--- a/.prettierignore
+++ b/.prettierignore
@@ -25,17 +25,16 @@ mobile/android/app/mobile.js
 mobile/android/installer/mobile-l10n.js
 modules/libpref/init/all.js
 modules/libpref/test/unit/data/testParser.js
 modules/libpref/test/unit/data/testPrefLocked.js
 modules/libpref/test/unit/data/testPrefSticky.js
 modules/libpref/test/unit/extdata/testExt.js
 remote/pref/remote.js
 services/sync/tests/unit/prefs_test_prefs_store.js
-testing/marionette/prefs/marionette.js
 
 # Ignore testing pref files which aren't parsed normally.
 testing/profiles/**/user.js
 
 # Ignore CORS fixtures which require specific resource hashes.
 dom/security/test/sri/script*
 
 # Ignore other DOM fixtures with funky chars.

--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -202,17 +202,16 @@
 #endif
 
 ; Marionette remote control protocol
 #ifdef ENABLE_MARIONETTE
 @RESPATH@/chrome/marionette@JAREXT@
 @RESPATH@/chrome/marionette.manifest
 @RESPATH@/components/marionette.manifest
 @RESPATH@/components/marionette.js
-@RESPATH@/defaults/pref/marionette.js
 #endif
 
 #if defined(ENABLE_TESTS) && defined(MOZ_DEBUG)
 @RESPATH@/components/TestInterfaceJS.js
 @RESPATH@/components/TestInterfaceJS.manifest
 @RESPATH@/components/TestInterfaceJSMaplike.js
 #endif
 

--- a/mobile/android/installer/package-manifest.in
+++ b/mobile/android/installer/package-manifest.in
@@ -270,14 +270,13 @@
 #endif
 
 ; Remote control protocol
 #ifdef ENABLE_MARIONETTE
 @BINPATH@/chrome/marionette@JAREXT@
 @BINPATH@/chrome/marionette.manifest
 @BINPATH@/components/marionette.manifest
 @BINPATH@/components/marionette.js
-@BINPATH@/@PREF_DIR@/marionette.js
 #endif
 
 #ifdef PKG_LOCALE_MANIFEST
 #include @PKG_LOCALE_MANIFEST@
 #endif

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -5756,8 +5756,41 @@ pref("services.sync.engine.passwords.val
 // We won't validate an engine if it has more than this many records on the server.
 pref("services.sync.engine.bookmarks.validation.maxRecords", 1000);
 pref("services.sync.engine.passwords.validation.maxRecords", 1000);
 
 // The maximum number of immediate resyncs to trigger for changes made during
 // a sync.
 pref("services.sync.maxResyncs", 5);
 #endif // MOZ_SERVICES_SYNC
+
+// Marionette is the remote protocol that lets OOP programs communicate with,
+// instrument, and control Gecko.
+
+// Starts and stops the Marionette server.
+pref("marionette.enabled", false);
+
+// Delay server startup until a modal dialogue has been clicked to allow time
+// for user to set breakpoints in the Browser Toolbox.
+pref("marionette.debugging.clicktostart", false);
+
+// Verbosity of Marionette logger repository.
+//
+// Available levels are, in descending order of severity, "trace", "debug",
+// "config", "info", "warn", "error", and "fatal". The value is treated
+// case-insensitively.
+pref("marionette.log.level", "Info");
+
+// Certain log messages that are known to be long are truncated. This
+// preference causes them to not be truncated.
+pref("marionette.log.truncate", true);
+
+// Port to start Marionette server on.
+pref("marionette.port", 2828);
+
+// Sets recommended automation preferences when Marionette is started.
+pref("marionette.prefs.recommended", true);
+
+// Whether content scripts can be safely reused.
+//
+// Deprecated and scheduled for removal with
+// https://bugzil.la/marionette-window-tracking
+pref("marionette.contentListener", false);

--- a/testing/marionette/moz.build
+++ b/testing/marionette/moz.build
@@ -1,16 +1,15 @@
 # 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/.
 
 DIRS += ["components"]
 
 JAR_MANIFESTS += ["jar.mn"]
-JS_PREFERENCE_FILES += ["prefs/marionette.js"]
 
 MARIONETTE_UNIT_MANIFESTS += ["harness/marionette_harness/tests/unit/unit-tests.ini"]
 XPCSHELL_TESTS_MANIFESTS += ["test/unit/xpcshell.ini"]
 
 with Files("**"):
     BUG_COMPONENT = ("Testing", "Marionette")
 
 with Files("harness/**"):

deleted file mode 100644
--- a/testing/marionette/prefs/marionette.js
+++ /dev/null
@@ -1,38 +0,0 @@
-/* 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/. */
-
-/* global pref */
-
-// Marionette is the remote protocol that lets OOP programs
-// communicate with, instrument, and control Gecko.
-
-// Starts and stops the Marionette server.
-pref("marionette.enabled", false);
-
-// Delay server startup until a modal dialogue has been clicked to
-// allow time for user to set breakpoints in the Browser Toolbox.
-pref("marionette.debugging.clicktostart", false);
-
-// Verbosity of Marionette logger repository.
-//
-// Available levels are, in descending order of severity,
-// "trace", "debug", "config", "info", "warn", "error", and "fatal".
-// The value is treated case-insensitively.
-pref("marionette.log.level", "Info");
-
-// Certain log messages that are known to be long are truncated.
-// This preference causes them to not be truncated.
-pref("marionette.log.truncate", true);
-
-// Port to start Marionette server on.
-pref("marionette.port", 2828);
-
-// Sets recommended automation preferences when Marionette is started.
-pref("marionette.prefs.recommended", true);
-
-// Whether content scripts can be safely reused.
-//
-// Deprecated and scheduled for removal
-// with https://bugzil.la/marionette-window-tracking
-pref("marionette.contentListener", false);