diff --git a/CMakeLists.txt b/CMakeLists.txt
index ac3a7515957c4..be5e1cf2333be 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1269,10 +1269,10 @@ else()
 
   if(SWIFT_BUILD_STDLIB_EXTRA_TOOLCHAIN_CONTENT)
     add_subdirectory(stdlib/toolchain)
-  endif()
 
-  if(SWIFT_BUILD_STDLIB_CXX_MODULE)
-    add_subdirectory(stdlib/public/Cxx)
+    if(SWIFT_BUILD_STDLIB_CXX_MODULE)
+      add_subdirectory(stdlib/public/Cxx)
+    endif()
   endif()
 
   if (BUILD_SWIFT_CONCURRENCY_BACK_DEPLOYMENT_LIBRARIES)