diff --git a/libcxx/cmake/Modules/HandleLibCXXABI.cmake b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
--- a/libcxx/cmake/Modules/HandleLibCXXABI.cmake
+++ b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
@@ -10,14 +10,6 @@
 #   abidefines: A list of defines needed to compile libc++ with the ABI library
 #   abishared : The shared ABI library to link against.
 #   abistatic : The static ABI library to link against.
-#   abifiles  : A list of files (which may be relative paths) to copy into the
-#               libc++ build tree for the build.  These files will be copied
-#               twice: once into include/, so the libc++ build itself can find
-#               them, and once into include/c++/v1, so that a clang built into
-#               the same build area will find them.  These files will also be
-#               installed alongside the libc++ headers.
-#   abidirs   : A list of relative paths to create under an include directory
-#               in the libc++ build directory.
 #
 
 macro(setup_abi_lib abidefines abishared abistatic abifiles abidirs)
@@ -32,54 +24,6 @@
     )
   set(LIBCXX_CXX_SHARED_ABI_LIBRARY ${abishared})
   set(LIBCXX_CXX_STATIC_ABI_LIBRARY ${abistatic})
-  set(LIBCXX_ABILIB_FILES ${abifiles})
-
-  foreach(fpath ${LIBCXX_ABILIB_FILES})
-    set(found FALSE)
-    foreach(incpath ${LIBCXX_CXX_ABI_INCLUDE_PATHS})
-      message(STATUS "Looking for ${fpath} in ${incpath}")
-      if (EXISTS "${incpath}/${fpath}")
-        set(found TRUE)
-        message(STATUS "Looking for ${fpath} in ${incpath} - found")
-        get_filename_component(dstdir ${fpath} PATH)
-        get_filename_component(ifile ${fpath} NAME)
-        set(src ${incpath}/${fpath})
-
-        set(dst ${LIBCXX_BINARY_INCLUDE_DIR}/${dstdir}/${ifile})
-        add_custom_command(OUTPUT ${dst}
-            DEPENDS ${src}
-            COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dst}
-            COMMENT "Copying C++ ABI header ${fpath}...")
-        list(APPEND abilib_headers "${dst}")
-
-        # TODO: libc++ shouldn't be responsible for copying the libc++abi
-        # headers into the right location.
-        set(dst "${LIBCXX_GENERATED_INCLUDE_DIR}/${dstdir}/${fpath}")
-        add_custom_command(OUTPUT ${dst}
-            DEPENDS ${src}
-            COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dst}
-            COMMENT "Copying C++ ABI header ${fpath}...")
-        list(APPEND abilib_headers "${dst}")
-
-        if (LIBCXX_INSTALL_HEADERS)
-          install(FILES "${LIBCXX_BINARY_INCLUDE_DIR}/${fpath}"
-            DESTINATION include/c++/v1/${dstdir}
-            COMPONENT cxx-headers
-            PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
-            )
-        endif()
-      else()
-        message(STATUS "Looking for ${fpath} in ${incpath} - not found")
-      endif()
-    endforeach()
-    if (NOT found)
-      message(WARNING "Failed to find ${fpath} in ${LIBCXX_CXX_ABI_INCLUDE_PATHS}")
-    endif()
-  endforeach()
-
-  include_directories("${LIBCXX_BINARY_INCLUDE_DIR}")
-  add_custom_target(cxx_abi_headers ALL DEPENDS ${abilib_headers})
-  set(LIBCXX_CXX_ABI_HEADER_TARGET "cxx_abi_headers")
 endmacro()
 
 
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -225,7 +225,7 @@
 add_custom_target(generate-cxx-headers ALL DEPENDS ${_all_includes})
 
 add_library(cxx-headers INTERFACE)
-add_dependencies(cxx-headers generate-cxx-headers ${LIBCXX_CXX_ABI_HEADER_TARGET})
+add_dependencies(cxx-headers generate-cxx-headers)
 # TODO: Use target_include_directories once we figure out why that breaks the runtimes build
 if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
   target_compile_options(cxx-headers INTERFACE /I "${LIBCXX_GENERATED_INCLUDE_DIR}")
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -172,10 +172,6 @@
 endif()
 
 function(cxx_set_common_defines name)
-  if(LIBCXX_CXX_ABI_HEADER_TARGET)
-    add_dependencies(${name} ${LIBCXX_CXX_ABI_HEADER_TARGET})
-  endif()
-
   if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
     target_link_libraries(${name} PUBLIC pstl::ParallelSTL)
   endif()
diff --git a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
--- a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -268,17 +268,6 @@
       "wctype.h",
     ]
     deps = [ ":write_config_site" ]
-    if (target_os != "mac" && target_os != "win") {
-      # libcxx/cmake/Modules/HandleLibCXXABI.cmake sets
-      # LIBCXX_CXX_ABI_HEADER_TARGET if the libcxx abi library either of
-      # "libstdc++", "libsupc++", "libcxxabi", "libcxxrt", but not if it's "none",
-      # "default", or "vcruntime". So on Windows, these don't get copied due to
-      # LIBCXX_CXX_ABI_HEADER_TARGET not being set.
-      # On macOS, libcxx/CMakeLists.txt sets LIBCXX_CXX_ABI_SYSTEM to 1, which
-      # causes an empty header list to be passed to setup_abi_lib, so these
-      # don't get copied on macOS due to that.
-      deps += [ "//libcxxabi/include" ]
-    }
     outputs = [ "$root_build_dir/include/c++/v1/{{source_target_relative}}" ]
   }
 }