diff --git a/runtime/dart_isolate.cc b/runtime/dart_isolate.cc
index fd0c8332446d6..9f41ed8b2b379 100644
--- a/runtime/dart_isolate.cc
+++ b/runtime/dart_isolate.cc
@@ -184,11 +184,6 @@ bool DartIsolate::Initialize(Dart_Isolate dart_isolate) {
 
   SetMessageHandlingTaskRunner(GetTaskRunners().GetUITaskRunner());
 
-  if (tonic::LogIfError(
-          Dart_SetLibraryTagHandler(tonic::DartState::HandleLibraryTag))) {
-    return false;
-  }
-
   if (!UpdateThreadPoolNames()) {
     return false;
   }
@@ -623,10 +618,9 @@ Dart_Isolate DartIsolate::DartCreateAndStartServiceIsolate(
 
   tonic::DartState::Scope scope(service_isolate);
   if (!DartServiceIsolate::Startup(
-          settings.observatory_host,           // server IP address
-          settings.observatory_port,           // server observatory port
-          tonic::DartState::HandleLibraryTag,  // embedder library tag handler
-          false,  //  disable websocket origin check
+          settings.observatory_host,  // server IP address
+          settings.observatory_port,  // server observatory port
+          false,                      //  disable websocket origin check
           settings.disable_service_auth_codes,  // disable VM service auth codes
           error                                 // error (out)
           )) {
diff --git a/runtime/dart_service_isolate.cc b/runtime/dart_service_isolate.cc
index d13666be8fdf2..bc9da0910c0e3 100644
--- a/runtime/dart_service_isolate.cc
+++ b/runtime/dart_service_isolate.cc
@@ -30,7 +30,6 @@
 namespace flutter {
 namespace {
 
-static Dart_LibraryTagHandler g_embedder_tag_handler;
 static tonic::DartLibraryNatives* g_natives;
 static std::string g_observatory_uri;
 
@@ -127,17 +126,12 @@ void DartServiceIsolate::Shutdown(Dart_NativeArguments args) {
 
 bool DartServiceIsolate::Startup(std::string server_ip,
                                  intptr_t server_port,
-                                 Dart_LibraryTagHandler embedder_tag_handler,
                                  bool disable_origin_check,
                                  bool disable_service_auth_codes,
                                  char** error) {
   Dart_Isolate isolate = Dart_CurrentIsolate();
   FML_CHECK(isolate);
 
-  // Remember the embedder's library tag handler.
-  g_embedder_tag_handler = embedder_tag_handler;
-  FML_CHECK(g_embedder_tag_handler);
-
   // Setup native entries.
   if (!g_natives) {
     g_natives = new tonic::DartLibraryNatives();
diff --git a/runtime/dart_service_isolate.h b/runtime/dart_service_isolate.h
index 0adbabca9adb8..6f2f86878d397 100644
--- a/runtime/dart_service_isolate.h
+++ b/runtime/dart_service_isolate.h
@@ -23,7 +23,6 @@ class DartServiceIsolate {
 
   static bool Startup(std::string server_ip,
                       intptr_t server_port,
-                      Dart_LibraryTagHandler embedder_tag_handler,
                       bool disable_origin_check,
                       bool disable_service_auth_codes,
                       char** error);