diff --git a/build/types/polyfill b/build/types/polyfill
index 1dbbd7c59e..13eb749ead 100644
--- a/build/types/polyfill
+++ b/build/types/polyfill
@@ -1,6 +1,7 @@
 # Polyfills used to emulate missing browsers features.
 
 +../../node_modules/eme-encryption-scheme-polyfill/index.js
++../../lib/polyfill/aria.js
 +../../lib/polyfill/encryption_scheme.js
 +../../lib/polyfill/fullscreen.js
 +../../lib/polyfill/mathround.js
diff --git a/lib/polyfill/aria.js b/lib/polyfill/aria.js
new file mode 100644
index 0000000000..388c37a5f8
--- /dev/null
+++ b/lib/polyfill/aria.js
@@ -0,0 +1,72 @@
+/*! @license
+ * Shaka Player
+ * Copyright 2016 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+goog.provide('shaka.polyfill.Aria');
+
+goog.require('shaka.log');
+goog.require('shaka.polyfill');
+
+/**
+ * @summary A polyfill to add support for the ARIAMixin interface mixin, for
+ * browsers that do not implement it (e.g. Firefox).
+ * Note that IE also does not support ARIAMixin, but this polyfill does not work
+ * for that platform, as it relies on getters and setters.
+ * @see https://w3c.github.io/aria/#ARIAMixin
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/Element
+ */
+shaka.polyfill.Aria = class {
+  /** Install the polyfill if needed. */
+  static install() {
+    // eslint-disable-next-line no-restricted-syntax
+    if (Object.getOwnPropertyDescriptor(Element.prototype, 'ariaHidden')) {
+      shaka.log.info('Using native ARIAMixin interface.');
+      return;
+    }
+    shaka.log.info('ARIAMixin interface not detected. Installing polyfill.');
+
+    // Define a list of all of the ARIAMixin properties that we have externs
+    // for.
+    const attributes = [
+      'ariaHidden',
+      'ariaLabel',
+      'ariaPressed',
+      'ariaSelected',
+    ];
+
+    // Add each attribute, one by one.
+    for (const attribute of attributes) {
+      shaka.polyfill.Aria.addARIAMixinAttribute_(attribute);
+    }
+  }
+
+  /**
+   * Adds an attribute with the given name.
+   * @param {string} name The name of the attribute, in camelCase.
+   * @private
+   */
+  static addARIAMixinAttribute_(name) {
+    const snakeCaseName = name.toLowerCase().replace('aria', 'aria-');
+    /* eslint-disable no-restricted-syntax */
+    Object.defineProperty(Element.prototype, name, {
+      get() {
+        const element = /** @type {!Element} */ (this);
+        return element.getAttribute(snakeCaseName);
+      },
+      set(value) {
+        const element = /** @type {!Element} */ (this);
+        if (value == null || value == undefined) {
+          element.removeAttribute(snakeCaseName);
+        } else {
+          element.setAttribute(snakeCaseName, value);
+        }
+      },
+    });
+    /* eslint-enable no-restricted-syntax */
+  }
+};
+
+
+shaka.polyfill.register(shaka.polyfill.Aria.install);
diff --git a/shaka-player.uncompiled.js b/shaka-player.uncompiled.js
index 117197f845..458d6a6026 100644
--- a/shaka-player.uncompiled.js
+++ b/shaka-player.uncompiled.js
@@ -32,6 +32,7 @@ goog.require('shaka.offline.OfflineManifestParser');
 goog.require('shaka.offline.OfflineScheme');
 goog.require('shaka.offline.Storage');
 goog.require('shaka.offline.indexeddb.StorageMechanism');
+goog.require('shaka.polyfill.Aria');
 goog.require('shaka.polyfill.EncryptionScheme');
 goog.require('shaka.polyfill.Fullscreen');
 goog.require('shaka.polyfill.MathRound');