diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2394,9 +2394,9 @@
     DiagMask = DiagnosticLevelMask::All;
   Opts.setVerifyIgnoreUnexpected(DiagMask);
   if (Opts.TabStop == 0 || Opts.TabStop > DiagnosticOptions::MaxTabStop) {
-    Opts.TabStop = DiagnosticOptions::DefaultTabStop;
     Diags->Report(diag::warn_ignoring_ftabstop_value)
         << Opts.TabStop << DiagnosticOptions::DefaultTabStop;
+    Opts.TabStop = DiagnosticOptions::DefaultTabStop;
   }
 
   addDiagnosticArgs(Args, OPT_W_Group, OPT_W_value_Group, Opts.Warnings);