diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 2517dd501efe8..3cb3250f67318 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -8591,13 +8591,7 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
 
   // Ignore C++11 attributes on declarator chunks: they appertain to the type
   // instead.
-  // FIXME: We currently check the attribute syntax directly instead of using
-  // isCXX11Attribute(), which currently erroneously classifies the C11
-  // `_Alignas` attribute as a C++11 attribute. `_Alignas` can appear on the
-  // `DeclSpec`, so we need to let it through here to make sure it is processed
-  // appropriately. Once the behavior of isCXX11Attribute() is fixed, we can
-  // go back to using that here.
-  if (AL.getSyntax() == ParsedAttr::AS_CXX11 && !Options.IncludeCXX11Attributes)
+  if (AL.isCXX11Attribute() && !Options.IncludeCXX11Attributes)
     return;
 
   // Unknown attributes are automatically warned on. Target-specific attributes