--- a/devtools/client/debugger/babel.config.js
+++ b/devtools/client/debugger/babel.config.js
@@ -11,16 +11,17 @@ module.exports = {
   overrides: [
     {
       test: [
         "./src",
         "./packages/*/index.js",
         "./packages/*/src",
         /[/\\]node_modules[/\\]devtools-/,
         /[/\\]node_modules[/\\]react-aria-components[/\\]/,
+        "../../shared",
       ],
       presets: [
         "@babel/preset-react",
         [
           "@babel/preset-env",
           {
             targets: {
               browsers: ["last 1 Chrome version", "last 1 Firefox version"],

--- a/devtools/client/debugger/jest-test.config.js
+++ b/devtools/client/debugger/jest-test.config.js
@@ -36,12 +36,14 @@ module.exports = {
   snapshotSerializers: [
     "jest-serializer-babel-ast",
     "enzyme-to-json/serializer",
   ],
   moduleNameMapper: {
     "\\.css$": "<rootDir>/src/test/__mocks__/styleMock.js",
     "\\.svg$": "<rootDir>/src/test/__mocks__/svgMock.js",
     "^Services": "<rootDir>/src/test/fixtures/Services",
+    "^chrome": "<rootDir>/src/test/fixtures/Chrome",
+    "^ChromeUtils": "<rootDir>/src/test/fixtures/ChromeUtils",
     // Map all require("devtools/...") to the real devtools root.
     "^devtools\\/(.*)": "<rootDir>/../../$1",
   },
 };

--- a/devtools/client/debugger/src/client/firefox/types.js
+++ b/devtools/client/debugger/src/client/firefox/types.js
@@ -426,9 +426,10 @@ export type Panel = {|
   emit: (eventName: string) => void,
   openLink: (url: URL) => void,
   openInspector: () => void,
   openElementInInspector: (grip: Object) => void,
   openConsoleAndEvaluate: (input: string) => void,
   highlightDomElement: (grip: Object) => void,
   unHighlightDomElement: (grip: Object) => void,
   getToolboxStore: () => any,
+  panelWin: Object,
 |};

--- a/devtools/client/debugger/src/components/App.js
+++ b/devtools/client/debugger/src/components/App.js
@@ -53,24 +53,27 @@ import PrimaryPanes from "./PrimaryPanes
 import Editor from "./Editor";
 import SecondaryPanes from "./SecondaryPanes";
 import WelcomeBox from "./WelcomeBox";
 import EditorTabs from "./Editor/Tabs";
 import EditorFooter from "./Editor/Footer";
 import QuickOpenModal from "./QuickOpenModal";
 import WhyPaused from "./SecondaryPanes/WhyPaused";
 
-type OwnProps = {||};
+type OwnProps = {
+  toolboxDoc: Object,
+};
 type Props = {
   selectedSource: ?Source,
   orientation: OrientationType,
   startPanelCollapsed: boolean,
   endPanelCollapsed: boolean,
   activeSearch: ?ActiveSearchType,
   quickOpenEnabled: boolean,
+  toolboxDoc: Object,
   setActiveSearch: typeof actions.setActiveSearch,
   closeActiveSearch: typeof actions.closeActiveSearch,
   closeProjectSearch: typeof actions.closeProjectSearch,
   openQuickOpen: typeof actions.openQuickOpen,
   closeQuickOpen: typeof actions.closeQuickOpen,
   setOrientation: typeof actions.setOrientation,
 };
 
@@ -93,19 +96,23 @@ class App extends Component<Props, State
     super(props);
     this.state = {
       shortcutsModalEnabled: false,
       startPanelSize: 0,
       endPanelSize: 0,
     };
   }
 
-  getChildContext = () => {
-    return { shortcuts, l10n: L10N };
-  };
+  getChildContext() {
+    return {
+      toolboxDoc: this.props.toolboxDoc,
+      shortcuts,
+      l10n: L10N,
+    };
+  }
 
   componentDidMount() {
     horizontalLayoutBreakpoint.addListener(this.onLayoutChange);
     verticalLayoutBreakpoint.addListener(this.onLayoutChange);
     this.setOrientation();
 
     shortcuts.on(L10N.getStr("symbolSearch.search.key2"), (_, e) =>
       this.toggleQuickOpenModal(_, e, "@")
@@ -326,16 +333,17 @@ class App extends Component<Props, State
           {this.renderShortcutsModal()}
         </A11yIntention>
       </div>
     );
   }
 }
 
