diff --git a/browser/installer/package-manifest.in b/browser/installer/package-manifest.in
index 7ddefd0a4f06..ca31998c2057 100644
--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -622,6 +622,10 @@
 @RESPATH@/browser/chrome/webide.manifest
 @RESPATH@/browser/@PREF_DIR@/webide-prefs.js
 
+; [DevTools Shim Files]
+@RESPATH@/browser/chrome/devtools-shim@JAREXT@
+@RESPATH@/browser/chrome/devtools-shim.manifest
+
 ; DevTools
 @RESPATH@/browser/chrome/devtools@JAREXT@
 @RESPATH@/browser/chrome/devtools.manifest
diff --git a/devtools/client/framework/devtools.js b/devtools/client/framework/devtools.js
index 2c0c513de0ae..f880b241ec6c 100644
--- a/devtools/client/framework/devtools.js
+++ b/devtools/client/framework/devtools.js
@@ -8,6 +8,7 @@ const {Cu} = require("chrome");
 const Services = require("Services");
 
 // Load gDevToolsBrowser toolbox lazily as they need gDevTools to be fully initialized
+loader.lazyRequireGetter(this, "TargetFactory", "devtools/client/framework/target", true);
 loader.lazyRequireGetter(this, "Toolbox", "devtools/client/framework/toolbox", true);
 loader.lazyRequireGetter(this, "ToolboxHostManager", "devtools/client/framework/toolbox-host-manager", true);
 loader.lazyRequireGetter(this, "gDevToolsBrowser", "devtools/client/framework/devtools-browser", true);
@@ -468,6 +469,18 @@ DevTools.prototype = {
     return true;
   }),
 
+  /**
+   * Wrapper on TargetFactory.forTab, constructs a Target for the provided tab.
+   *
+   * @param  {XULTab} tab
+   *         The tab to use in creating a new target.
+   *
+   * @return {TabTarget} A target object
+   */
+  getTargetForTab: function (tab) {
+    return TargetFactory.forTab(tab);
+  },
+
   /**
    * Either the SDK Loader has been destroyed by the add-on contribution
    * workflow, or firefox is shutting down.
diff --git a/devtools/moz.build b/devtools/moz.build
index 3cfad8fae3a3..f988fd50dea9 100644
--- a/devtools/moz.build
+++ b/devtools/moz.build
@@ -15,6 +15,7 @@ if CONFIG['MOZ_DEVTOOLS'] == 'all':
 DIRS += [
     'server',
     'shared',
+    'shim',
 ]
 
 # /browser uses DIST_SUBDIR.  We opt-in to this treatment when building
diff --git a/devtools/shim/DevToolsShim.jsm b/devtools/shim/DevToolsShim.jsm
new file mode 100644
index 000000000000..581554d478c8
--- /dev/null
+++ b/devtools/shim/DevToolsShim.jsm
@@ -0,0 +1,170 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+this.EXPORTED_SYMBOLS = [
+  "DevToolsShim",
+];
+
+function removeItem(array, callback) {
+  let index = array.findIndex(callback);
+  if (index >= 0) {
+    array.splice(index, 1);
+  }
+}
+
+/**
+ * The DevToolsShim is a part of the DevTools go faster project, which moves the Firefox
+ * DevTools outside of mozilla-central to an add-on. It aims to bridge the gap for
+ * existing mozilla-central code that still needs to interact with DevTools (such as
+ * web-extensions).
+ *
+ * DevToolsShim is a singleton that provides a set of helpers to interact with DevTools,
+ * that work whether the DevTools addon is installed or not. It can be used to start
+ * listening to events, register tools, themes. As soon as a DevTools addon is installed
+ * the DevToolsShim will forward all the requests received until then to the real DevTools
+ * instance.
+ *
+ * DevToolsShim.isInstalled() can also be used to know if DevTools are currently
+ * installed.
+ */
+this.DevToolsShim = {
+  gDevTools: null,
+  listeners: [],
+  tools: [],
+  themes: [],
+
+  /**
+   * Check if DevTools are currently installed and available.
