--- a/toolkit/components/extensions/parent/ext-privacy.js
+++ b/toolkit/components/extensions/parent/ext-privacy.js
@@ -13,16 +13,17 @@ var {
 
 const cookieSvc = Ci.nsICookieService;
 
 const cookieBehaviorValues = new Map([
   ["allow_all", cookieSvc.BEHAVIOR_ACCEPT],
   ["reject_third_party", cookieSvc.BEHAVIOR_REJECT_FOREIGN],
   ["reject_all", cookieSvc.BEHAVIOR_REJECT],
   ["allow_visited", cookieSvc.BEHAVIOR_LIMIT_FOREIGN],
+  ["reject_trackers", cookieSvc.BEHAVIOR_REJECT_TRACKER],
 ]);
 
 const checkScope = scope => {
   if (scope && scope !== "regular") {
     throw new ExtensionError(
       `Firefox does not support the ${scope} settings scope.`);
   }
 };

--- a/toolkit/components/extensions/schemas/privacy.json
+++ b/toolkit/components/extensions/schemas/privacy.json
@@ -77,17 +77,18 @@
         "properties": {
           "behavior": {
             "type": "string",
             "optional": true,
             "enum": [
               "allow_all",
               "reject_all",
               "reject_third_party",
-              "allow_visited"
+              "allow_visited",
+              "reject_trackers"
             ],
             "description": "The type of cookies to allow."
           },
           "nonPersistentCookies": {
             "type": "boolean",
             "optional": true,
             "default": false,
             "description": "Whether to create all cookies as nonPersistent (i.e., session) cookies."

--- a/toolkit/components/extensions/test/xpcshell/test_ext_privacy.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_privacy.js
@@ -242,16 +242,40 @@ add_task(async function test_privacy_oth
       "privacy.firstparty.isolate": true,
     },
     "websites.cookieConfig": {
       "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
     },
   };
 
+  let defaultPrefs = new Preferences({defaultBranch: true});
+  let defaultCookieBehavior = defaultPrefs.get("network.cookie.cookieBehavior");
+  let defaultBehavior;
+  switch (defaultCookieBehavior) {
+    case cookieSvc.BEHAVIOR_ACCEPT:
+      defaultBehavior = "allow_all";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT_FOREIGN:
+      defaultBehavior = "reject_third_party";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT:
+      defaultBehavior = "reject_all";
+      break;
+    case cookieSvc.BEHAVIOR_LIMIT_FOREIGN:
+      defaultBehavior = "allow_visited";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT_TRACKER:
+      defaultBehavior = "reject_trackers";
+      break;
+    default:
+      ok(false, `Unexpected cookie behavior encountered: ${defaultCookieBehavior}`);
+      break;
+  }
+
   async function background() {
     browser.test.onMessage.addListener(async (msg, ...args) => {
       let data = args[0];
       // The second argument is the end of the api name,
       // e.g., "network.webRTCIPHandlingPolicy".
       let apiObj = args[1].split(".").reduce((o, i) => o[i], browser.privacy);
       let settingData;
       switch (msg) {
@@ -422,20 +446,20 @@ add_task(async function test_privacy_oth
     },
     {behavior: "reject_third_party", nonPersistentCookies: false},
   );
   // A missing behavior property should reset the pref.
   await testSetting(
     "websites.cookieConfig",
     {nonPersistentCookies: true},
     {
-      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_SESSION,
     },
-    {behavior: "allow_all", nonPersistentCookies: true},
+    {behavior: defaultBehavior, nonPersistentCookies: true},
   );
   await testSetting(
     "websites.cookieConfig",
     {behavior: "reject_all"},
     {
       "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT,
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
     },
@@ -458,30 +482,40 @@ add_task(async function test_privacy_oth
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
     },
     {behavior: "allow_all", nonPersistentCookies: false},
   );
   await testSetting(
     "websites.cookieConfig",
     {nonPersistentCookies: true},
     {
-      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_SESSION,
     },
-    {behavior: "allow_all", nonPersistentCookies: true},
+    {behavior: defaultBehavior, nonPersistentCookies: true},
   );
   await testSetting(
     "websites.cookieConfig",
     {nonPersistentCookies: false},
     {
-      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
       "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
     },
-    {behavior: "allow_all", nonPersistentCookies: false},
+    {behavior: defaultBehavior, nonPersistentCookies: false},
   );
+  await testSetting(
+    "websites.cookieConfig",
+    {behavior: "reject_trackers"},
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT_TRACKER,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    {behavior: "reject_trackers", nonPersistentCookies: false},
+  );
+
 
   await extension.unload();
 
   await promiseShutdownManager();
 });
 
 add_task(async function test_exceptions() {
   async function background() {