--- a/toolkit/modules/AppConstants.jsm
+++ b/toolkit/modules/AppConstants.jsm
@@ -353,23 +353,16 @@ this.AppConstants = Object.freeze({
 
   HAVE_SHELL_SERVICE:
 #ifdef HAVE_SHELL_SERVICE
     true,
 #else
     false,
 #endif
 
-  MOZ_PHOTON_PREFERENCES:
-#ifdef MOZ_PHOTON_PREFERENCES
-    true,
-#else
-    false,
-#endif
-
   MOZ_STYLO:
 #ifdef MOZ_STYLO
     true,
 #else
     false,
 #endif
 
 });

--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@@ -505,28 +505,16 @@ project_flag('MOZ_SERVICES_SYNC',
 project_flag('MOZ_ANDROID_HISTORY',
              help='Enable Android History instead of Places',
              set_as_define=True)
 
 project_flag('MOZ_ALLOW_LEGACY_EXTENSIONS',
              help='Allow legacy browser extensions',
              default=True, set_as_define=True)
 
-option(env='MOZ_PHOTON_PREFERENCES',
-       help='Enable Photon preferences',
-       default=milestone.is_nightly)
-
-@depends('MOZ_PHOTON_PREFERENCES')
-def photon_preferences(value):
-    if value:
-        return bool(value)
-
-set_config('MOZ_PHOTON_PREFERENCES', photon_preferences)
-set_define('MOZ_PHOTON_PREFERENCES', photon_preferences)
-
 @depends('MOZ_PLACES', 'MOZ_ANDROID_HISTORY')
 def check_places_and_android_history(places, android_history):
     if places and android_history:
         die('Cannot use MOZ_ANDROID_HISTORY alongside MOZ_PLACES.')
 
 # Permissions system
 # ==============================================================
 option(name='--disable-permissions',