+   *
+   * @return {Boolean} true if DevTools are installed.
+   */
+  isInstalled: function () {
+    return !!this.gDevTools;
+  },
+
+  /**
+   * Register an instance of gDevTools. Should be called by DevTools during startup.
+   *
+   * @param {DevTools} a devtools instance (from client/framework/devtools)
+   */
+  register: function (gDevTools) {
+    this.gDevTools = gDevTools;
+    this._onDevToolsRegistered();
+  },
+
+  /**
+   * Unregister the current instance of gDevTools. Should be called by DevTools during
+   * shutdown.
+   */
+  unregister: function () {
+    this.gDevTools = null;
+  },
+
+  /**
+   * The following methods can be called before DevTools are installed:
+   * - on
+   * - off
+   * - registerTool
+   * - unregisterTool
+   * - registerTheme
+   * - unregisterTheme
+   *
+   * If DevTools are not installed when calling the method, DevToolsShim will call the
+   * appropriate method as soon as a gDevTools instance is registered.
+   */
+
+  /**
+   * This method is used by browser/components/extensions/ext-devtools.js for the events:
+   * - toolbox-created
+   * - toolbox-destroyed
+   */
+  on: function (event, listener) {
+    if (this.isInstalled()) {
+      this.gDevTools.on(event, listener);
+    } else {
+      this.listeners.push([event, listener]);
+    }
+  },
+
+  /**
+   * This method is currently only used by devtools code, but is kept here for consistency
+   * with on().
+   */
+  off: function (event, listener) {
+    if (this.isInstalled()) {
+      this.gDevTools.off(event, listener);
+    } else {
+      removeItem(this.listeners, ([e, l]) => e === event && l === listener);
+    }
+  },
+
+  /**
+   * This method is only used by the addon-sdk and should be removed when Firefox 56 is
+   * no longer supported.
+   */
+  registerTool: function (tool) {
+    if (this.isInstalled()) {
+      this.gDevTools.registerTool(tool);
+    } else {
+      this.tools.push(tool);
+    }
+  },
+
+  /**
+   * This method is only used by the addon-sdk and should be removed when Firefox 56 is
+   * no longer supported.
+   */
+  unregisterTool: function (tool) {
+    if (this.isInstalled()) {
+      this.gDevTools.unregisterTool(tool);
+    } else {
+      removeItem(this.tools, t => t === tool);
+    }
+  },
+
+  /**
+   * This method is only used by the addon-sdk and should be removed when Firefox 56 is
+   * no longer supported.
+   */
+  registerTheme: function (theme) {
+    if (this.isInstalled()) {
+      this.gDevTools.registerTheme(theme);
+    } else {
+      this.themes.push(theme);
+    }
+  },
+
+  /**
+   * This method is only used by the addon-sdk and should be removed when Firefox 56 is
+   * no longer supported.
+   */
+  unregisterTheme: function (theme) {
+    if (this.isInstalled()) {
+      this.gDevTools.unregisterTheme(theme);
+    } else {
+      removeItem(this.themes, t => t === theme);
+    }
+  },
+
+  _onDevToolsRegistered: function () {
+    // Register all pending event listeners on the real gDevTools object.
