diff --git a/includes/install.inc b/includes/install.inc
index 6f876b2c3889401aa062354a12fc541fe3440e41..d1496fcbd480b9443d0fc6bdac7033b20e50f938 100644
--- a/includes/install.inc
+++ b/includes/install.inc
@@ -535,52 +535,6 @@ function drupal_verify_profile($install_state) {
   return $requirements;
 }
 
-/**
- * Calls the install function for a given list of modules.
- *
- * @param $module_list
- *   The modules to install.
- * @param $disable_modules_installed_hook
- *   Normally just testing wants to set this to TRUE.
- * 
- * @return
- *   TRUE if installation was attempted, FALSE if one or more dependencies are
- *   missing.
- */
-function drupal_install_modules($module_list = array(), $disable_modules_installed_hook = FALSE) {
-  $files = system_rebuild_module_data();
-  $module_list = array_flip(array_values($module_list));
-  do {
-    $moved = FALSE;
-    foreach ($module_list as $module => $weight) {
-      $file = $files[$module];
-      if (isset($file->info['dependencies']) && is_array($file->info['dependencies'])) {
-        foreach ($file->info['dependencies'] as $dependency) {
-          if (!isset($module_list[$dependency])) {
-            if (!isset($files[$dependency])) {
-              // A dependency was not found, abort installation.
-              return FALSE;
-            }
-            elseif (!$files[$dependency]->status) {
-              // Add dependencies to $module_list and install them first.
-              $module_list[$dependency] = $weight - 1;
-              $moved = TRUE;
-            }
-          }
-          elseif ($module_list[$module] < $module_list[$dependency] +1) {
-            $module_list[$module] = $module_list[$dependency] +1;
-            $moved = TRUE;
-          }
-        }
-      }
-    }
-  } while ($moved);
-  asort($module_list);
-  $module_list = array_keys($module_list);
-  module_enable($module_list, $disable_modules_installed_hook);
-  return TRUE;
-}
-
 /**
  * Callback to install an individual install profile module.
  *
diff --git a/includes/module.inc b/includes/module.inc
index f440858a843025daeaec6a651cab96db750ffdf5..25b33011a8393cf3a4984ea494e3cd2c93755f08 100644
--- a/includes/module.inc
+++ b/includes/module.inc
@@ -287,10 +287,53 @@ function module_load_all_includes($type, $name = NULL) {
  *
  * @param $module_list
  *   An array of module names.
+ * @param $enable_dependencies
+ *   If TRUE, dependencies will automatically be added and enabled in the
+ *   correct order. This incurs a significant performance cost, so use FALSE
+ *   if you know $module_list is already complete and in the correct order.
  * @param $disable_modules_installed_hook
  *   Normally just testing wants to set this to TRUE.
+ * @return
+ *   FALSE if one or more dependencies are missing, TRUE otherwise.
  */
-function module_enable($module_list, $disable_modules_installed_hook = FALSE) {
+function module_enable($module_list, $enable_dependencies = TRUE, $disable_modules_installed_hook = FALSE) {
+  if ($enable_dependencies) {
+    // Get all module data so we can find dependencies and sort.
+    $module_data = system_rebuild_module_data();
+    // Create an associative array with weights as values.
+    $module_list = array_flip(array_values($module_list));
+
+    while (list($module) = each($module_list)) {
+      if (!isset($module_data[$module])) {
+        // This module is not found in the filesystem, abort.
+        return FALSE;
+      }
+      if ($module_data[$module]->status) {
+        // Skip already enabled modules.
+        unset($module_list[$module]);
+        continue;
+      }
+      $module_list[$module] = $module_data[$module]->sort;
+
+      // Add dependencies to the list, with a placeholder weight.
+      // The new modules will be processed as the while loop continues.
+      foreach ($module_data[$module]->info['dependencies'] as $dependency) {
+        if (!isset($module_list[$dependency])) {
+          $module_list[$dependency] = 0;
+        }
+      }
+    }
+
+    if (!$module_list) {
+      // Nothing to do. All modules already enabled.
+      return TRUE;
+    }
+
+    // Sort the module list by pre-calculated weights.
+    arsort($module_list);
+    $module_list = array_keys($module_list);
+  }
+
   $invoke_modules = array();
 
