diff --git a/browserShim.js b/browserShim.js
new file mode 100644
index 0000000..6028a9c
--- /dev/null
+++ b/browserShim.js
@@ -0,0 +1,5 @@
+'use strict';
+
+var systemGlobal = require('./');
+
+module.exports = systemGlobal.shim();
diff --git a/implementation.js b/implementation.js
new file mode 100644
index 0000000..511fc86
--- /dev/null
+++ b/implementation.js
@@ -0,0 +1,14 @@
+/* globals self, window, global */
+/* eslint no-negated-condition: 0, no-new-func: 0 */
+
+'use strict';
+
+if (typeof self !== 'undefined') {
+	module.exports = self;
+} else if (typeof window !== 'undefined') {
+	module.exports = window;
+} else if (typeof global !== 'undefined') {
+	module.exports = global;
+} else {
+	module.exports = Function('return this')();
+}
diff --git a/index.js b/index.js
new file mode 100644
index 0000000..7c73cef
--- /dev/null
+++ b/index.js
@@ -0,0 +1,19 @@
+'use strict';
+
+var defineProperties = require('define-properties');
+
+var implementation = require('./implementation');
+var getPolyfill = require('./polyfill');
+var shim = require('./shim');
+
+var polyfill = getPolyfill();
+
+var getGlobal = function () { return polyfill; };
+
+defineProperties(getGlobal, {
+	getPolyfill: getPolyfill,
+	implementation: implementation,
+	shim: shim
+});
+
+module.exports = getGlobal;
diff --git a/polyfill.js b/polyfill.js
new file mode 100644
index 0000000..725de1c
--- /dev/null
+++ b/polyfill.js
@@ -0,0 +1,10 @@
+'use strict';
+
+var implementation = require('./implementation');
+
+module.exports = function getPolyfill() {
+	if (typeof System !== 'object' || !System.global || System.global.Math !== Math || System.global.Array !== Array) {
+		return implementation;
+	}
+	return System.global;
+};
diff --git a/shim.js b/shim.js
new file mode 100644
index 0000000..af7c671
--- /dev/null
+++ b/shim.js
@@ -0,0 +1,26 @@
+'use strict';
+
+var define = require('define-properties');
+var getPolyfill = require('./polyfill');
+
+module.exports = function shimSystemAndGlobal() {
+	var polyfill = getPolyfill();
+	define(
+		polyfill,
+		{ System: {} },
+		{ System: function () { return typeof System !== 'object'; } }
+	);
+	if (System.global !== polyfill) {
+		if (define.supportsDescriptors) {
+			Object.defineProperty(System, 'global', {
+				configurable: true,
+				enumerable: false,
+				value: polyfill,
+				writable: false
+			});
+		} else {
+			System.global = polyfill;
+		}
+	}
+	return polyfill;
+};