diff --git a/.eslintignore b/.eslintignore
index fca8c2651f54..c1f0da558791 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -220,3 +220,6 @@ tools/tryselect/selectors/chooser/templates/chooser.html
 
 # Ignore preprocessed *(P)refs.js files in update-packaging.
 tools/update-packaging/**/*refs.js
+
+# Ignore backgroundtasks preferences files.
+toolkit/components/backgroundtasks/defaults
diff --git a/.prettierignore b/.prettierignore
index 24fd18b7f33f..c4b4c32638c9 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -58,3 +58,6 @@ devtools/client/debugger/src/test/mochitest/examples/ember/quickstart
 
 # These are source mapped and the locations are asserted in the test case.
 devtools/client/webconsole/test/browser/test-mangled-function.*
+
+# Ignore backgroundtasks preferences files.
+toolkit/components/backgroundtasks/defaults
diff --git a/browser/base/content/test/static/browser_all_files_referenced.js b/browser/base/content/test/static/browser_all_files_referenced.js
index eb9a7fcd4579..7b20d7d34502 100644
--- a/browser/base/content/test/static/browser_all_files_referenced.js
+++ b/browser/base/content/test/static/browser_all_files_referenced.js
@@ -56,6 +56,8 @@ if (AppConstants.platform == "macosx") {
 }
 
 if (AppConstants.MOZ_BACKGROUNDTASKS) {
+  // These preferences are active only when we're in background task mode.
+  gExceptionPaths.push("resource://gre/defaults/backgroundtasks/");
   // `BackgroundTask_id.jsm` is loaded at runtime by `app --backgroundtask id ...`.
   gExceptionPaths.push("resource://gre/modules/backgroundtasks/");
 }
diff --git a/browser/installer/Makefile.in b/browser/installer/Makefile.in
index b861ad214a64..ad725c5114b0 100644
--- a/browser/installer/Makefile.in
+++ b/browser/installer/Makefile.in
@@ -98,6 +98,10 @@ ifdef MOZ_DEFAULT_BROWSER_AGENT
 DEFINES += -DMOZ_DEFAULT_BROWSER_AGENT=1
 endif
 
+ifdef MOZ_BACKGROUNDTASKS
+DEFINES += -DMOZ_BACKGROUNDTASKS=1
+endif
+
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 MOZ_PKG_MAC_DSSTORE=$(topsrcdir)/$(MOZ_BRANDING_DIRECTORY)/dsstore
 MOZ_PKG_MAC_BACKGROUND=$(topsrcdir)/$(MOZ_BRANDING_DIRECTORY)/background.png
diff --git a/browser/installer/package-manifest.in b/browser/installer/package-manifest.in
index f060c457cee2..ec20499166e8 100644
--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -305,6 +305,12 @@
 ; gre location for now.
 @RESPATH@/defaults/pref/channel-prefs.js
 
+; Background tasks-specific preferences.  These are in the GRE
+; location since they apply to all tasks at this time.
+#ifdef MOZ_BACKGROUNDTASKS
+@RESPATH@/defaults/backgroundtasks/backgroundtasks.js
+#endif
+
 ; [Layout Engine Resources]
 ; Style Sheets, Graphics and other Resources used by the layout engine.
 @RESPATH@/res/EditorOverride.css
diff --git a/modules/libpref/Preferences.cpp b/modules/libpref/Preferences.cpp
index cfc498d5c250..2a7f5bacbd83 100644
--- a/modules/libpref/Preferences.cpp
+++ b/modules/libpref/Preferences.cpp
@@ -86,6 +86,9 @@
 #include "plstr.h"
 #include "prlink.h"
 #include "xpcpublic.h"
+#ifdef MOZ_BACKGROUNDTASKS
+#  include "mozilla/BackgroundTasks.h"
+#endif
 
 #ifdef DEBUG
 #  include <map>
@@ -4530,6 +4533,13 @@ nsresult Preferences::InitInitialObjects(bool aIsStartup) {
     rv = pref_ReadDefaultPrefs(jarReader, "defaults/pref/*.js$");
     NS_ENSURE_SUCCESS(rv, rv);
 
