diff --git a/third_party/blink/web_tests/external/WPT_BASE_MANIFEST_6.json b/third_party/blink/web_tests/external/WPT_BASE_MANIFEST_6.json
index 4887d52..40d9f61 100644
--- a/third_party/blink/web_tests/external/WPT_BASE_MANIFEST_6.json
+++ b/third_party/blink/web_tests/external/WPT_BASE_MANIFEST_6.json
@@ -48059,6 +48059,18 @@
      {}
     ]
    ],
+   "css/css-fonts/font-weight-xxx-large.html": [
+    [
+     "css/css-fonts/font-weight-xxx-large.html",
+     [
+      [
+       "/css/css-fonts/font-weight-xxx-large-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "css/css-fonts/matching/fixed-stretch-style-over-weight.html": [
     [
      "css/css-fonts/matching/fixed-stretch-style-over-weight.html",
@@ -134141,6 +134153,9 @@
    "css/css-fonts/font-weight-normal-001-ref.xht": [
     []
    ],
+   "css/css-fonts/font-weight-xxx-large-ref.html": [
+    []
+   ],
    "css/css-fonts/idlharness-expected.txt": [
     []
    ],
@@ -356707,6 +356722,14 @@
    "21e70068f1876a9fc4cae1ec6ccc73be826063ae",
    "manual"
   ],
+  "css/css-fonts/font-weight-xxx-large-ref.html": [
+   "0cc1184a83a8d87edbaf0648e664dc1d9e1f0932",
+   "support"
+  ],
+  "css/css-fonts/font-weight-xxx-large.html": [
+   "327106668fdf7bc130112f3fee4968c21a1daea4",
+   "reftest"
+  ],
   "css/css-fonts/format-specifiers-variations.html": [
    "8caf2f3d6000a28c548c84a6fbe2d4c8de2ee5b7",
    "testharness"
diff --git a/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large-ref.html b/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large-ref.html
new file mode 100644
index 0000000..0cc1184
--- /dev/null
+++ b/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large-ref.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html lang="en">
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<title>CSS Test:  font-size: xxx-large; size equivalence</title>
+<link rel="author" title="Joel Olsson" href="joel_1st@hotmail.com">
+<body>
+<p>Test passes if the line below is identical, with matching font size.</p>
+<font size=7>Foo</font>
diff --git a/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large.html b/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large.html
new file mode 100644
index 0000000..3271066
--- /dev/null
+++ b/third_party/blink/web_tests/external/wpt/css/css-fonts/font-weight-xxx-large.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<title>CSS Test:  font-size: xxx-large; size equivalence</title>
+<link rel="author" title="Joel Olsson" href="joel_1st@hotmail.com">
+<link rel="help" href="https://www.w3.org/TR/css-fonts-4/#font-size-prop">
+<link rel="help" href="https://www.w3.org/TR/css-fonts-4/#absolute-size-mapping">
+<link rel="match" href="font-weight-xxx-large-ref.html">
+<body>
+<p>Test passes if the line below is identical, with matching font size.</p>
+<span style="font-size: xxx-large">Foo</span>