diff --git a/includes/common.inc b/includes/common.inc
index 0437ec1a435..a80792e3260 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -3802,7 +3802,7 @@ function drupal_load_stylesheet_content($contents, $optimize = FALSE) {
 
   // Replaces @import commands with the actual stylesheet content.
   // This happens recursively but omits external files.
-  $contents = preg_replace_callback('/@import\s*(?:url\(\s*)?[\'"]?(?![a-z]+:)([^\'"\()]+)[\'"]?\s*\)?\s*;/', '_drupal_load_stylesheet', $contents);
+  $contents = preg_replace_callback('/@import\s*(?:url\(\s*)?[\'"]?(?![a-z]+:)(?!\/\/)([^\'"\()]+)[\'"]?\s*\)?\s*;/', '_drupal_load_stylesheet', $contents);
   return $contents;
 }
 
diff --git a/modules/simpletest/files/css_test_files/css_input_with_import.css b/modules/simpletest/files/css_test_files/css_input_with_import.css
index 87afcb35f87..484db8375f6 100644
--- a/modules/simpletest/files/css_test_files/css_input_with_import.css
+++ b/modules/simpletest/files/css_test_files/css_input_with_import.css
@@ -1,5 +1,7 @@
 
 
+@import url("http://example.com/style.css");
+@import url("//example.com/style.css");
 @import "import1.css";
 @import "import2.css";
 
diff --git a/modules/simpletest/files/css_test_files/css_input_with_import.css.optimized.css b/modules/simpletest/files/css_test_files/css_input_with_import.css.optimized.css
index a05f939f3eb..a2af7b3682d 100644
--- a/modules/simpletest/files/css_test_files/css_input_with_import.css.optimized.css
+++ b/modules/simpletest/files/css_test_files/css_input_with_import.css.optimized.css
@@ -1,4 +1,4 @@
-ul,select{font:1em/160% Verdana,sans-serif;color:#494949;}.ui-icon{background-image:url(images/icon.png);}.data .double-quote{background-image:url("data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7");}.data .single-quote{background-image:url('data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDACAWGBwYFCAcGhwkIiAmMFA0MCwsMGJGSjpQdGZ6eHJmcG6AkLicgIiuim5woNqirr7EztDOfJri8uDI8LjKzsb/2wBDASIkJDAqMF40NF7GhHCExsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsb/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAb/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFAEBAAAAAAAAAAAAAAAAAAAAAP/EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/AKAAH//Z');}.data .no-quote{background-image:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACEAAAAEAQAAAAAo/mtHAAAAIElEQVQIHWMRnWHwcRNLN8NZ7QYWwT8PlBlYsgqVBRsAankIMw5MtnoAAAAASUVORK5CYII=);}
+@import url("http://example.com/style.css");@import url("//example.com/style.css");ul,select{font:1em/160% Verdana,sans-serif;color:#494949;}.ui-icon{background-image:url(images/icon.png);}.data .double-quote{background-image:url("data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7");}.data .single-quote{background-image:url('data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDACAWGBwYFCAcGhwkIiAmMFA0MCwsMGJGSjpQdGZ6eHJmcG6AkLicgIiuim5woNqirr7EztDOfJri8uDI8LjKzsb/2wBDASIkJDAqMF40NF7GhHCExsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsbGxsb/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAb/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFAEBAAAAAAAAAAAAAAAAAAAAAP/EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/AKAAH//Z');}.data .no-quote{background-image:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACEAAAAEAQAAAAAo/mtHAAAAIElEQVQIHWMRnWHwcRNLN8NZ7QYWwT8PlBlYsgqVBRsAankIMw5MtnoAAAAASUVORK5CYII=);}
 p,select{font:1em/160% Verdana,sans-serif;color:#494949;}
 body{margin:0;padding:0;background:#edf5fa;font:76%/170% Verdana,sans-serif;color:#494949;}.this .is .a .test{font:1em/100% Verdana,sans-serif;color:#494949;}.this
 .is
diff --git a/modules/simpletest/files/css_test_files/css_input_with_import.css.unoptimized.css b/modules/simpletest/files/css_test_files/css_input_with_import.css.unoptimized.css
index b8c7778dad8..bc3c7b644ac 100644
--- a/modules/simpletest/files/css_test_files/css_input_with_import.css.unoptimized.css
+++ b/modules/simpletest/files/css_test_files/css_input_with_import.css.unoptimized.css
@@ -1,5 +1,7 @@
 
 
+@import url("http://example.com/style.css");
+@import url("//example.com/style.css");
 
 ul, select {
   font: 1em/160% Verdana, sans-serif;
diff --git a/modules/simpletest/tests/common.test b/modules/simpletest/tests/common.test
index 0f0347fc4a2..fcc9791a431 100644
--- a/modules/simpletest/tests/common.test
+++ b/modules/simpletest/tests/common.test
@@ -942,6 +942,7 @@ class CascadingStylesheetsUnitTest extends DrupalUnitTestCase {
    * - Proper URLs in imported files. (https://drupal.org/node/265719)
    * - Retain pseudo-selectors. (https://drupal.org/node/460448)
    * - Don't adjust data URIs. (https://drupal.org/node/2142441)
+   * - Files imported from external URLs. (https://drupal.org/node/2014851)
    */
   function testLoadCssBasic() {
     // Array of files to test living in 'simpletest/files/css_test_files/'.