+#ifdef MOZ_BACKGROUNDTASKS
+    if (BackgroundTasks::IsBackgroundTaskMode()) {
+      rv = pref_ReadDefaultPrefs(jarReader, "defaults/backgroundtasks/*.js$");
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+#endif
+
 #ifdef MOZ_WIDGET_ANDROID
     // Load jar:$gre/omni.jar!/defaults/pref/$MOZ_ANDROID_CPU_ABI/*.js.
     nsAutoCString path;
@@ -4609,6 +4619,25 @@ nsresult Preferences::InitInitialObjects(bool aIsStartup) {
         NS_WARNING("Error parsing preferences.");
       }
     }
+
+#ifdef MOZ_BACKGROUNDTASKS
+    if (BackgroundTasks::IsBackgroundTaskMode()) {
+      rv = appJarReader->FindInit("defaults/backgroundtasks/*.js$",
+                                  getter_Transfers(find));
+      NS_ENSURE_SUCCESS(rv, rv);
+      prefEntries.Clear();
+      while (NS_SUCCEEDED(find->FindNext(&entryName, &entryNameLen))) {
+        prefEntries.AppendElement(Substring(entryName, entryNameLen));
+      }
+      prefEntries.Sort();
+      for (uint32_t i = prefEntries.Length(); i--;) {
+        rv = pref_ReadPrefFromJar(appJarReader, prefEntries[i].get());
+        if (NS_FAILED(rv)) {
+          NS_WARNING("Error parsing preferences.");
+        }
+      }
+    }
+#endif
   }
 
   nsCOMPtr<nsIProperties> dirSvc(
diff --git a/modules/libpref/moz.build b/modules/libpref/moz.build
index 9273ab29dc99..d0ccfcff6609 100644
--- a/modules/libpref/moz.build
+++ b/modules/libpref/moz.build
@@ -167,3 +167,6 @@ else:
     FINAL_TARGET_PP_FILES += [
         "greprefs.js",
     ]
+
+if CONFIG["MOZ_BACKGROUNDTASKS"]:
+    DEFINES["MOZ_BACKGROUNDTASKS"] = True
diff --git a/toolkit/components/backgroundtasks/defaults/backgroundtasks.js b/toolkit/components/backgroundtasks/defaults/backgroundtasks.js
new file mode 100644
index 000000000000..a52c1b117873
--- /dev/null
+++ b/toolkit/components/backgroundtasks/defaults/backgroundtasks.js
@@ -0,0 +1,27 @@
+/* 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/. */
+
+pref("browser.dom.window.dump.enabled", true);
+pref("devtools.console.stdout.chrome", true);
+
+pref("network.process.enabled", false);
+
+pref("toolkit.telemetry.archive.enabled", false);
+pref("toolkit.telemetry.firstShutdownPing.enabled", false);
+pref("toolkit.telemetry.healthping.enabled", false);
+pref("toolkit.telemetry.newProfilePing.enabled", false);
+pref("toolkit.telemetry.eventping.enabled", false);
+pref("toolkit.telemetry.ecosystemtelemetry.enabled", false);
+pref("toolkit.telemetry.prioping.enabled", false);
+pref("datareporting.policy.dataSubmissionEnabled", false);
+pref("datareporting.healthreport.uploadEnabled", false);
+
+pref("browser.cache.offline.enable", false);
+pref("browser.cache.offline.storage.enable", false);
+pref("browser.cache.disk.enable", false);
+pref("permissions.memory_only", true);
+
+// For testing only: used to test that backgroundtask-specific prefs are
+// processed.  This just needs to be an unusual integer in the range 0..127.
+pref("test.backgroundtask_specific_pref.exitCode", 79);
diff --git a/toolkit/components/backgroundtasks/moz.build b/toolkit/components/backgroundtasks/moz.build
index 9173bdced63c..39bd3bd04f81 100644
--- a/toolkit/components/backgroundtasks/moz.build
+++ b/toolkit/components/backgroundtasks/moz.build
@@ -37,4 +37,13 @@ EXTRA_JS_MODULES.backgroundtasks += [
     "BackgroundTask_success.jsm",
 ]
 