 App.childContextTypes = {
+  toolboxDoc: PropTypes.object,
   shortcuts: PropTypes.object,
   l10n: PropTypes.object,
 };
 
 const mapStateToProps = state => ({
   selectedSource: getSelectedSource(state),
   startPanelCollapsed: getPaneCollapse(state, "start"),
   endPanelCollapsed: getPaneCollapse(state, "end"),

--- a/devtools/client/debugger/src/components/SecondaryPanes/CommandBar.js
+++ b/devtools/client/debugger/src/components/SecondaryPanes/CommandBar.js
@@ -4,33 +4,40 @@
 
 // @flow
 
 import PropTypes from "prop-types";
 import React, { Component } from "react";
 
 import { connect } from "../../utils/connect";
 import classnames from "classnames";
-import { features } from "../../utils/prefs";
+import { features, javascriptPrefs } from "../../utils/prefs";
 import {
   getIsWaitingOnBreak,
   getSkipPausing,
   getCurrentThread,
   isTopFrameSelected,
   getThreadContext,
 } from "../../selectors";
 import { formatKeyShortcut } from "../../utils/text";
 import actions from "../../actions";
 import { debugBtn } from "../shared/Button/CommandBarButton";
 import AccessibleImage from "../shared/AccessibleImage";
 import "./CommandBar.css";
 
 import { appinfo } from "devtools-services";
 import type { ThreadContext } from "../../types";
 
+// $FlowIgnore
+const MenuButton = require("devtools/client/shared/components/menu/MenuButton");
+// $FlowIgnore
+const MenuItem = require("devtools/client/shared/components/menu/MenuItem");
+// $FlowIgnore
+const MenuList = require("devtools/client/shared/components/menu/MenuList");
+
 const isMacOS = appinfo.OS === "Darwin";
 
 // NOTE: the "resume" command will call either the resume or breakOnNext action
 // depending on whether or not the debugger is paused or running
 const COMMANDS = ["resume", "stepOver", "stepIn", "stepOut"];
 type CommandActionType = "resume" | "stepOver" | "stepIn" | "stepOut";
 
 const KEYS = {
@@ -223,33 +230,67 @@ class CommandBar extends Component<Props
         }
         onClick={toggleSkipPausing}
       >
         <AccessibleImage className="disable-pausing" />
       </button>
     );
   }
 
+  renderSettingsButton() {
+    const { toolboxDoc } = this.context;
+
+    return (
+      <MenuButton
+        menuId="debugger-settings-menu-button"
+        toolboxDoc={toolboxDoc}
+        className="devtools-button command-bar-button debugger-settings-menu-button"
+        title={L10N.getStr("settings.label")}
+      >
+        {() => this.renderSettingsMenuItems()}
+      </MenuButton>
+    );
+  }
+
+  renderSettingsMenuItems() {
+    return (
+      <MenuList id="debugger-settings-menu-list">
+        <MenuItem
+          key="debugger-settings-menu-item-disable-javascript"
+          className="menu-item debugger-settings-menu-item-disable-javascript"
+          checked={!javascriptPrefs.enableJavaScript}
+          label={L10N.getStr("settings.disableJavaScript.label")}
+          tooltip={L10N.getStr("settings.disableJavaScript.tooltip")}
+          onClick={() => {
+            javascriptPrefs.enableJavaScript = !javascriptPrefs.enableJavaScript;
+          }}
+        />
+      </MenuList>
+    );
+  }
+
   render() {
     return (
       <div
         className={classnames("command-bar", {
           vertical: !this.props.horizontal,
         })}
       >
         {this.renderStepButtons()}
         <div className="filler" />
         {this.renderSkipPausingButton()}
+        {this.renderSettingsButton()}
       </div>
     );
   }
 }
 
 CommandBar.contextTypes = {
   shortcuts: PropTypes.object,
+  toolboxDoc: PropTypes.object,
 };
 
 const mapStateToProps = state => ({
   cx: getThreadContext(state),
   isWaitingOnBreak: getIsWaitingOnBreak(state, getCurrentThread(state)),
   skipPausing: getSkipPausing(state),
   topFrameSelected: isTopFrameSelected(state, getCurrentThread(state)),
 });

