diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 2fd2ae434d7c5..254b13be005bb 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -115,6 +115,8 @@ def err_fe_unable_to_load_plugin : Error<
     "unable to load plugin '%0': '%1'">;
 def err_fe_unable_to_create_target : Error<
     "unable to create target: '%0'">;
+def err_fe_unable_to_create_subtarget : Error<
+    "unable to create subtarget: '%0'%select{ with features '%2'|}1">;
 def err_fe_unable_to_interface_with_target : Error<
     "unable to interface with target machine">;
 def err_fe_unable_to_open_output : Error<
diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index 5c30de33c7b46..dc0f74957774a 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -480,7 +480,10 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
 
   std::unique_ptr<MCSubtargetInfo> STI(
       TheTarget->createMCSubtargetInfo(Opts.Triple, Opts.CPU, FS));
-  assert(STI && "Unable to create subtarget info!");
+  if (!STI) {
+    return Diags.Report(diag::err_fe_unable_to_create_subtarget)
+           << Opts.CPU << FS.empty() << FS;
+  }
 
   MCContext Ctx(Triple(Opts.Triple), MAI.get(), MRI.get(), STI.get(), &SrcMgr,
                 &MCOptions);