+BROWSER_CHROME_MANIFESTS += ["tests/browser/browser.ini"]
 XPCSHELL_TESTS_MANIFESTS += ["tests/xpcshell/xpcshell.ini"]
+
+TESTING_JS_MODULES.backgroundtasks += [
+    "tests/BackgroundTask_backgroundtask_specific_pref.jsm",
+]
+
+FINAL_TARGET_FILES.defaults.backgroundtasks += [
+    "defaults/backgroundtasks.js",
+]
diff --git a/toolkit/components/backgroundtasks/tests/BackgroundTask_backgroundtask_specific_pref.jsm b/toolkit/components/backgroundtasks/tests/BackgroundTask_backgroundtask_specific_pref.jsm
new file mode 100644
index 000000000000..0fa900f04f5e
--- /dev/null
+++ b/toolkit/components/backgroundtasks/tests/BackgroundTask_backgroundtask_specific_pref.jsm
@@ -0,0 +1,23 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * 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/. */
+
+var EXPORTED_SYMBOLS = ["runBackgroundTask"];
+
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+async function runBackgroundTask(commandLine) {
+  let pref = commandLine.length
+    ? commandLine.getArgument(0)
+    : "test.backgroundtask_specific_pref.exitCode";
+
+  // 0, 1, 2, 3 are all meaningful exit codes already.
+  let exitCode = Services.prefs.getIntPref(pref, 4);
+
+  console.error(
+    `runBackgroundTask: backgroundtask_specific_pref read pref '${pref}', exiting with exitCode ${exitCode}`
+  );
+
+  return exitCode;
+}
diff --git a/toolkit/components/backgroundtasks/tests/browser/browser.ini b/toolkit/components/backgroundtasks/tests/browser/browser.ini
new file mode 100644
index 000000000000..aed80c744448
--- /dev/null
+++ b/toolkit/components/backgroundtasks/tests/browser/browser.ini
@@ -0,0 +1,9 @@
+# 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/.
+
+[DEFAULT]
+skip-if = toolkit == 'android'
+head = head.js
+
+[browser_backgroundtask_specific_pref.js]
diff --git a/toolkit/components/backgroundtasks/tests/browser/browser_backgroundtask_specific_pref.js b/toolkit/components/backgroundtasks/tests/browser/browser_backgroundtask_specific_pref.js
new file mode 100644
index 000000000000..b80ee2f59376
--- /dev/null
+++ b/toolkit/components/backgroundtasks/tests/browser/browser_backgroundtask_specific_pref.js
@@ -0,0 +1,23 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * vim: sw=4 ts=4 sts=4 et
+ * 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";
+
+add_task(async function test_backgroundtask_specific_pref() {
+  // First, verify this pref isn't set in Gecko itself.
+  Assert.equal(
+    -1,
+    Services.prefs.getIntPref("test.backgroundtask_specific_pref.exitCode", -1)
+  );
+
+  // Second, verify that this pref is set in background tasks.
+  // mochitest-chrome tests locally test both unpackaged and packaged
+  // builds (with `--appname=dist`).
+  let exitCode = await do_backgroundtask("backgroundtask_specific_pref", {
+    extraArgs: ["test.backgroundtask_specific_pref.exitCode"],
+  });
+  Assert.equal(79, exitCode);
+});
diff --git a/toolkit/components/backgroundtasks/tests/browser/head.js b/toolkit/components/backgroundtasks/tests/browser/head.js
new file mode 100644
index 000000000000..fb9c3fe123a0
--- /dev/null
+++ b/toolkit/components/backgroundtasks/tests/browser/head.js
@@ -0,0 +1,66 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * vim: sw=4 ts=4 sts=4 et
+ * 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";
+
+async function do_backgroundtask(
+  task,
+  options = { extraArgs: [], extraEnv: {} }
+) {
+  options = Object.assign({}, options);
+  options.extraArgs = options.extraArgs || [];
+  options.extraEnv = options.extraEnv || {};
+
+  let command = Services.dirsvc.get("XREExeF", Ci.nsIFile).path;
+  let args = ["--backgroundtask", task];
+  args.push(...options.extraArgs);
+
+  // Ensure `resource://testing-common` gets mapped.
+  let protocolHandler = Services.io
+    .getProtocolHandler("resource")
+    .QueryInterface(Ci.nsIResProtocolHandler);
+
+  let uri = protocolHandler.getSubstitution("testing-common");
+  Assert.ok(uri, "resource://testing-common is not substituted");
+
+  // The equivalent of _TESTING_MODULES_DIR in xpcshell.
+  options.extraEnv.XPCSHELL_TESTING_MODULES_URI = uri.spec;
+
+  // Now we can actually invoke the process.
+  info(
+    `launching child process ${command} with args: ${args} and extra environment: ${JSON.stringify(
+      options.extraEnv
+    )}`
+  );
+
+  const { Subprocess } = ChromeUtils.import(
+    "resource://gre/modules/Subprocess.jsm"
+  );
+  let proc = await Subprocess.call({
+    command,
+    arguments: args,
+    environment: options.extraEnv,
+    environmentAppend: true,
+    stderr: "stdout",
+  }).then(p => {
+    p.stdin.close();
+    const dumpPipe = async pipe => {
+      let data = await pipe.readString();
+      while (data) {
+        for (let line of data.split(/\r\n|\r|\n/).slice(0, -1)) {
+          dump("> " + line + "\n");
+        }
+        data = await pipe.readString();
+      }
+    };
+    dumpPipe(p.stdout);
+
+    return p;
+  });
+
+  let { exitCode } = await proc.wait();
+  return exitCode;
+}
diff --git a/toolkit/components/backgroundtasks/tests/xpcshell/test_backgroundtask_specific_pref.js b/toolkit/components/backgroundtasks/tests/xpcshell/test_backgroundtask_specific_pref.js
new file mode 100644
index 000000000000..50f85b9becb7
--- /dev/null
+++ b/toolkit/components/backgroundtasks/tests/xpcshell/test_backgroundtask_specific_pref.js
@@ -0,0 +1,20 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * vim: sw=4 ts=4 sts=4 et
+ * 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/. */
+
+add_task(async function test_backgroundtask_specific_pref() {
+  // First, verify this pref isn't set in Gecko itself.
+  Assert.equal(
+    -1,
+    Services.prefs.getIntPref("test.backgroundtask_specific_pref.exitCode", -1)
+  );
+
+  // Second, verify that this pref is set in background tasks.
+  // xpcshell tests locally test unpackaged builds.
+  let exitCode = await do_backgroundtask("backgroundtask_specific_pref", {
+    extraArgs: ["test.backgroundtask_specific_pref.exitCode"],
+  });
+  Assert.equal(79, exitCode);
+});
diff --git a/toolkit/components/backgroundtasks/tests/xpcshell/xpcshell.ini b/toolkit/components/backgroundtasks/tests/xpcshell/xpcshell.ini
index ea3f4f118e86..2dd493b2d678 100644
--- a/toolkit/components/backgroundtasks/tests/xpcshell/xpcshell.ini
+++ b/toolkit/components/backgroundtasks/tests/xpcshell/xpcshell.ini
@@ -8,5 +8,6 @@ support-files =
   CatBackgroundTaskRegistrationComponents.manifest
 