--- a/devtools/client/debugger/src/components/shared/Button/styles/CommandBarButton.css
+++ b/devtools/client/debugger/src/components/shared/Button/styles/CommandBarButton.css
@@ -14,26 +14,40 @@
   min-width: 30px;
 }
 
 .command-bar-button:disabled {
   opacity: 0.6;
   cursor: default;
 }
 
-.command-bar-button:not(.disabled):hover {
+.command-bar-button:not(.disabled):hover,
+.devtools-button.debugger-settings-menu-button:empty:not(:disabled):not([aria-expanded="true"]):hover {
   background: var(--theme-toolbar-background-hover);
 }
 
-.theme-dark .command-bar-button:not(.disabled):hover {
+.theme-dark .command-bar-button:not(.disabled):hover,
+.devtools-button.debugger-settings-menu-button:empty:not(:disabled):not([aria-expanded="true"]):hover {
   background: var(--theme-toolbar-hover);
 }
 
 :root.theme-dark .command-bar-button {
   color: var(--theme-body-color);
 }
 
 .command-bar-button > * {
   width: 16px;
   height: 16px;
   display: inline-block;
   vertical-align: middle;
 }
+
+/**
+ * Settings icon and menu
+ */
+.devtools-button.debugger-settings-menu-button {
+  border-radius: 0;
+  margin: 0;
+}
+
+.devtools-button.debugger-settings-menu-button::before {
+  background-image: url("chrome://devtools/skin/images/settings.svg");
+}

--- a/devtools/client/debugger/src/main.development.js
+++ b/devtools/client/debugger/src/main.development.js
@@ -28,10 +28,11 @@ bootstrap(React, ReactDOM).then(connecti
     openConsoleAndEvaluate: input => alert(`console.log: ${input}`),
     highlightDomElement: (grip: Object) =>
       console.log("highlighting dom element"),
     unHighlightDomElement: (grip: Object) =>
       console.log("unhighlighting dom element"),
     getToolboxStore: () => {
       throw new Error("Cannot connect to Toolbox store when running Launchpad");
     },
+    panelWin: window,
   });
 });

new file mode 100644
--- /dev/null
+++ b/devtools/client/debugger/src/test/fixtures/Chrome.js
@@ -0,0 +1,10 @@
+/* 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";
+
+module.exports = {
+  Cu: {},
+  components: {},
+};

new file mode 100644
--- /dev/null
+++ b/devtools/client/debugger/src/test/fixtures/ChromeUtils.js
@@ -0,0 +1,7 @@
+/* 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";
+
+module.exports = {};

--- a/devtools/client/debugger/src/test/fixtures/Services.js
+++ b/devtools/client/debugger/src/test/fixtures/Services.js
@@ -1,9 +1,11 @@
 /* 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";
 
 module.exports = {
   appinfo: "",
+  prefs: { getBoolPref: () => {}, addObserver: () => {} },
+  obs: { addObserver: () => {} },
 };

--- a/devtools/client/debugger/src/test/tests-setup.js
+++ b/devtools/client/debugger/src/test/tests-setup.js
@@ -3,17 +3,16 @@
  * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
 
 // @flow
 
 // $FlowIgnore
 global.Worker = require("workerjs");
 
 import path from "path";
-// import getConfig from "../../bin/getConfig";
 import { readFileSync } from "fs";
 import Enzyme from "enzyme";
 // $FlowIgnore
 import Adapter from "enzyme-adapter-react-16";
 import { setupHelper } from "../utils/dbg";
 import { prefs } from "../utils/prefs";
 
 import { startSourceMapWorker, stopSourceMapWorker } from "devtools-source-map";
@@ -46,16 +45,53 @@ function getL10nBundle() {
   }
 }
 
 global.DebuggerConfig = {};
 global.L10N = require("devtools-launchpad").L10N;
 global.L10N.setBundle(getL10nBundle());
 global.jasmine.DEFAULT_TIMEOUT_INTERVAL = 20000;
 global.performance = { now: () => 0 };
+global.isWorker = false;
+
+global.define = function() {};
+global.loader = {
+  lazyServiceGetter: () => {},
+  lazyGetter: (context, name, fn) => {
+    try {
+      global[name] = fn();
+    } catch (_) {}
+  },
+  lazyRequireGetter: (context, name, _path, destruct) => {
+    if (
+      !_path ||
+      _path.startsWith("resource://") ||
+      _path.match(/server\/actors/)
+    ) {
+      return;
+    }
+
+    const excluded = [
+      "Debugger",
+      "devtools/shared/event-emitter",
+      "devtools/client/shared/autocomplete-popup",
+      "devtools/client/framework/devtools",
+      "devtools/client/shared/keycodes",
+      "devtools/client/shared/sourceeditor/editor",
+      "devtools/client/shared/telemetry",
+      "devtools/shared/screenshot/save",
+      "devtools/client/shared/focus",
+    ];
+    if (!excluded.includes(_path)) {
+      // $FlowIgnore
+      const module = require(_path);
+      global[name] = destruct ? module[name] : module;
+    }
+  },
+};
 