   // Try to install the enabled modules and collect which were installed.
@@ -328,6 +371,7 @@ function module_enable($module_list, $disable_modules_installed_hook = FALSE) {
     if (!$disable_modules_installed_hook && !empty($modules_installed)) {
       module_invoke_all('modules_installed', $modules_installed);
     }
+    _system_update_bootstrap_status();
   }
 
   foreach ($invoke_modules as $module) {
@@ -346,6 +390,8 @@ function module_enable($module_list, $disable_modules_installed_hook = FALSE) {
     // enabled.
     module_invoke_all('modules_enabled', $invoke_modules);
   }
+
+  return TRUE;
 }
 
 /**
@@ -353,9 +399,42 @@ function module_enable($module_list, $disable_modules_installed_hook = FALSE) {
  *
  * @param $module_list
  *   An array of module names.
+ * @param $disable_dependents
+ *   If TRUE, dependent modules will automatically be added and disabled in the
+ *   correct order. This incurs a significant performance cost, so use FALSE
+ *   if you know $module_list is already complete and in the correct order.
  */
-function module_disable($module_list) {
+function module_disable($module_list, $disable_dependents = TRUE) {
+  if ($disable_dependents) {
+    // Get all module data so we can find dependents and sort.
+    $module_data = system_rebuild_module_data();
+    // Create an associative array with weights as values.
+    $module_list = array_flip(array_values($module_list));
+
+    while (list($module) = each($module_list)) {
+      if (!isset($module_data[$module]) || !$module_data[$module]->status) {
+        // This module doesn't exist or is already disabled, skip it.
+        unset($module_list[$module]);
+        continue;
+      }
+      $module_list[$module] = $module_data[$module]->sort;
+
+      // Add dependent modules to the list, with a placeholder weight.
+      // The new modules will be processed as the while loop continues.
+      foreach ($module_data[$module]->required_by as $dependent => $dependent_data) {
+        if (!isset($module_list[$dependent]) && !strstr($module_data[$dependent]->filename, '.profile')) {
+          $module_list[$dependent] = 0;
+        }
+      }
+    }
+
+    // Sort the module list by pre-calculated weights.
+    asort($module_list);
+    $module_list = array_keys($module_list);
+  }
+
   $invoke_modules = array();
+
   foreach ($module_list as $module) {
     if (module_exists($module)) {
       // Check if node_access table needs rebuilding.
@@ -385,6 +464,7 @@ function module_disable($module_list) {
     module_invoke_all('modules_disabled', $invoke_modules);
     // Update the registry to remove the newly-disabled module.
     registry_update();
+    _system_update_bootstrap_status();
   }
 
   // If there remains no more node_access module, rebuilding will be
diff --git a/install.php b/install.php
index 3a086bd389059a628357f85ce545fbdff7a68073..0b9dddd87fde94e62d83336d8cb6e5f09e122db9 100644
--- a/install.php
+++ b/install.php
@@ -1505,7 +1505,7 @@ function _install_module_batch($module, $module_name, &$context) {
   // loaded by drupal_bootstrap in subsequent batch requests, and other
   // modules possibly depending on it can safely perform their installation
   // steps.
-  module_enable(array($module));
+  module_enable(array($module), FALSE);
   $context['results'][] = $module;
   $context['message'] = st('Installed %module module.', array('%module' => $module_name));
 }
@@ -1711,7 +1711,7 @@ function install_configure_form_submit($form, &$form_state) {
 
   // Enable update.module if this option was selected.
   if ($form_state['values']['update_status_module'][1]) {
-    drupal_install_modules(array('update'));
+    module_enable(array('update'), FALSE);
 
     // Add the site maintenance account's email address to the list of
     // addresses to be notified when updates are available, if selected.
diff --git a/modules/field/tests/field.test b/modules/field/tests/field.test
index b207bb55ef82ea0bc21a8bc81b0380726b4b5d6b..3052af9ade9b19c69ac4fc5127c4338812de2d6e 100644
--- a/modules/field/tests/field.test
+++ b/modules/field/tests/field.test
@@ -2253,7 +2253,7 @@ class FieldCrudTestCase extends FieldTestCase {
     $field = field_read_field($field_name);
     $this->assertTrue($field_definition <= $field, t('The field was properly read.'));
 
-    module_disable($modules);
+    module_disable($modules, FALSE);
 
