diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index a1b9954..e168d0d 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -1085,6 +1085,7 @@
       .Case("cxx_exceptions", LangOpts.CXXExceptions)
       .Case("cxx_rtti", LangOpts.RTTI && LangOpts.RTTIData)
       .Case("enumerator_attributes", true)
+      .Case("generalized_swift_name", true)
       .Case("nullability", true)
       .Case("memory_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Memory))
       .Case("thread_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Thread))