diff --git a/stdlib/cmake/modules/SwiftSource.cmake b/stdlib/cmake/modules/SwiftSource.cmake
index 95fe41128ee85..a6dd1e867a4b5 100644
--- a/stdlib/cmake/modules/SwiftSource.cmake
+++ b/stdlib/cmake/modules/SwiftSource.cmake
@@ -844,13 +844,17 @@ function(_compile_swift_files
     endif()
   endif()
 
-  # First generate the obj dirs
+  # First generate the obj dirs if not created before
   list(REMOVE_DUPLICATES dirs_to_create)
-  add_custom_command_target(
-      create_dirs_dependency_target
-      COMMAND "${CMAKE_COMMAND}" -E make_directory ${dirs_to_create}
-      OUTPUT ${dirs_to_create}
-      COMMENT "Generating dirs for ${first_output}")
+  list(REMOVE_ITEM dirs_to_create ${CREATED_OBJ_DIRS})
+  if(NOT dirs_to_create STREQUAL "")
+    add_custom_command_target(
+        create_dirs_dependency_target
+        COMMAND "${CMAKE_COMMAND}" -E make_directory ${dirs_to_create}
+        OUTPUT ${dirs_to_create}
+        COMMENT "Generating dirs for ${first_output}")
+    set(CREATED_OBJ_DIRS ${CREATED_OBJ_DIRS} ${dirs_to_create} CACHE INTERNAL "Already created obj directories") 
+  endif()
 
   # Then we can compile both the object files and the swiftmodule files
   # in parallel in this target for the object file, and ...
diff --git a/stdlib/public/CMakeLists.txt b/stdlib/public/CMakeLists.txt
index f2d759a190470..da063e5834712 100644
--- a/stdlib/public/CMakeLists.txt
+++ b/stdlib/public/CMakeLists.txt
@@ -136,12 +136,3 @@ endif()
 if(SWIFT_BUILD_SDK_OVERLAY OR SWIFT_BUILD_TEST_SUPPORT_MODULES)
   add_subdirectory(Platform)
 endif()
-
-if(SWIFT_BUILD_SDK_OVERLAY)
-  # On Apple platforms, we aren't building any overlays (other than Darwin in
-  # Platform above). Instead, we're picking them up from the SDK.
-
-  if(WINDOWS IN_LIST SWIFT_SDKS)
-    add_subdirectory(Windows)
-  endif()
-endif()
diff --git a/stdlib/public/Platform/CMakeLists.txt b/stdlib/public/Platform/CMakeLists.txt
index f958d4ce89954..b0672cd15e219 100644
--- a/stdlib/public/Platform/CMakeLists.txt
+++ b/stdlib/public/Platform/CMakeLists.txt
@@ -114,6 +114,16 @@ add_swift_target_library(swiftCRT ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVE
     TARGET_SDKS WINDOWS
     INSTALL_IN_COMPONENT sdk-overlay)
 
+add_swift_target_library(swiftWinSDK ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
+    WinSDK.swift
+
+    SWIFT_COMPILE_FLAGS
+      ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
+      ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+    LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
+    TARGET_SDKS WINDOWS
+    INSTALL_IN_COMPONENT sdk-overlay)
+
 set(glibc_modulemap_target_list)
 foreach(sdk ${SWIFT_SDKS})
   if(NOT "${sdk}" STREQUAL "LINUX" AND
diff --git a/stdlib/public/Windows/WinSDK.swift b/stdlib/public/Platform/WinSDK.swift
similarity index 100%
rename from stdlib/public/Windows/WinSDK.swift
rename to stdlib/public/Platform/WinSDK.swift
diff --git a/stdlib/public/Windows/CMakeLists.txt b/stdlib/public/Windows/CMakeLists.txt
deleted file mode 100644
index 65a2c8e9011a2..0000000000000
--- a/stdlib/public/Windows/CMakeLists.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-add_swift_target_library(swiftWinSDK ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
-    WinSDK.swift
-
-    SWIFT_COMPILE_FLAGS ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
-    LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
-    TARGET_SDKS WINDOWS
-    INSTALL_IN_COMPONENT sdk-overlay)
-