     $fields = field_read_fields(array('field_name' => $field_name), array('include_inactive' => TRUE));
     $this->assertTrue(isset($fields[$field_name]) && $field_definition < $field, t('The field is properly read when explicitly fetching inactive fields.'));
@@ -2265,7 +2265,7 @@ class FieldCrudTestCase extends FieldTestCase {
       $this->assertTrue(empty($field), t('%modules disabled. The field is marked inactive.', array('%modules' => implode(', ', $modules))));
 
       $module = array_shift($modules);
-      module_enable(array($module));
+      module_enable(array($module), FALSE);
     }
 
     // Check that the field is active again after all modules have been
diff --git a/modules/simpletest/drupal_web_test_case.php b/modules/simpletest/drupal_web_test_case.php
index c5d2926e91cf8ed704e9aee1a58fb20bc4d481b2..9ba9355596166903110a2146bb8b3940c65667a2 100644
--- a/modules/simpletest/drupal_web_test_case.php
+++ b/modules/simpletest/drupal_web_test_case.php
@@ -1136,18 +1136,18 @@ protected function setUp() {
 
     $this->preloadRegistry();
 
-    // Include the default profile
+    // Include the default profile.
     variable_set('install_profile', 'standard');
     $profile_details = install_profile_info('standard', 'en');
 
     // Install the modules specified by the default profile.
-    drupal_install_modules($profile_details['dependencies'], TRUE);
+    module_enable($profile_details['dependencies'], FALSE, TRUE);
 
     drupal_static_reset('_node_types_build');
 
     if ($modules = func_get_args()) {
       // Install modules needed for this test.
-      drupal_install_modules($modules, TRUE);
+      module_enable($modules, TRUE, TRUE);
     }
 
     // Because the schema is static cached, we need to flush
@@ -1158,7 +1158,7 @@ protected function setUp() {
 
     // Run default profile tasks.
     $install_state = array();
-    drupal_install_modules(array('standard'), TRUE);
+    module_enable(array('standard'), FALSE, TRUE);
 
     // Rebuild caches.
     node_types_rebuild();
diff --git a/modules/simpletest/tests/module.test b/modules/simpletest/tests/module.test
index 939804953fd1be8957cbd0f1dc2f4303b879727f..242910c7f2932d3e0ff84b7989a7a995be416acb 100644
--- a/modules/simpletest/tests/module.test
+++ b/modules/simpletest/tests/module.test
@@ -37,7 +37,7 @@ class ModuleUnitTest extends DrupalWebTestCase {
     $this->assertModuleList($module_list, t('Standard profile'));
 
     // Try to install a new module.
-    drupal_install_modules(array('contact'));
+    module_enable(array('contact'));
     $module_list[] = 'contact';
     sort($module_list);
     $this->assertModuleList($module_list, t('After adding a module'));
@@ -101,25 +101,25 @@ class ModuleUnitTest extends DrupalWebTestCase {
   }
 
   /**
-   * Test drupal_install_modules() and dependency resolution.
+   * Test dependency resolution.
    */
-  function testDrupalInstallModules() {
-    drupal_install_modules(array('module_test'));
+  function testDependencyResolution() {
+    module_enable(array('module_test'), FALSE);
     $this->assertTrue(module_exists('module_test'), t('Test module is enabled.'));
 
     // First, create a fake missing dependency. Forum depends on poll, which
     // depends on a made-up module, foo. Nothing should be installed.
     variable_set('dependency_test', 'missing dependency');
-    $result = drupal_install_modules(array('forum'));
-    $this->assertFalse($result, t('drupal_install_modules() returns FALSE if dependencies are missing.'));
-    $this->assertFalse(module_exists('forum'), t('drupal_install_modules() aborts if dependencies are missing.'));
+    $result = module_enable(array('forum'));
+    $this->assertFalse($result, t('module_enable() returns FALSE if dependencies are missing.'));
+    $this->assertFalse(module_exists('forum'), t('module_enable() aborts if dependencies are missing.'));
 
