 diff --git a/Modules/Platform/UnixPaths.cmake b/Modules/Platform/UnixPaths.cmake
-index b9381c3d7d..cecc40a89e 100644
+index b9381c3d7d..5e944640b5 100644
 --- a/Modules/Platform/UnixPaths.cmake
 +++ b/Modules/Platform/UnixPaths.cmake
 @@ -26,9 +26,6 @@ get_filename_component(_CMAKE_INSTALL_DIR "${_CMAKE_INSTALL_DIR}" PATH)

   # CMake install location
   "${_CMAKE_INSTALL_DIR}"
   )
@@ -47,24 +44,19 @@ endif()
 
 # Non "standard" but common install prefixes
 list(APPEND CMAKE_SYSTEM_PREFIX_PATH

   )
 
 # List common include file locations not under the common prefixes.
+if(IS_DIRECTORY $ENV{NIX_CC})
+  file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc" _nix_cmake_libc)
+  file(STRINGS "$ENV{NIX_CC}/nix-support/orig-libc-dev" _nix_cmake_libc_dev)
+else()
+  set(_nix_cmake_libc @libc_lib@)
+  set(_nix_cmake_libc_dev @libc_dev@)
+endif()
+
 list(APPEND CMAKE_SYSTEM_INCLUDE_PATH
-  # X11
-  /usr/include/X11
+  "${_nix_cmake_libc_dev}/include"
   )
 
 list(APPEND CMAKE_SYSTEM_LIBRARY_PATH
-  # X11
-  /usr/lib/X11
+  "${_nix_cmake_libc}/lib"
   )
 
 list(APPEND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES
-  /lib /lib32 /lib64 /usr/lib /usr/lib32 /usr/lib64
+  "${_nix_cmake_libc}/lib"
   )
 
-if(CMAKE_SYSROOT_COMPILE)
-  set(_cmake_sysroot_compile "${CMAKE_SYSROOT_COMPILE}")
-else()
-  set(_cmake_sysroot_compile "${CMAKE_SYSROOT}")
-endif()
-
 # Default per-language values.  These may be later replaced after
 # parsing the implicit directory information from compiler output.
 set(_CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES_INIT
   ${CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES}
-  "${_cmake_sysroot_compile}/usr/include"
+  "${_nix_cmake_libc_dev}/include"
   )
 set(_CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES_INIT
   ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES}
-  "${_cmake_sysroot_compile}/usr/include"
+  "${_nix_cmake_libc_dev}/include"
   )
 set(_CMAKE_CUDA_IMPLICIT_INCLUDE_DIRECTORIES_INIT
   ${CMAKE_CUDA_IMPLICIT_INCLUDE_DIRECTORIES}
-  "${_cmake_sysroot_compile}/usr/include"
+  "${_nix_cmake_libc_dev}/include"
   )
 
-unset(_cmake_sysroot_compile)
+unset(_nix_cmake_libc)
+unset(_nix_cmake_libc_dev)
 
 # Reminder when adding new locations computed from environment variables
 # please make sure to keep Help/variable/CMAKE_SYSTEM_PREFIX_PATH.rst
diff --git a/Modules/Platform/WindowsPaths.cmake b/Modules/Platform/WindowsPaths.cmake
index b9e2f17979..ab517cd4a7 100644
--- a/Modules/Platform/WindowsPaths.cmake