+    for (let [event, listener] of this.listeners) {
+      this.gDevTools.on(event, listener);
+    }
+
+    for (let tool of this.tools) {
+      this.gDevTools.registerTool(tool);
+    }
+
+    for (let theme of this.themes) {
+      this.gDevTools.registerTheme(theme);
+    }
+
+    this.listeners = [];
+    this.tools = [];
+    this.themes = [];
+  },
+};
diff --git a/devtools/shim/jar.mn b/devtools/shim/jar.mn
new file mode 100644
index 000000000000..5536034fecc7
--- /dev/null
+++ b/devtools/shim/jar.mn
@@ -0,0 +1,3 @@
+devtools-shim.jar:
+%   content devtools-shim %content/
+    content/DevToolsShim.jsm  (DevToolsShim.jsm)
diff --git a/devtools/shim/moz.build b/devtools/shim/moz.build
new file mode 100644
index 000000000000..552ad174f67d
--- /dev/null
+++ b/devtools/shim/moz.build
@@ -0,0 +1,3 @@
+JAR_MANIFESTS += ['jar.mn']
+
+XPCSHELL_TESTS_MANIFESTS += ['tests/unit/xpcshell.ini']
diff --git a/devtools/shim/tests/unit/.eslintrc.js b/devtools/shim/tests/unit/.eslintrc.js
new file mode 100644
index 000000000000..c25bec1e2c4c
--- /dev/null
+++ b/devtools/shim/tests/unit/.eslintrc.js
@@ -0,0 +1,21 @@
+// This file was copied from the .eslintrc.xpcshell.js
+// This new xpcshell test folder should stay in mozilla-central while devtools move to a
+// GitHub repository, hence the duplication.
+module.exports = {
+  "extends": [
+    "plugin:mozilla/xpcshell-test"
+  ],
+  "rules": {
+    // Allow non-camelcase so that run_test doesn't produce a warning.
+    "camelcase": "off",
+    // Allow using undefined variables so that tests can refer to functions
+    // and variables defined in head.js files, without having to maintain a
+    // list of globals in each .eslintrc file.
+    // Note that bug 1168340 will eventually help auto-registering globals
+    // from head.js files.
+    "no-undef": "off",
+    "block-scoped-var": "off",
+    // Tests can always import anything.
+    "mozilla/reject-some-requires": "off",
+  }
+};
diff --git a/devtools/shim/tests/unit/test_devtools_shim.js b/devtools/shim/tests/unit/test_devtools_shim.js
new file mode 100644
index 000000000000..8b4f48cb8fbe
--- /dev/null
+++ b/devtools/shim/tests/unit/test_devtools_shim.js
@@ -0,0 +1,192 @@
+/* -*- js-indent-level: 2; indent-tabs-mode: nil -*- */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { DevToolsShim } =
+    Components.utils.import("chrome://devtools-shim/content/DevToolsShim.jsm", {});
+
+// Test the DevToolsShim
+
+/**
+ * Create a mocked version of DevTools that records all calls made to methods expected
+ * to be called by DevToolsShim.
+ */
+function createMockDevTools() {
+  let methods = [
+    "on",
+    "off",
+    "registerTool",
+    "registerTheme",
+    "unregisterTool",
+    "unregisterTheme",
+  ];
+
+  let mock = {
+    callLog: {}
+  };
+
+  for (let method of methods) {
+    // Create a stub for method, that only pushes its arguments in the inner callLog
+    mock[method] = function (...args) {
+      mock.callLog[method].push(args);
+    };
+    mock.callLog[method] = [];
+  }
+
+  return mock;
+}
+
+/**
+ * Check if a given method was called an expected number of times, and finally check the
+ * arguments provided to the last call, if appropriate.
+ */
+function checkCalls(mock, method, length, lastArgs) {
+  ok(mock.callLog[method].length === length,
+      "Devtools.on was called the expected number of times");
+
+  // If we don't want to check the last call or if the method was never called, bail out.