 const { URL } = require("url");
 global.URL = URL;
 
 global.indexedDB = mockIndexeddDB();
 
 Enzyme.configure({ adapter: new Adapter() });
 

--- a/devtools/client/debugger/src/utils/bootstrap.js
+++ b/devtools/client/debugger/src/utils/bootstrap.js
@@ -37,24 +37,26 @@ function renderPanel(component, store, p
   root.className = "launchpad-root theme-body";
   root.style.setProperty("flex", "1");
   const mount = document.querySelector("#mount");
   if (!mount) {
     return;
   }
   mount.appendChild(root);
 
+  const toolboxDoc = panel.panelWin.parent.document;
+
   ReactDOM.render(
     React.createElement(
       Provider,
       { store },
       React.createElement(
         ToolboxProvider,
         { store: panel.getToolboxStore() },
-        React.createElement(component)
+        React.createElement(component, { toolboxDoc })
       )
     ),
     root
   );
 }
 
 type Workers = {
   sourceMaps: typeof SourceMaps,

--- a/devtools/client/debugger/src/utils/prefs.js
+++ b/devtools/client/debugger/src/utils/prefs.js
@@ -72,16 +72,17 @@ if (isDevelopment()) {
   pref("devtools.debugger.features.event-listeners-breakpoints", true);
   pref("devtools.debugger.features.dom-mutation-breakpoints", true);
   pref("devtools.debugger.features.log-points", true);
   pref("devtools.debugger.features.inline-preview", true);
   pref("devtools.debugger.features.overlay-step-buttons", true);
   pref("devtools.debugger.features.watchpoints", true);
   pref("devtools.debugger.features.frame-step", true);
   pref("devtools.editor.tabsize", 2);
+  pref("javascript.enabled", true);
 }
 
 export const prefs = new PrefsHelper("devtools", {
   fission: ["Bool", "browsertoolbox.fission"],
   logging: ["Bool", "debugger.logging"],
   editorWrapping: ["Bool", "debugger.ui.editor-wrapping"],
   alphabetizeOutline: ["Bool", "debugger.alphabetize-outline"],
   autoPrettyPrint: ["Bool", "debugger.auto-pretty-print"],
@@ -116,16 +117,20 @@ export const prefs = new PrefsHelper("de
   projectDirectoryRoot: ["Char", "debugger.project-directory-root", ""],
   skipPausing: ["Bool", "debugger.skip-pausing"],
   mapScopes: ["Bool", "debugger.map-scopes-enabled"],
   logActions: ["Bool", "debugger.log-actions"],
   logEventBreakpoints: ["Bool", "debugger.log-event-breakpoints"],
   indentSize: ["Int", "editor.tabsize"],
 });
 
+export const javascriptPrefs = new PrefsHelper("javascript", {
+  enableJavaScript: ["Bool", "enabled"],
+});
+
 // The pref may not be defined. Defaulting to null isn't viable (cursor never blinks).
 // Can't use CodeMirror.defaults here because it's loaded later.
 // Hardcode the fallback value to that of CodeMirror.defaults.cursorBlinkRate.
 prefs.cursorBlinkRate = Services.prefs.getIntPref("ui.caretBlinkTime", 530);
 
 export const features = new PrefsHelper("devtools.debugger.features", {
   asyncStepping: ["Bool", "async-stepping"],
   wasm: ["Bool", "wasm"],