 [test_backgroundtask_exitcodes.js]
+[test_backgroundtask_specific_pref.js]
 [test_manifest_with_backgroundtask.js]
 [test_manifest_without_backgroundtask.js]
diff --git a/toolkit/xre/nsXREDirProvider.cpp b/toolkit/xre/nsXREDirProvider.cpp
index 59ec6e0510fa..c9ba0f294cb2 100644
--- a/toolkit/xre/nsXREDirProvider.cpp
+++ b/toolkit/xre/nsXREDirProvider.cpp
@@ -853,6 +853,10 @@ static nsresult DeleteDirIfExists(nsIFile* dir) {
 
 static const char* const kAppendPrefDir[] = {"defaults", "preferences",
                                              nullptr};
+#ifdef MOZ_BACKGROUNDTASKS
+static const char* const kAppendBackgroundTasksPrefDir[] = {
+    "defaults", "backgroundtasks", nullptr};
+#endif
 
 nsresult nsXREDirProvider::GetFilesInternal(const char* aProperty,
                                             nsISimpleEnumerator** aResult) {
@@ -863,6 +867,12 @@ nsresult nsXREDirProvider::GetFilesInternal(const char* aProperty,
     nsCOMArray<nsIFile> directories;
 
     LoadDirIntoArray(mXULAppDir, kAppendPrefDir, directories);
+#ifdef MOZ_BACKGROUNDTASKS
+    if (mozilla::BackgroundTasks::IsBackgroundTaskMode()) {
+      LoadDirIntoArray(mGREDir, kAppendBackgroundTasksPrefDir, directories);
+      LoadDirIntoArray(mXULAppDir, kAppendBackgroundTasksPrefDir, directories);
+    }
+#endif
 
     rv = NS_NewArrayEnumerator(aResult, directories, NS_GET_IID(nsIFile));
   } else if (!strcmp(aProperty, NS_APP_CHROME_DIR_LIST)) {