_binary=None):
         """Retrieve the release version of the installed browser."""
         return NotImplemented
 
@@ -367,7 +367,7 @@ def install_geckodriver_nightly(self, dest):
 
         return path
 
-    def version(self, binary=None):
+    def version(self, binary=None, webdriver_binary=None):
         """Retrieve the release version of the installed browser."""
         version_string = call(binary, "--version").strip()
         m = re.match(r"Mozilla Firefox (.*)", version_string)
@@ -394,7 +394,7 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary=None):
+    def version(self, binary=None, webdriver_binary=None):
         return None
 
 
@@ -458,7 +458,7 @@ def install_webdriver(self, dest=None, channel=None):
         os.chmod(path, st.st_mode | stat.S_IEXEC)
         return path
 
-    def version(self, binary=None):
+    def version(self, binary=None, webdriver_binary=None):
         binary = binary or self.binary
         if uname[0] != "Windows":
             try:
@@ -497,7 +497,7 @@ def install_webdriver(self, dest=None, channel=None):
         chrome = Chrome()
         return chrome.install_webdriver(dest, channel)
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         return None
 
 class Opera(Browser):
@@ -562,7 +562,7 @@ def install_webdriver(self, dest=None, channel=None):
         os.chmod(path, st.st_mode | stat.S_IEXEC)
         return path
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         """Retrieve the release version of the installed browser."""
         binary = binary or self.binary
         try:
@@ -593,7 +593,7 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         return None
 
 
@@ -619,7 +619,7 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         return None
 
 
@@ -647,8 +647,24 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
-        return None
+    def version(self, binary=None, webdriver_binary=None):
+        if webdriver_binary is None:
+            logger.warn("Cannot find Safari version without safaridriver")
+            return None
+        # Use `safaridriver --version` to get the version. Example output:
+        # "Included with Safari 12.1 (14607.1.11)"
+        # "Included with Safari Technology Preview (Release 67, 13607.1.9.0.1)"
+        # The `--version` flag was added in STP 67, so allow the call to fail.
+        try:
+            version_string = call(webdriver_binary, "--version").strip()
+        except subprocess.CalledProcessError:
+            logger.warn("Failed to call %s --version", webdriver_binary)
+            return None
+        m = re.match(r"Included with Safari (.*)", version_string)
+        if not m:
+            logger.warn("Failed to extract version from: s%", version_string)
+            return None
+        return m.group(1)
 
 
 class SafariWebDriver(Safari):
@@ -707,7 +723,7 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         """Retrieve the release version of the installed browser."""
         output = call(binary, "--version")
         m = re.search(r"Servo ([0-9\.]+-[a-f0-9]+)?(-dirty)?$", output.strip())
@@ -737,7 +753,7 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         return None
 
 
@@ -759,5 +775,5 @@ def find_webdriver(self, channel=None):
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
 
-    def version(self, binary):
+    def version(self, binary=None, webdriver_binary=None):
         return None
diff --git a/tools/wpt/run.py b/tools/wpt/run.py
index b977d8a0cd68cc..093bc013c1b3b1 100644
--- a/tools/wpt/run.py
+++ b/tools/wpt/run.py
@@ -509,7 +509,8 @@ def setup_wptrunner(venv, prompt=True, install_browser=False, **kwargs):
 
     venv.install_requirements(os.path.join(wptrunner_path, "requirements.txt"))
 
-    kwargs['browser_version'] = setup_cls.browser.version(kwargs.get("binary"))
+    kwargs['browser_version'] = setup_cls.browser.version(binary=kwargs.get("binary"),
+                                                          webdriver_binary=kwargs.get("webdriver_binary"))
     return kwargs
 
 
diff --git a/tools/wpt/tests/test_browser.py b/tools/wpt/tests/test_browser.py
new file mode 100644
index 00000000000000..4ce8606949c2e9
--- /dev/null
+++ b/tools/wpt/tests/test_browser.py
@@ -0,0 +1,32 @@
+import mock
+import subprocess
+
+from tools.wpt import browser
+
+@mock.patch('subprocess.check_output')
+def test_safari_version(mocked_check_output):
+    safari = browser.Safari()
+
+    # Safari
+    mocked_check_output.return_value = 'Included with Safari 12.1 (14607.1.11)'
+    assert safari.version(webdriver_binary="safaridriver") == '12.1 (14607.1.11)'
+
+    # Safari Technology Preview
+    mocked_check_output.return_value = 'Included with Safari Technology Preview (Release 67, 13607.1.9.0.1)'
+    assert safari.version(webdriver_binary="safaridriver") == 'Technology Preview (Release 67, 13607.1.9.0.1)'
+
+@mock.patch('subprocess.check_output')
+def test_safari_version_errors(mocked_check_output):
+    safari = browser.Safari()
+
+    # No webdriver_binary
+    assert safari.version() is None
+
+    # `safaridriver --version` return gibberish
+    mocked_check_output.return_value = 'gibberish'
+    assert safari.version(webdriver_binary="safaridriver") is None
+
+    # `safaridriver --version` fails (as it does for Safari <=12.0)
+    mocked_check_output.return_value = 'dummy'
+    mocked_check_output.side_effect = subprocess.CalledProcessError(1, 'cmd')
+    assert safari.version(webdriver_binary="safaridriver") is None
diff --git a/tools/wpt/tests/test_run.py b/tools/wpt/tests/test_run.py
index ac860e3f8c0b14..94b1202736f5de 100644
--- a/tools/wpt/tests/test_run.py
+++ b/tools/wpt/tests/test_run.py
@@ -57,9 +57,9 @@ def test_setup_wptrunner(venv, product):
     parser = run.create_parser()
     kwargs = vars(parser.parse_args(["--channel=nightly", product]))
     kwargs["prompt"] = False
-    kwargs["webdriver_binary"] = "fake"
     # Hack to get a real existing path
     kwargs["binary"] = sys.argv[0]
+    kwargs["webdriver_binary"] = sys.argv[0]
     if kwargs["product"] == "sauce":
         kwargs["product"] = "sauce:firefox:63"
     run.setup_wptrunner(venv, **kwargs)