Index: wp-admin/includes/meta-boxes.php
===================================================================
--- wp-admin/includes/meta-boxes.php	(revision 24727)
+++ wp-admin/includes/meta-boxes.php	(working copy)
@@ -138,7 +138,7 @@
 <span id="sticky-span"><input id="sticky" name="sticky" type="checkbox" value="sticky" <?php checked( is_sticky( $post->ID ) ); ?> /> <label for="sticky" class="selectit"><?php _e( 'Stick this post to the front page' ); ?></label><br /></span>
 <?php endif; ?>
 <input type="radio" name="visibility" id="visibility-radio-password" value="password" <?php checked( $visibility, 'password' ); ?> /> <label for="visibility-radio-password" class="selectit"><?php _e('Password protected'); ?></label><br />
-<span id="password-span"><label for="post_password"><?php _e('Password:'); ?></label> <input type="text" name="post_password" id="post_password" value="<?php echo esc_attr($post->post_password); ?>" /><br /></span>
+<span id="password-span"><label for="post_password"><?php _e('Password:'); ?></label> <input type="text" name="post_password" id="post_password" value="<?php echo esc_attr($post->post_password); ?>"  maxlength="20" /><br /></span>
 <input type="radio" name="visibility" id="visibility-radio-private" value="private" <?php checked( $visibility, 'private' ); ?> /> <label for="visibility-radio-private" class="selectit"><?php _e('Private'); ?></label><br />
 
 <p>