--- a/devtools/client/debugger/test/mochitest/browser.ini
+++ b/devtools/client/debugger/test/mochitest/browser.ini
@@ -198,8 +198,9 @@ skip-if = (os == 'linux' && debug) || (o
 skip-if = debug
 [browser_dbg-toolbox-unselected-pause.js]
 skip-if = asan # Bug 1591064
 [browser_dbg-toolbox-workers.js]
 skip-if = asan || !nightly_build # Bug 1591064, parent intercept mode is needed bug 1588154
 [browser_dbg-wrong-fetch.js]
 [browser_dbg-worker-nested.js]
 [browser_dbg-step-in-navigate.js]
+[browser_dbg-settings-disable-javascript.js]

new file mode 100644
--- /dev/null
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-settings-disable-javascript.js
@@ -0,0 +1,36 @@
+/* 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/>. */
+
+async function toggleJavaScript(dbg, shouldBeCheckedAtStart) {
+  const menuItemClassName = ".debugger-settings-menu-item-disable-javascript";
+
+  const menuButton = findElementWithSelector(dbg, ".debugger-settings-menu-button");
+  menuButton.click();
+
+  // Wait for the menu to show before trying to click the item
+  const { parent } = dbg.panel.panelWin;
+  const { document } = parent;
+
+  const menuItem = document.querySelector(menuItemClassName);
+  is(
+    !!menuItem.getAttribute("aria-checked"), 
+    shouldBeCheckedAtStart,
+    "Item is checked before clicking"
+  );
+  menuItem.click();
+}
+
+// Tests that using the Settings menu to enable and disable JavaScript
+// updates the pref properly
+add_task(async function() {
+  const dbg = await initDebugger("doc-scripts.html", "simple1.js");
+
+  info("Clicking the disable javascript button in the settings menu");
+  await toggleJavaScript(dbg, false);
+  is(Services.prefs.getBoolPref("javascript.enabled"), false, "JavaScript is disabled");
+
+  info("Clicking the disable javascript button in the settings menu to reenable JavaScript");
+  await toggleJavaScript(dbg, true);
+  is(Services.prefs.getBoolPref("javascript.enabled"), true, "JavaScript is enabled");
+});

--- a/devtools/client/debugger/test/mochitest/helpers.js
+++ b/devtools/client/debugger/test/mochitest/helpers.js
@@ -576,16 +576,17 @@ async function clearDebuggerPreferences(
   Services.prefs.clearUserPref("devtools.debugger.ignore-caught-exceptions");
   Services.prefs.clearUserPref("devtools.debugger.pending-selected-location");
   Services.prefs.clearUserPref("devtools.debugger.expressions");
   Services.prefs.clearUserPref("devtools.debugger.breakpoints-visible");
   Services.prefs.clearUserPref("devtools.debugger.call-stack-visible");
   Services.prefs.clearUserPref("devtools.debugger.scopes-visible");
   Services.prefs.clearUserPref("devtools.debugger.skip-pausing");
   Services.prefs.clearUserPref("devtools.debugger.map-scopes-enabled");
+  Services.prefs.clearUserPref("javascript.enabled");
   await pushPref("devtools.debugger.log-actions", true);
   for (const pref of prefs) {
     await pushPref(...pref);
   }
 }
 
 /**
  * Intilializes the debugger.

--- a/devtools/client/locales/en-US/debugger.properties
+++ b/devtools/client/locales/en-US/debugger.properties
@@ -474,16 +474,27 @@ downloadFile.accesskey=d
 # LOCALIZATION NOTE (inlinePreview.show.label): Context menu item
 # for showing the inline preview blocks
 inlinePreview.show.label=Show inline preview
 
 # LOCALIZATION NOTE (inlinePreview.hide.label): Context menu item
 # for hiding the inline preview block
 inlinePreview.hide.label=Hide inline preview
 
+# LOCALIZATION NOTE (settings.label): Label for Settings button
+settings.label=Debugger Settings
+
+# LOCALIZATION NOTE (settings.disableJavaScript.label): Context menu item
+# tooltip for disabling JavaScript
+settings.disableJavaScript.label=Disable JavaScript
+
+# LOCALIZATION NOTE (settings.disableJavaScript.tooltip): Context menu item
+# tooltip for disabling JavaScript
+settings.disableJavaScript.tooltip=Disables JavaScript in the current tab (Requires refresh)
+
 # LOCALIZATION NOTE (preview.noProperties): Label shown in the preview
 # popup when there are no properties to show.
 preview.noProperties=No properties
 
 # LOCALIZATION NOTE (framework.disableGrouping): This is the text that appears in the
 # context menu to disable framework grouping.
 framework.disableGrouping=Disable framework grouping
 framework.disableGrouping.accesskey=u