Index: src/xsprintf/__tests__/PhutilcsprintfTestCase.php
===================================================================
--- src/xsprintf/__tests__/PhutilcsprintfTestCase.php
+++ src/xsprintf/__tests__/PhutilcsprintfTestCase.php
@@ -2,6 +2,20 @@
 
 final class PhutilcsprintfTestCase extends ArcanistTestCase {
 
+  public function testCommandReadableEscapes() {
+    // For arguments comprised of only characters which are safe in any context,
+    // %R this should avoid adding quotes.
+    $this->assertEqual(
+      true,
+      ('ab' === (string)csprintf('%R', 'ab')));
+
+    // For arguments which have any characters which are not safe in some
+    // context, %R should apply standard escaping.
+    $this->assertEqual(
+      false,
+      ('a b' === (string)csprintf('%R', 'a b')));
+  }
+
   public function testPasswords() {
 
     // Normal "%s" doesn't do anything special.
@@ -10,7 +24,6 @@
       true,
       strpos($command, 'hunter2trustno1') !== false);
 
-
     // "%P" takes a PhutilOpaqueEnvelope.
     $caught = null;
     try {
Index: src/xsprintf/csprintf.php
===================================================================
--- src/xsprintf/csprintf.php
+++ src/xsprintf/csprintf.php
@@ -15,6 +15,12 @@
  *   %C (Raw Command)
  *     Passes the argument through without escaping. Dangerous!
  *
+ *   %R
+ *     A more "readable" version of "%s". This will try to print the command
+ *     without any escaping if it contains only characters which are safe
+ *     in any context. The intent is to produce prettier human-readable
+ *     commands.
+ *
  * Generally, you should invoke shell commands via execx() rather than by
  * calling csprintf() directly.
  *
@@ -80,6 +86,12 @@
       // Convert the list of strings to a single string.
       $value = implode(' ', array_map('escapeshellarg', $value));
       break;
+    case 'R':
+      if (!preg_match('(^[a-zA-Z0-9:/@._-]+$)', $value)) {
+        $value = escapeshellarg($value);
+      }
+      $type = 's';
+      break;
     case 's':
       $value = escapeshellarg($value);
       $type = 's';