diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index a714419..a43b2d1 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -1022,6 +1022,14 @@ function comment_build_content(Comment $comment, $node, $view_mode = 'full', $la
   // Remove previously built content, if exists.
   $comment->content = array();
 
+  // Allow modules to change the view mode.
+  $context = array(
+    'entity_type' => 'comment',
+    'entity' => $comment,
+    'langcode' => $langcode,
+  );
+  drupal_alter('entity_view_mode', $view_mode, $context);
+
   // Build fields content.
   field_attach_prepare_view('comment', array($comment->cid => $comment), $view_mode, $langcode);
   entity_prepare_view('comment', array($comment->cid => $comment), $langcode);
diff --git a/core/modules/entity/entity.api.php b/core/modules/entity/entity.api.php
index e983778..f7fe4a9 100644
--- a/core/modules/entity/entity.api.php
+++ b/core/modules/entity/entity.api.php
@@ -444,3 +444,15 @@ function hook_entity_prepare_view($entities, $type) {
     }
   }
 }
+
+/**
+ * Change the view mode of an entity that is being displayed.
+ *
+ * @param string $view_mode
+ *   The view_mode that is to be used to display the entity.
+ * @param array $context
+ *   An array with the keys entity_type, entity and langcode.
+ */
+function hook_entity_view_mode_alter(&$view_mode, array $context) {
+
+}
\ No newline at end of file
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index a59a5c7..9da9f5d 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -1406,6 +1406,14 @@ function node_build_content($node, $view_mode = 'full', $langcode = NULL) {
   // Remove previously built content, if exists.
   $node->content = array();
 
+  // Allow modules to change the view mode.
+  $context = array(
+    'entity_type' => 'node',
+    'entity' => $node,
+    'langcode' => $langcode,
+  );
+  drupal_alter('entity_view_mode', $view_mode, $context);
+
   // The 'view' hook can be implemented to overwrite the default function
   // to display nodes.
   if (node_hook($node, 'view')) {
diff --git a/core/modules/taxonomy/taxonomy.module b/core/modules/taxonomy/taxonomy.module
index e82edfc..a7d5974 100644
--- a/core/modules/taxonomy/taxonomy.module
+++ b/core/modules/taxonomy/taxonomy.module
@@ -583,6 +583,14 @@ function taxonomy_term_view(TaxonomyTerm $term, $view_mode = 'full', $langcode =
     $langcode = $GLOBALS['language_content']->langcode;
   }
 
+  // Allow modules to change the view mode.
+  $context = array(
+    'entity_type' => 'taxonomy_term',
+    'entity' => $term,
+    'langcode' => $langcode,
+  );
+  drupal_alter('entity_view_mode', $view_mode, $context);
+
   field_attach_prepare_view('taxonomy_term', array($term->tid => $term), $view_mode, $langcode);
   entity_prepare_view('taxonomy_term', array($term->tid => $term), $langcode);
 
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 3b1d9cb..db50054 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -2560,6 +2560,14 @@ function user_build_content($account, $view_mode = 'full', $langcode = NULL) {
   // Remove previously built content, if exists.
   $account->content = array();
 
+  // Allow modules to change the view mode.
+  $context = array(
+    'entity_type' => 'user',
+    'entity' => $account,
+    'langcode' => $langcode,
+  );
+  drupal_alter('entity_view_mode', $view_mode, $context);
+
   // Build fields content.
   field_attach_prepare_view('user', array($account->uid => $account), $view_mode, $langcode);
   entity_prepare_view('user', array($account->uid => $account), $langcode);