diff --git a/situs.drush.inc b/situs.drush.inc
index 27cbad2..2ad5079 100644
--- a/situs.drush.inc
+++ b/situs.drush.inc
@@ -13,6 +13,7 @@ function situs_drush_command() {
   $options = array(
     'root' => 'The root of the site to build.',
     'make-file' => 'The make file to use for building.',
+    'make-*' => 'Settings to pass on to drush make, "make-" will be strippe off. Eg make-concurrency will set the concurrency flag.',
     'save-files' => 'Comma-separated list of files to save when rebuilding.',
   );
   foreach (situs_plugins() as $info) {
@@ -109,10 +110,14 @@ function drush_situs_build($alias = '') {
     return FALSE;
   }
 
-  $settings = array(
+  $make_options = array(
     'working-copy' => TRUE,
   );
-  $res = drush_invoke_process('@self', 'make', array($makefile, $build_path), $settings, TRUE);
+
+  // Add in custom settings.
+  $make_options += _situs_get_custom_make_options();
+
+  $res = drush_invoke_process('@self', 'make', array($makefile, $build_path), $make_options, TRUE);
 
   if (!$res || $res['error_status'] != 0) {
     return drush_set_error('BUILD_FAILED', dt('Drush Make failed.'));
@@ -403,6 +408,39 @@ function situs_git_pre_build() {
 }
 
 /**
+ * Returns an array of options supplied via make-* options.
+ *
+ * "make-file" is a special case and is excluded.
+ */
+function _situs_get_custom_make_options() {
+  // We are not checking a specific context, so check them in a predefined order
+  // of precedence.
+  $contexts = drush_context_names();
+  $make_options = array();
+  foreach ($contexts as $context_name) {
+    $context = drush_get_context($context_name);
+
+    foreach ($context as $key => $value) {
+      // We're looking for variables prefixed with "make-" (except for
+      // make-file).
+      if ($key != 'make-file' && strpos($key, 'make-') === 0) {
+
+        // Strip off the prefix.
+        $option_key = substr($key, strlen('make-'));
+
+        // We're going through the contexts in prioritized order, so first in
+        // wins.
+        if (!isset($make_options[$option_key])) {
+          $make_options[$option_key] = $value;
+        }
+      }
+    }
+  }
+
+  return $make_options;
+}
+
+/**
  *
  */
 function situs_drush_pre_build() {