diff --git a/libc/src/__support/File/CMakeLists.txt b/libc/src/__support/File/CMakeLists.txt
--- a/libc/src/__support/File/CMakeLists.txt
+++ b/libc/src/__support/File/CMakeLists.txt
@@ -29,34 +29,29 @@
     libc.src.__support.threads.mutex
 )
 
-if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS}_file.cpp)
-  add_object_library(
-    platform_file
-    SRCS
-      ${LIBC_TARGET_OS}_file.cpp
-    DEPENDS
-      .file
-      libc.include.fcntl
-      libc.include.stdio
-      libc.include.sys_syscall
-      libc.src.__support.CPP.new
-      libc.src.__support.OSUtil.osutil
-      libc.src.errno.errno
-      libc.src.__support.error_or
-  )
+if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
+  return()
 endif()
 
-if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS}_dir.cpp)
-  add_object_library(
-    platform_dir
-    SRCS
-      ${LIBC_TARGET_OS}_dir.cpp
-    DEPENDS
-      .dir
-      libc.include.fcntl
-      libc.include.sys_syscall
-      libc.src.__support.OSUtil.osutil
-      libc.src.__support.error_or
-      libc.src.errno.errno
-  )
+add_subdirectory(${LIBC_TARGET_OS})
+set(target_file libc.src.__support.File.${LIBC_TARGET_OS}.${LIBC_TARGET_OS}_file)
+set(target_dir libc.src.__support.File.${LIBC_TARGET_OS}.${LIBC_TARGET_OS}_dir)
+if((NOT TARGET ${target_file}) OR (NOT TARGET ${target_dir}))
+  return()
 endif()
+
+add_object_library(
+  platform_file
+  ALIAS
+    ${target_file}
+  DEPENDS
+    ${target_file}
+)
+
+add_object_library(
+  platform_dir
+  ALIAS
+    ${target_dir}
+  DEPENDS
+    ${target_dir}
+)
diff --git a/libc/src/__support/File/linux/CMakeLists.txt b/libc/src/__support/File/linux/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/File/linux/CMakeLists.txt
@@ -0,0 +1,27 @@
+add_object_library(
+  linux_file
+  SRCS
+    file.cpp
+  DEPENDS
+    libc.include.fcntl
+    libc.include.stdio
+    libc.include.sys_syscall
+    libc.src.__support.CPP.new
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+    libc.src.__support.error_or
+    libc.src.__support.File.file
+)
+
+add_object_library(
+  linux_dir
+  SRCS
+    dir.cpp
+  DEPENDS
+    libc.include.fcntl
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.__support.error_or
+    libc.src.errno.errno
+    libc.src.__support.File.dir
+)
diff --git a/libc/src/__support/File/linux_dir.cpp b/libc/src/__support/File/linux/dir.cpp
rename from libc/src/__support/File/linux_dir.cpp
rename to libc/src/__support/File/linux/dir.cpp
--- a/libc/src/__support/File/linux_dir.cpp
+++ b/libc/src/__support/File/linux/dir.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "dir.h"
+#include "src/__support/File/dir.h"
 
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/error_or.h"
diff --git a/libc/src/__support/File/linux_file.cpp b/libc/src/__support/File/linux/file.cpp
rename from libc/src/__support/File/linux_file.cpp
rename to libc/src/__support/File/linux/file.cpp
--- a/libc/src/__support/File/linux_file.cpp
+++ b/libc/src/__support/File/linux/file.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "file.h"
+#include "src/__support/File/file.h"
 
 #include "src/__support/CPP/new.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.