diff --git a/testing/web-platform/tests/interfaces/xslt.idl b/testing/web-platform/tests/interfaces/xslt.idl
new file mode 100644
index 000000000000..e97d8b000441
--- /dev/null
+++ b/testing/web-platform/tests/interfaces/xslt.idl
@@ -0,0 +1,16 @@
+// Content was manually copied July 12 2019
+// Source: https://wiki.whatwg.org/wiki/DOM_XSLTProcessor
+// There is no standard for this API. Only the link above, and notes in
+// the HTML5 standard (https://html.spec.whatwg.org/multipage/scripting.html#scriptTagXSLT)
+
+[Exposed=Window, Constructor]
+interface XSLTProcessor {
+  void importStylesheet(Node style);
+  [CEReactions] DocumentFragment transformToFragment(Node source, Document output);
+  [CEReactions] Document transformToDocument(Node source);
+  void setParameter([TreatNullAs=EmptyString] DOMString namespaceURI, DOMString localName, any value);
+  any getParameter([TreatNullAs=EmptyString] DOMString namespaceURI, DOMString localName);
+  void removeParameter([TreatNullAs=EmptyString] DOMString namespaceURI, DOMString localName);
+  void clearParameters();
+  void reset();
+};
diff --git a/testing/web-platform/tests/xslt/META.yml b/testing/web-platform/tests/xslt/META.yml
new file mode 100644
index 000000000000..9c059d2e9117
--- /dev/null
+++ b/testing/web-platform/tests/xslt/META.yml
@@ -0,0 +1,4 @@
+# NOTE: There is no standard for this API, only:
+# https://wiki.whatwg.org/wiki/DOM_XSLTProcessor
+# and the notes in the HTML5 spec, linked.
+spec: https://html.spec.whatwg.org/multipage/scripting.html#scriptTagXSLT
diff --git a/testing/web-platform/tests/xslt/externalScript.js b/testing/web-platform/tests/xslt/externalScript.js
new file mode 100644
index 000000000000..7a2bf3622554
--- /dev/null
+++ b/testing/web-platform/tests/xslt/externalScript.js
@@ -0,0 +1 @@
+window.externalScript = true;
diff --git a/testing/web-platform/tests/xslt/idlharness.window.js b/testing/web-platform/tests/xslt/idlharness.window.js
new file mode 100644
index 000000000000..51b0cd3dbac7
--- /dev/null
+++ b/testing/web-platform/tests/xslt/idlharness.window.js
@@ -0,0 +1,15 @@
+// META: script=/resources/WebIDLParser.js
+// META: script=/resources/idlharness.js
+
+'use strict';
+
+idl_test(
+  ['xslt'],
+  ['html'],
+  async idlArray => {
+    idlArray.add_objects({
+      XSLTProcessor: ['processor']
+    });
+    self.processor = new XSLTProcessor();
+  }
+);
diff --git a/testing/web-platform/tests/xslt/transformToFragment.tentative.window.js b/testing/web-platform/tests/xslt/transformToFragment.tentative.window.js
new file mode 100644
index 000000000000..7bb6a5685544
--- /dev/null
+++ b/testing/web-platform/tests/xslt/transformToFragment.tentative.window.js
@@ -0,0 +1,39 @@
+const cases = {
+  internal: '<script>window.internalScript = true;</script>',
+  external: '<script src="externalScript.js"></script>',
+};
+
+const loaded = new Promise(resolve => {
+  window.addEventListener('load', resolve);
+});
+
+Object.entries(cases).forEach(([k, v]) => {
+  const xsltSrc = `<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+<xsl:output method="html" encoding="utf-8" version="5"/>
+<xsl:template match="/">
+  <section>
+    ${v}
+  </section>
+</xsl:template>
+</xsl:stylesheet>`;
+
+  const processor = new XSLTProcessor();
+  const parser = new DOMParser();
+  processor.importStylesheet(
+    parser.parseFromString(xsltSrc, 'application/xml')
+  );
+  document.body.appendChild(
+    processor.transformToFragment(
+      parser.parseFromString('<x/>', 'application/xml'),
+      document
+    )
+  );
+
+  promise_test(async () => {
+    await loaded;
+    assert_true(
+      window[`${k}Script`],
+      'script element from XSLTProcessor.transformToFragment() is evaluated'
+    );
+  }, `${k} script`);
+})