diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -429,6 +429,7 @@
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
 else()
   set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
+  set(LIBCXX_HEADER_DIR  ${CMAKE_BINARY_DIR})
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
 endif()
 
@@ -874,22 +875,11 @@
   config_define(ON _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
 endif()
 
-# We generate a __config_site header (see libcxx/include/CMakeLists.txt) and
-# we make sure to include it when building the library.
-function(cxx_add_config_site target)
-  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
-    target_compile_options(${target} PUBLIC /FI "${LIBCXX_BINARY_DIR}/__config_site")
-  else()
-    target_compile_options(${target} PUBLIC -include "${LIBCXX_BINARY_DIR}/__config_site")
-  endif()
-endfunction()
-
 # Setup all common build flags =================================================
 function(cxx_add_common_build_flags target)
   cxx_add_basic_build_flags(${target})
   cxx_add_warning_flags(${target})
   cxx_add_windows_flags(${target})
-  cxx_add_config_site(${target})
   cxx_add_exception_flags(${target})
   cxx_add_rtti_flags(${target})
   cxx_add_module_flags(${target})
@@ -899,7 +889,6 @@
 #===============================================================================
 # Setup Source Code And Tests
 #===============================================================================
-include_directories(include)
 add_subdirectory(include)
 add_subdirectory(src)
 
diff --git a/libcxx/cmake/Modules/DefineLinkerScript.cmake b/libcxx/cmake/Modules/DefineLinkerScript.cmake
--- a/libcxx/cmake/Modules/DefineLinkerScript.cmake
+++ b/libcxx/cmake/Modules/DefineLinkerScript.cmake
@@ -31,6 +31,9 @@
   set(link_libraries)
   if (interface_libs)
     foreach(lib IN LISTS interface_libs)
+      if ("${lib}" STREQUAL "cxx-headers")
+        continue()
+      endif()
       if (TARGET "${lib}" OR
           (${lib} MATCHES "cxxabi(_static|_shared)?" AND HAVE_LIBCXXABI) OR
           (${lib} MATCHES "unwind(_static|_shared)?" AND HAVE_LIBUNWIND))
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -201,7 +201,6 @@
 # Add a target that executes the generation commands.
 add_custom_target(cxx-generated-config ALL
   DEPENDS ${LIBCXX_BINARY_DIR}/__generated_config)
-set(generated_config_deps cxx-generated-config)
 
 # In some build configurations (like bootstrapping clang), we need to be able to
 # install the libcxx headers before the CMake configuration for libcxx runs. Making
@@ -229,16 +228,30 @@
   set(src ${LIBCXX_BINARY_DIR}/__generated_config)
   set(dst ${output_dir}/__config)
   add_custom_command(OUTPUT ${dst}
-      DEPENDS ${src} ${generated_config_deps}
+      DEPENDS ${src} cxx-generated-config
       COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dst}
       COMMENT "Copying CXX __config")
   list(APPEND out_files ${dst})
+  add_custom_target(generate-cxx-headers DEPENDS ${out_files})
 
-  add_custom_target(${CXX_HEADER_TARGET} ALL DEPENDS ${out_files} ${LIBCXX_CXX_ABI_HEADER_TARGET})
+  add_library(${CXX_HEADER_TARGET} INTERFACE)
+  add_dependencies(${CXX_HEADER_TARGET} generate-cxx-headers ${LIBCXX_CXX_ABI_HEADER_TARGET})
+  # TODO: Use target_include_directories once we figure out why that breaks the runtimes build
+  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
+    target_compile_options(${CXX_HEADER_TARGET} INTERFACE /I "${output_dir}")
+  else()
+    target_compile_options(${CXX_HEADER_TARGET} INTERFACE -I "${output_dir}")
+  endif()
+
+  # Make sure the generated __config_site header is included when we build the library.
+  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
+    target_compile_options(${CXX_HEADER_TARGET} INTERFACE /FI "${LIBCXX_BINARY_DIR}/__config_site")
+  else()
+    target_compile_options(${CXX_HEADER_TARGET} INTERFACE -include "${LIBCXX_BINARY_DIR}/__config_site")
+  endif()
 else()
-  add_custom_target(${CXX_HEADER_TARGET})
+  add_library(${CXX_HEADER_TARGET} INTERFACE)
 endif()
-set_target_properties(${CXX_HEADER_TARGET} PROPERTIES FOLDER "Misc")
 
 if (LIBCXX_INSTALL_HEADERS)
   foreach(file ${files})
@@ -259,7 +272,7 @@
 
   if (NOT CMAKE_CONFIGURATION_TYPES)
     add_custom_target(install-${CXX_HEADER_TARGET}
-                      DEPENDS ${CXX_HEADER_TARGET} ${generated_config_deps}
+                      DEPENDS ${CXX_HEADER_TARGET} cxx-generated-config
                       COMMAND "${CMAKE_COMMAND}"
                               -DCMAKE_INSTALL_COMPONENT=${CXX_HEADER_TARGET}
                               -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -163,7 +163,8 @@
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(cxx_shared)
   endif()
-  target_link_libraries(cxx_shared PRIVATE ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_shared PUBLIC cxx-headers
+                                   PRIVATE ${LIBCXX_LIBRARIES})
   set_target_properties(cxx_shared
     PROPERTIES
       COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
@@ -244,7 +245,8 @@
 # Build the static library.
 if (LIBCXX_ENABLE_STATIC)
   add_library(cxx_static STATIC ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
-  target_link_libraries(cxx_static PRIVATE ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_static PUBLIC cxx-headers
+                                   PRIVATE ${LIBCXX_LIBRARIES})
   set(CMAKE_STATIC_LIBRARY_PREFIX "lib")
   set_target_properties(cxx_static
     PROPERTIES
@@ -298,7 +300,7 @@
 endif()
 
 # Add a meta-target for both libraries.
-add_custom_target(cxx DEPENDS cxx-headers ${LIBCXX_BUILD_TARGETS})
+add_custom_target(cxx DEPENDS ${LIBCXX_BUILD_TARGETS})
 
 if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
   set(LIBCXX_EXPERIMENTAL_SOURCES