-    // Now, fix the missing dependency. drupal_install_modules() should work.
+    // Now, fix the missing dependency. module_enable() should work.
     variable_set('dependency_test', 'dependency');
-    $result = drupal_install_modules(array('forum'));
-    $this->assertTrue($result, t('drupal_install_modules() returns the correct value.'));
+    $result = module_enable(array('forum'));
+    $this->assertTrue($result, t('module_enable() returns the correct value.'));
     // Verify that the fake dependency chain was installed.
-    $this->assertTrue(module_exists('poll') && module_exists('php'), t('Dependency chain was installed by drupal_install_modules().'));
+    $this->assertTrue(module_exists('poll') && module_exists('php'), t('Dependency chain was installed by module_enable().'));
     // Finally, verify that the original module was installed.
     $this->assertTrue(module_exists('forum'), t('Module installation with unlisted dependencies succeeded.'));
   }
diff --git a/modules/system/system.admin.inc b/modules/system/system.admin.inc
index c478e04653be2a3f00afa97e88c8e06e976e0563..fe6af7436267b2e84e81260d09263b40d592d38c 100644
--- a/modules/system/system.admin.inc
+++ b/modules/system/system.admin.inc
@@ -1203,7 +1203,7 @@ function system_modules_submit($form, &$form_state) {
       $sort[$module] = $files[$module]->sort;
     }
     array_multisort($sort, $modules_to_be_enabled);
-    module_enable($modules_to_be_enabled);
+    module_enable($modules_to_be_enabled, FALSE);
   }
   // Disable the modules that need disabling.
   if (!empty($disable_modules)) {
@@ -1225,7 +1225,7 @@ function system_modules_submit($form, &$form_state) {
       $sort[$module] = $files[$module]->sort;
     }
     array_multisort($sort, $new_modules);
-    drupal_install_modules($new_modules);
+    module_enable($new_modules, FALSE);
   }
 
   $current_module_list = module_list(TRUE);
diff --git a/modules/system/system.install b/modules/system/system.install
index c7ef22fd35dc5f61b21d814a831d9779c77cb0c4..b6c02d4e5985a12b1b4818d15986a29b3c2d88aa 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -2082,8 +2082,7 @@ function system_update_7018() {
  */
 function system_update_7020() {
   $module_list = array('field_sql_storage', 'field');
-  drupal_install_modules($module_list);
-  module_enable($module_list);
+  module_enable($module_list, FALSE);
 }
 
 /**
@@ -2305,8 +2304,7 @@ function system_update_7027() {
     ->condition('type', 'module')
     ->condition('name', $module_list)
     ->execute();
-  drupal_install_modules($module_list);
-  module_enable($module_list);
+  module_enable($module_list, FALSE);
 }
 
 /**
diff --git a/modules/system/system.module b/modules/system/system.module
index ef5b72af0c758174844e8421ea9ff759ce6b832b..58d135ffb390968efe9902ec9fb5076e317bddce 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -2203,7 +2203,18 @@ function system_rebuild_module_data() {
   ksort($modules);
   system_get_files_database($modules, 'module');
   system_update_files_database($modules, 'module');
-  // Refresh bootstrap status.
+  $modules = _module_build_dependencies($modules);
+  return $modules;
+}
+
+/**
+ * Refresh bootstrap column in the system table.
+ *
+ * This is called internally by module_enable/disable() to flag modules that
+ * implement hooks used during bootstrap, such as hook_boot(). These modules
+ * are loaded earlier to invoke the hooks.
+ */
+function _system_update_bootstrap_status() {
   $bootstrap_modules = array();
   foreach (bootstrap_hooks() as $hook) {
     foreach (module_implements($hook) as $module) {
@@ -2219,8 +2230,6 @@ function system_rebuild_module_data() {
     $query->condition('name', $bootstrap_modules, 'NOT IN');
   }
   $query->execute();
-  $modules = _module_build_dependencies($modules);
-  return $modules;
 }
 
 /**
diff --git a/modules/system/system.test b/modules/system/system.test
index 03545ce943cd6557ccf4b1a6575a165aa30e8e68..4e49ade61d3db9d34e1ecaf750f1d7d8e820758e 100644
--- a/modules/system/system.test
+++ b/modules/system/system.test
@@ -208,7 +208,7 @@ class ModuleDependencyTestCase extends ModuleTestCase {
     $this->assert(count($checkbox) == 1, t('Checkbox for the module is disabled.'));
 
     // Force enable the system_dependencies_test module.
-    module_enable(array('system_dependencies_test'));
+    module_enable(array('system_dependencies_test'), FALSE);
 
     // Verify that the module is forced to be disabled when submitting
     // the module page.