diff --git a/lint.whitelist b/lint.whitelist
index ac2d30427cfe37..f9688ed58b98c0 100644
--- a/lint.whitelist
+++ b/lint.whitelist
@@ -108,6 +108,7 @@ CONSOLE: resources/check-layout-th.js
 CONSOLE: resources/chromium/*
 CONSOLE: resources/idlharness.js
 CONSOLE: streams/resources/test-utils.js
+CONSOLE: weakrefs/resources/test-utils.js
 CONSOLE: service-workers/service-worker/resources/navigation-redirect-other-origin.html
 CONSOLE: service-workers/service-worker/navigation-redirect.https.html
 CONSOLE: service-workers/service-worker/resources/clients-get-other-origin.html
diff --git a/weakrefs/META.yml b/weakrefs/META.yml
new file mode 100644
index 00000000000000..f8ef8886f3ba74
--- /dev/null
+++ b/weakrefs/META.yml
@@ -0,0 +1 @@
+spec: https://tc39.es/proposal-weakrefs/
diff --git a/weakrefs/finalization-group-basic.html b/weakrefs/finalization-group-basic.html
new file mode 100644
index 00000000000000..831ebf87a080ea
--- /dev/null
+++ b/weakrefs/finalization-group-basic.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script type="module">
+import garbageCollect from './resources/test-utils.js';
+
+async_test(function() {
+  let called = false;
+
+  const callback = this.step_func(function(iter) {
+    const values = [...iter];
+    assert_equals(values[0], 'holdings',
+                  'holdings should be initialized correctly');
+    this.done();
+  });
+
+  const fg = new FinalizationGroup(callback);
+
+  (function() {
+    let x = {};
+    fg.register(x, 'holdings');
+    x = null;
+  })();
+
+  assert_false(called, 'finalizer should not be called in the same turn');
+
+  garbageCollect();
+
+  assert_false(called, 'finalizer should not be called in the same turn');
+
+}, `FinalizationGroup registers an object and calls finalizer`);
+</script>
diff --git a/weakrefs/finalization-group-cleanupSome-basic.html b/weakrefs/finalization-group-cleanupSome-basic.html
new file mode 100644
index 00000000000000..118d64ed486248
--- /dev/null
+++ b/weakrefs/finalization-group-cleanupSome-basic.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script type="module">
+import garbageCollect from './resources/test-utils.js';
+
+test(function() {
+  let called = false;
+  function callback(iter) {
+    called = true;
+    const values = [...iter];
+    assert_equals(values[0], 'holdings',
+                  'holdings should be initialized correctly');
+  };
+
+  const fg = new FinalizationGroup(callback);
+
+  (function() {
+    let x = {};
+    fg.register(x, 'holdings');
+    x = null;
+  })();
+
+  assert_false(called, 'finalizer should not be called yet');
+
+  garbageCollect();
+
+  fg.cleanupSome();
+  assert_true(called, 'finalizer should be called');
+
+}, `FinalizationGroup.cleanupSome calls finalizer in same turn`);
+</script>
diff --git a/weakrefs/finalization-group-error.html b/weakrefs/finalization-group-error.html
new file mode 100644
index 00000000000000..60fa1da2ca12df
--- /dev/null
+++ b/weakrefs/finalization-group-error.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script type="module">
+import garbageCollect from './resources/test-utils.js';
+
+setup({allow_uncaught_exception : true});
+
+async_test(function() {
+  window.onerror = this.step_func(function(msg, source, lineno, colno, e) {
+    assert_equals(e.message, 'weakrefs are awesome',
+                  'Correct exception is thrown');
+    this.done();
+  });
+
+  function callback(iter) {
+    [...iter];
+    throw new Error('weakrefs are awesome');
+  };
+
+  const fg = new FinalizationGroup(callback);
+
+  (function() {
+    let x = {};
+    fg.register(x, 'holdings');
+    x = null;
+  })();
+
+  garbageCollect();
+}, `finalizer callback exceptions are reported to error handler`);
+</script>
diff --git a/weakrefs/resources/test-utils.js b/weakrefs/resources/test-utils.js
new file mode 100644
index 00000000000000..a836346969d48b
--- /dev/null
+++ b/weakrefs/resources/test-utils.js
@@ -0,0 +1,16 @@
+export default function() {
+  if (self.gc) {
+    // Use --expose_gc for V8 (and Node.js)
+    // to pass this flag at chrome launch use: --js-flags="--expose-gc"
+    // Exposed in SpiderMonkey shell as well
+    self.gc();
+  } else if (self.GCController) {
+    // Present in some WebKit development environments
+    GCController.collect();
+  } else {
+    /* eslint-disable no-console */
+    console.warn('Tests are running without the ability to do manual garbage collection. They will still work, but ' +
+      'coverage will be suboptimal.');
+    /* eslint-enable no-console */
+  }
+};
