diff --git a/wp-admin/admin-ajax.php b/wp-admin/admin-ajax.php
index 2d073bc63d..65398f182e 100644
--- a/wp-admin/admin-ajax.php
+++ b/wp-admin/admin-ajax.php
@@ -36,6 +36,7 @@ require_once( ABSPATH . 'wp-admin/includes/ajax-actions.php' );
 @header( 'X-Robots-Tag: noindex' );
 
 send_nosniff_header();
+nocache_headers();
 
 do_action( 'admin_init' );
 
diff --git a/wp-admin/includes/media.php b/wp-admin/includes/media.php
index e3a912ac81..2f7f318931 100644
--- a/wp-admin/includes/media.php
+++ b/wp-admin/includes/media.php
@@ -1508,6 +1508,11 @@ $plupload_init = array(
 	'multipart_params' => $post_params
 );
 
+// Multi-file uploading doesn't currently work in iOS Safari,
+// single-file allows the built-in camera to be used as source for images
+if ( wp_is_mobile() )
+	$plupload_init['multi_selection'] = false;
+
 $plupload_init = apply_filters( 'plupload_init', $plupload_init );
 
 ?>
diff --git a/wp-includes/js/media-models.js b/wp-includes/js/media-models.js
index 15129e1cd1..7da7327a1d 100644
--- a/wp-includes/js/media-models.js
+++ b/wp-includes/js/media-models.js
@@ -809,4 +809,9 @@ window.wp = window.wp || {};
 		}
 	});
 
+	// Clean up. Prevents mobile browsers caching
+	$(window).on('unload', function(){
+		window.wp = null;
+	});
+
 }(jQuery));
\ No newline at end of file
diff --git a/wp-includes/media.php b/wp-includes/media.php
index 878941ebbe..1612b80d2e 100644
--- a/wp-includes/media.php
+++ b/wp-includes/media.php
@@ -1254,6 +1254,11 @@ function wp_plupload_default_settings() {
 		'multipart'           => true,
 		'urlstream_upload'    => true,
 	);
+	
+	// Multi-file uploading doesn't currently work in iOS Safari,
+	// single-file allows the built-in camera to be used as source for images
+	if ( wp_is_mobile() )
+		$defaults['multi_selection'] = false;
 
 	$defaults = apply_filters( 'plupload_default_settings', $defaults );