diff --git a/src/applications/config/option/PhabricatorTranslationsConfigOptions.php b/src/applications/config/option/PhabricatorTranslationsConfigOptions.php
index c82e7901bc..e4b624c385 100644
--- a/src/applications/config/option/PhabricatorTranslationsConfigOptions.php
+++ b/src/applications/config/option/PhabricatorTranslationsConfigOptions.php
@@ -32,6 +32,16 @@ final class PhabricatorTranslationsConfigOptions
         ->addExample(
           '{"some string": "my alternative"}',
           pht('Valid Setting')),
+      // Ideally this would be an enum but it can't be because of bootstrapping
+      // problems - this code runs before extensions load, so if we load
+      // locales now to populate the enum then locales defined by extensions
+      // wouldn't load.
+      $this->newOption('locale.command', 'string', 'en_US')
+        ->setSummary(pht('Locale code of command-line locale.'))
+        ->setDescription(pht(
+          'What locale to use for command-line scripts that '.
+          'don\'t specify a `%s` argument.',
+          '--locale')),
     );
   }
 
diff --git a/src/infrastructure/env/PhabricatorEnv.php b/src/infrastructure/env/PhabricatorEnv.php
index 04f6b632e6..4436be2100 100644
--- a/src/infrastructure/env/PhabricatorEnv.php
+++ b/src/infrastructure/env/PhabricatorEnv.php
@@ -69,6 +69,16 @@ final class PhabricatorEnv extends Phobject {
    */
   public static function initializeWebEnvironment() {
     self::initializeCommonEnvironment(false, false);
+
+    // Set up en_US locale for now so that, for instance, if you haven't
+    // set up your database at all it says "Run this command" rather than
+    // "Run these 1 command(s)"
+    // If there aren't any setup problems, then this will get overwritten with
+    // the logged-in user's locale or the locale specified in global default
+    // settings by PhabricatorAuthSessionEngine::willServeRequestForUser
+    // which is called from PhabricatorController:willBeginExecution
+    self::setLocaleCode('en_US');
+
   }
 
   public static function initializeScriptEnvironment(
@@ -76,6 +86,13 @@ final class PhabricatorEnv extends Phobject {
     $no_extensions) {
     self::initializeCommonEnvironment($config_optional, $no_extensions);
 
+    // Set the default locale for command-line scripts
+    self::setLocaleCode(self::getEnvConfig('locale.command'));
+
+    // If a script has a --locale argument then go through our system for
+    // setting locales
+    PhutilArgumentParser::setLocaleCallback(array(__CLASS__, 'setLocaleCode'));
+
     // NOTE: This is dangerous in general, but we know we're in a script context
     // and are not vulnerable to CSRF.
     AphrontWriteGuard::allowDangerousUnguardedWrites(true);
@@ -136,10 +153,6 @@ final class PhabricatorEnv extends Phobject {
 
     PhabricatorEventEngine::initialize();
 
-    // TODO: Add a "locale.default" config option once we have some reasonable
-    // defaults which aren't silly nonsense.
-    self::setLocaleCode('en_US');
-
     // Load the preamble utility library if we haven't already. On web
     // requests this loaded earlier, but we want to load it for non-web
     // requests so that unit tests can call these functions.