diff --git a/app/flatpak-builtins-build-init.c b/app/flatpak-builtins-build-init.c
index 5b2007c11..5973360b3 100644
--- a/app/flatpak-builtins-build-init.c
+++ b/app/flatpak-builtins-build-init.c
@@ -37,12 +37,18 @@ static char *opt_var;
 static char *opt_sdk_dir;
 static char **opt_sdk_extensions;
 static char **opt_tags;
+static char *opt_base;
+static char *opt_base_version;
+static char **opt_base_extensions;
 static gboolean opt_writable_sdk;
 static gboolean opt_update;
 
 static GOptionEntry options[] = {
   { "arch", 0, 0, G_OPTION_ARG_STRING, &opt_arch, N_("Arch to use"), N_("ARCH") },
   { "var", 'v', 0, G_OPTION_ARG_STRING, &opt_var, N_("Initialize var from named runtime"), N_("RUNTIME") },
+  { "base", 0, 0, G_OPTION_ARG_STRING, &opt_base, N_("Initialize apps from named app"), N_("APP") },
+  { "base-version", 0, 0, G_OPTION_ARG_STRING, &opt_base_version, N_("Specify version for --base"), N_("VERSION") },
+  { "base-extension", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_base_extensions, N_("Include this base extension"), N_("EXTENSION") },
   { "writable-sdk", 'w', 0, G_OPTION_ARG_NONE, &opt_writable_sdk, N_("Initialize /usr with a writable copy of the sdk"), NULL },
   { "tag", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_tags, N_("Add a tag"), N_("TAG") },
   { "sdk-extension", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_sdk_extensions, N_("Include this sdk extension in /usr"), N_("EXTENSION") },
@@ -229,6 +235,32 @@ flatpak_builtin_build_init (int argc, char **argv, GCancellable *cancellable, GE
   if (!g_file_make_directory (files_dir, cancellable, error))
     return FALSE;
 
+  if (opt_base)
+    {
+      const char *base_branch;
+      g_autofree char *base_ref = NULL;
+      g_autoptr(GError) my_error = NULL;
+      g_autoptr(GFile) base_deploy_files = NULL;
+      g_autoptr(FlatpakDeploy) base_deploy = NULL;
+
+      base_branch = opt_base_version ? opt_base_version : "master";
+      base_ref = flatpak_build_app_ref (opt_base, base_branch, opt_arch);
+      base_deploy = flatpak_find_deploy_for_ref (base_ref, cancellable, error);
+      if (base_deploy == NULL)
+        return FALSE;
+
+      base_deploy_files = flatpak_deploy_get_files (base_deploy);
+      if (!flatpak_cp_a (base_deploy_files, files_dir,
+                         FLATPAK_CP_FLAGS_MERGE | FLATPAK_CP_FLAGS_NO_CHOWN,
+                         cancellable, error))
+        return FALSE;
+
+
+      if (opt_base_extensions &&
+          !copy_extensions (base_deploy, base_branch, opt_base_extensions, files_dir, cancellable, error))
+        return FALSE;
+    }
+
   if (var_deploy_files)
     {
       if (!flatpak_cp_a (var_deploy_files, var_dir, FLATPAK_CP_FLAGS_NONE, cancellable, error))
diff --git a/doc/flatpak-build-init.xml b/doc/flatpak-build-init.xml
index 7ad9252e9..f013186f2 100644
--- a/doc/flatpak-build-init.xml
+++ b/doc/flatpak-build-init.xml
@@ -142,6 +142,31 @@
                 </para></listitem>
             </varlistentry>
 
+            <varlistentry>
+                <term><option>--base=APP</option></term>
+
+                <listitem><para>
+                    Initialize the application with files from another specified application.
+                </para></listitem>
+            </varlistentry>
+
+            <varlistentry>
+                <term><option>--base-version=VERSION</option></term>
+
+                <listitem><para>
+                    Specify the version to use for --base. If not specified, will default to
+                    "master".
+                </para></listitem>
+            </varlistentry>
+            <varlistentry>
+                <term><option>--base-extension=EXTENSION</option></term>
+
+                <listitem><para>
+                    When using --base, also install the specified extension from the app.
+                    This option can be used multiple times.
+                </para></listitem>
+            </varlistentry>
+
             <varlistentry>
                 <term><option>--verbose</option></term>