diff --git a/legacy/elementary/src/lib/elm_theme.c b/legacy/elementary/src/lib/elm_theme.c
index 17e25aa716..3bb3858ea6 100644
--- a/legacy/elementary/src/lib/elm_theme.c
+++ b/legacy/elementary/src/lib/elm_theme.c
@@ -113,6 +113,31 @@ _elm_theme_file_item_del(Elm_Theme_Files *files, const char *str)
    eina_stringshare_del(str);
 }
 
+static void
+_elm_theme_file_mmap_del(Elm_Theme_Files *files, const Eina_File *file)
+{
+   Eina_List *l, *ll;
+   Eina_List *l2, *ll2;
+   Eina_File *f;
+
+   l2 = files->items;
+   EINA_LIST_FOREACH_SAFE(files->handles, l, ll, f)
+     {
+        ll2 = l2->next;
+
+        if (f == file)
+          {
+             eina_file_close(f);
+             eina_stringshare_del(eina_list_data_get(l2));
+
+             files->handles = eina_list_remove_list(files->handles, l);
+             files->items = eina_list_remove_list(files->items, l2);
+          }
+
+        l2 = ll2;
+     }
+}
+
 static void
 _elm_theme_file_clean(Elm_Theme_Files *files)
 {
@@ -533,6 +558,25 @@ elm_theme_overlay_del(Elm_Theme *th, const char *item)
    elm_theme_flush(th);
 }
 
+EAPI void
+elm_theme_overlay_mmap_add(Elm_Theme *th, const Eina_File *f)
+{
+   Eina_File *file = eina_file_dup(f);
+
+   if (!th) th = &(theme_default);
+   _elm_theme_item_finalize(&th->overlay, eina_file_filename_get(file), file);
+   elm_theme_flush(th);
+}
+
+EAPI void
+elm_theme_overlay_mmap_del(Elm_Theme *th, const Eina_File *f)
+{
+   if (!f) return ;
+   if (!th) th = &(theme_default);
+   _elm_theme_file_mmap_del(&th->overlay, f);
+   elm_theme_flush(th);
+}
+
 EAPI const Eina_List *
 elm_theme_overlay_list_get(const Elm_Theme *th)
 {
@@ -558,6 +602,26 @@ elm_theme_extension_del(Elm_Theme *th, const char *item)
    elm_theme_flush(th);
 }
 
+EAPI void
+elm_theme_extension_mmap_add(Elm_Theme *th, const Eina_File *f)
+{
+   Eina_File *file = eina_file_dup(f);
+
+   if (!f) return ;
+   if (!th) th = &(theme_default);
+   _elm_theme_item_finalize(&th->overlay, eina_file_filename_get(file), file);
+   elm_theme_flush(th);
+}
+
+EAPI void
+elm_theme_extension_mmap_del(Elm_Theme *th, const Eina_File *f)
+{
+   if (!f) return ;
+   if (!th) th = &(theme_default);
+   _elm_theme_file_mmap_del(&th->extension, f);
+   elm_theme_flush(th);
+}
+
 EAPI const Eina_List *
 elm_theme_extension_list_get(const Elm_Theme *th)
 {
diff --git a/legacy/elementary/src/lib/elm_theme.h b/legacy/elementary/src/lib/elm_theme.h
index b4467d91d3..5aa3b31db3 100644
--- a/legacy/elementary/src/lib/elm_theme.h
+++ b/legacy/elementary/src/lib/elm_theme.h
@@ -179,6 +179,7 @@ EAPI Elm_Theme       *elm_theme_default_get(void);
  * of trouble.
  *
  * @see elm_theme_extension_add()
+ * @see elm_theme_overlay_mmap_add()
  *
  * @ingroup Theme
  */
@@ -196,6 +197,40 @@ EAPI void             elm_theme_overlay_add(Elm_Theme *th, const char *item);
  */
 EAPI void             elm_theme_overlay_del(Elm_Theme *th, const char *item);
 
+/**
+ * Prepends a theme overlay to the list of overlays
+ *
+ * @param th The theme to add to, or if NULL, the default theme
+ * @param f The Edje file handle to be used
+ *
+ * Use this if your application needs to provide some custom overlay theme
+ * (An Edje file that replaces some default styles of widgets) where adding
+ * new styles, or changing system theme configuration is not possible. Do
+ * NOT use this instead of a proper system theme configuration. Use proper
+ * configuration files, profiles, environment variables etc. to set a theme
+ * so that the theme can be altered by simple configuration by a user. Using
+ * this call to achieve that effect is abusing the API and will create lots
+ * of trouble.
+ *
+ * @see elm_theme_extension_add()
+ * @see elm_theme_overlay_add()
+ *
+ * @ingroup Theme
+ */
+EAPI void             elm_theme_overlay_mmap_add(Elm_Theme *th, const Eina_File *f);
+
+/**
+ * Delete a theme overlay from the list of overlays
+ *
+ * @param th The theme to delete from, or if NULL, the default theme
+ * @param f The file handle of the theme overlay
+ *
+ * @see elm_theme_overlay_mmap_add()
+ *
+ * @ingroup Theme
+ */
+EAPI void             elm_theme_overlay_mmap_del(Elm_Theme *th, const Eina_File *f);
+
 /**
  * Get the list of registered overlays for the given theme
  *
@@ -243,6 +278,41 @@ EAPI void             elm_theme_extension_add(Elm_Theme *th, const char *item);
  */
 EAPI void             elm_theme_extension_del(Elm_Theme *th, const char *item);
 
+/**
+ * Appends a theme extension to the list of extensions.
+ *
+ * @param th The theme to add to, or if NULL, the default theme
+ * @param f The Edje file handle to be used
+ *
+ * This is intended when an application needs more styles of widgets or new
+ * widget themes that the default does not provide (or may not provide). The
+ * application has "extended" usage by coming up with new custom style names
+ * for widgets for specific uses, but as these are not "standard", they are
+ * not guaranteed to be provided by a default theme. This means the
+ * application is required to provide these extra elements itself in specific
+ * Edje files. This call adds one of those Edje files to the theme search
+ * path to be search after the default theme. The use of this call is
+ * encouraged when default styles do not meet the needs of the application.
+ * Use this call instead of elm_theme_overlay_add() for almost all cases.
+ *
+ * @see elm_object_style_set()
+ *
+ * @ingroup Theme
+ */
+EAPI void             elm_theme_extension_mmap_add(Elm_Theme *th, const Eina_File *f);
+
+/**
+ * Deletes a theme extension from the list of extensions.
+ *
+ * @param th The theme to delete from, or if NULL, the default theme
+ * @param f The file handle of the theme extension
+ *
+ * @see elm_theme_extension_add()
+ *
+ * @ingroup Theme
+ */
+EAPI void             elm_theme_extension_mmap_del(Elm_Theme *th, const Eina_File *f);
+
 /**
  * Get the list of registered extensions for the given theme
  *