+  if (!lastArgs || length === 0) {
+    return;
+  }
+
+  for (let i = 0; i < lastArgs.length; i++) {
+    let expectedArg = lastArgs[i];
+    ok(mock.callLog[method][length - 1][i] === expectedArg,
+        `Devtools.${method} was called with the expected argument (index ${i})`);
+  }
+}
+
+function test_register_unregister() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  DevToolsShim.register(createMockDevTools());
+  ok(DevToolsShim.isInstalled(), "DevTools are installed");
+
+  DevToolsShim.unregister();
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+}
+
+function test_on_is_forwarded_to_devtools() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  function cb1() {}
+  function cb2() {}
+  let mock = createMockDevTools();
+
+  DevToolsShim.on("test_event", cb1);
+  DevToolsShim.register(mock);
+  checkCalls(mock, "on", 1, ["test_event", cb1]);
+
+  DevToolsShim.on("other_event", cb2);
+  checkCalls(mock, "on", 2, ["other_event", cb2]);
+}
+
+function test_off_called_before_registering_devtools() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  function cb1() {}
+  let mock = createMockDevTools();
+
+  DevToolsShim.on("test_event", cb1);
+  DevToolsShim.off("test_event", cb1);
+
+  DevToolsShim.register(mock);
+  checkCalls(mock, "on", 0);
+}
+
+function test_off_called_before_with_bad_callback() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  function cb1() {}
+  function cb2() {}
+  let mock = createMockDevTools();
+
+  DevToolsShim.on("test_event", cb1);
+  DevToolsShim.off("test_event", cb2);
+
+  DevToolsShim.register(mock);
+  // on should still be called
+  checkCalls(mock, "on", 1, ["test_event", cb1]);
+  // Calls to off should not be held and forwarded.
+  checkCalls(mock, "off", 0);
+}
+
+function test_registering_tool() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  let tool1 = {};
+  let tool2 = {};
+  let tool3 = {};
+  let mock = createMockDevTools();
+
+  // Pre-register tool1
+  DevToolsShim.registerTool(tool1);
+
+  // Pre-register tool3, but unregister right after
+  DevToolsShim.registerTool(tool3);
+  DevToolsShim.unregisterTool(tool3);
+
+  DevToolsShim.register(mock);
+  checkCalls(mock, "registerTool", 1, [tool1]);
+
+  DevToolsShim.registerTool(tool2);
+  checkCalls(mock, "registerTool", 2, [tool2]);
+
+  DevToolsShim.unregister();
+
+  // Create a new mock and check the tools are not added once again.
+  mock = createMockDevTools();
+  DevToolsShim.register(mock);
+  checkCalls(mock, "registerTool", 0);
+}
+
+function test_registering_theme() {
+  ok(!DevToolsShim.isInstalled(), "DevTools are not installed");
+
+  let theme1 = {};
+  let theme2 = {};
+  let theme3 = {};
+  let mock = createMockDevTools();
+
+  // Pre-register theme1
+  DevToolsShim.registerTheme(theme1);
+
+  // Pre-register theme3, but unregister right after
+  DevToolsShim.registerTheme(theme3);
+  DevToolsShim.unregisterTheme(theme3);
+
+  DevToolsShim.register(mock);
+  checkCalls(mock, "registerTheme", 1, [theme1]);
+
+  DevToolsShim.registerTheme(theme2);
+  checkCalls(mock, "registerTheme", 2, [theme2]);
+
+  DevToolsShim.unregister();
+
+  // Create a new mock and check the themes are not added once again.
+  mock = createMockDevTools();
+  DevToolsShim.register(mock);
+  checkCalls(mock, "registerTheme", 0);
+}
+
+function run_test() {
+  test_register_unregister();
+  DevToolsShim.unregister();
+
+  test_on_is_forwarded_to_devtools();
+  DevToolsShim.unregister();
+
+  test_off_called_before_registering_devtools();
+  DevToolsShim.unregister();
+
+  test_off_called_before_with_bad_callback();
+  DevToolsShim.unregister();
+
+  test_registering_tool();
+  DevToolsShim.unregister();
+
+  test_registering_theme();
+  DevToolsShim.unregister();
+}
diff --git a/devtools/shim/tests/unit/xpcshell.ini b/devtools/shim/tests/unit/xpcshell.ini
new file mode 100644
index 000000000000..c329a440d988
--- /dev/null
+++ b/devtools/shim/tests/unit/xpcshell.ini
@@ -0,0 +1,6 @@
+[DEFAULT]
+tags = devtools
+firefox-appdir = browser
+skip-if = toolkit == 'android'
+
+[test_devtools_shim.js]