diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -19,16 +19,26 @@
 
 set(LIBC_ENABLE_USE_BY_CLANG OFF CACHE BOOL "Whether or not to place libc in a build directory findable by a just built clang")
 
-if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND LIBC_ENABLE_USE_BY_CLANG)
+if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
+  set(LIBC_INCLUDE_DIR ${LLVM_BINARY_DIR}/include/gpu-none-llvm)
+  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR}/gpu-none-llvm)
+  set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/gnu-none-llvm)
+elseif(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND LIBC_ENABLE_USE_BY_CLANG)
+  set(LIBC_INCLUDE_DIR ${LLVM_BINARY_DIR}/include/${LLVM_DEFAULT_TARGET_TRIPLE})
+  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
   set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
 else()
   if(NOT LIBC_ENABLE_USE_BY_CLANG)
-    set(LIBC_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+    set(LIBC_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
+    set(LIBC_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/lib)
   elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
+    set(LIBC_INCLUDE_DIR ${LLVM_BINARY_DIR}/include)
     set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
   else()
+    set(LIBC_INCLUDE_DIR ${CMAKE_BINARY_DIR}/include)
     set(LIBC_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
   endif()
+  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR})
 endif()
 
 if(LLVM_LIBC_FULL_BUILD OR LIBC_GPU_BUILD OR LIBC_GPU_ARCHITECTURES)
diff --git a/libc/cmake/modules/LLVMLibCHeaderRules.cmake b/libc/cmake/modules/LLVMLibCHeaderRules.cmake
--- a/libc/cmake/modules/LLVMLibCHeaderRules.cmake
+++ b/libc/cmake/modules/LLVMLibCHeaderRules.cmake
@@ -18,12 +18,14 @@
     message(FATAL_ERROR "'add_header' rules requires the HDR argument specifying a headef file.")
   endif()
 
-  set(dest_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_HEADER_HDR})
+  set(absolute_path ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_HEADER_HDR})
+  file(RELATIVE_PATH relative_path ${LIBC_INCLUDE_SOURCE_DIR} ${absolute_path})
+  set(dest_file ${LIBC_INCLUDE_DIR}/${relative_path})
   set(src_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_HEADER_HDR})
 
   add_custom_command(
     OUTPUT ${dest_file}
-    COMMAND cp ${src_file} ${dest_file}
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src_file} ${dest_file}
     DEPENDS ${src_file}
   )
 
@@ -86,7 +88,9 @@
     message(FATAL_ERROR "`add_gen_hdr` rule requires GEN_HDR to be specified.")
   endif()
 
-  set(out_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_GEN_HDR_GEN_HDR})
+  set(absolute_path ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR_GEN_HDR})
+  file(RELATIVE_PATH relative_path ${LIBC_INCLUDE_SOURCE_DIR} ${absolute_path})
+  set(out_file ${LIBC_INCLUDE_DIR}/${relative_path})
   set(in_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR_DEF_FILE})
 
   set(fq_data_files "")
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -1,4 +1,6 @@
+set(LIBC_INCLUDE_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(LIBC_INCLUDE_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+
 include(LLVMLibCHeaderRules)
 
 add_subdirectory(llvm-libc-macros)
@@ -522,8 +524,10 @@
 endfunction(get_all_install_header_targets)
 
 get_all_install_header_targets(all_install_header_targets ${TARGET_PUBLIC_HEADERS})
-add_custom_target(libc-headers)
+add_library(libc-headers INTERFACE)
 add_dependencies(libc-headers ${all_install_header_targets})
+target_include_directories(libc-headers SYSTEM INTERFACE ${LIBC_INCLUDE_DIR})
+
 foreach(target IN LISTS all_install_header_targets)
   get_target_property(header_file ${target} HEADER_FILE_PATH)
   if(NOT header_file)
@@ -532,12 +536,7 @@
   endif()
   file(RELATIVE_PATH relative_path ${LIBC_INCLUDE_BINARY_DIR} ${header_file})
   get_filename_component(nested_dir ${relative_path} DIRECTORY)
-  # The GPU headers are installed to 'gpu-none-llvm/' to prevent shadowing the
-  # system headers.
-  if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
-    set(nested_dir gpu-none-llvm/${nested_dir})
-  endif()
   install(FILES ${header_file}
-          DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/${nested_dir}
+          DESTINATION ${LIBC_INSTALL_INCLUDE_DIR}/${nested_dir}
           COMPONENT libc-headers)
 endforeach()