diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -156,9 +156,23 @@
   message(FATAL_ERROR "libc++abi must be built as either a shared or static library.")
 endif()
 
-set(LIBCXXABI_LIBCXX_INCLUDES "${LIBCXXABI_LIBCXX_PATH}/include" CACHE PATH
-    "Specify path to libc++ includes.")
-message(STATUS "Libc++abi will be using libc++ includes from ${LIBCXXABI_LIBCXX_INCLUDES}")
+# TODO: This is a workaround for the fact that Standalone builds can't use
+# targets from the other runtimes (so the cxx-headers target doesn't exist).
+set(LIBCXXABI_LIBCXX_INCLUDES "" CACHE PATH
+    "Specify path to the installed libc++ includes. This is only relevant for Standalone builds, where the location of the headers can't be determined automatically.")
+if (LIBCXXABI_STANDALONE_BUILD)
+  if (NOT IS_DIRECTORY ${LIBCXXABI_LIBCXX_INCLUDES})
+    message(FATAL_ERROR
+      "LIBCXXABI_LIBCXX_INCLUDES=${LIBCXXABI_LIBCXX_INCLUDES} is not a valid directory. "
+      "Please provide the path to where the libc++ headers have been installed.")
+  endif()
+  add_library(cxx-headers INTERFACE)
+  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
+    target_compile_options(cxx-headers INTERFACE /I "${LIBCXXABI_LIBCXX_INCLUDES}")
+  else()
+    target_compile_options(cxx-headers INTERFACE -I "${LIBCXXABI_LIBCXX_INCLUDES}")
+  endif()
+endif()
 
 option(LIBCXXABI_HERMETIC_STATIC_LIBRARY
   "Do not export any symbols from the static library." OFF)
@@ -375,11 +389,6 @@
                         " be set to ON when LIBCXXABI_ENABLE_THREADS"
                         " is also set to ON.")
   endif()
-  if (LIBCXXABI_HAS_WIN32_THREAD_API)
-    message(FATAL_ERROR "LIBCXXABI_HAS_WIN32_THREAD_API can only"
-                        " be set to ON when LIBCXXABI_ENABLE_THREADS"
-                        " is also set to ON.")
-  endif()
   if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
     message(FATAL_ERROR "LIBCXXABI_HAS_EXTERNAL_THREAD_API can only"
                         " be set to ON when LIBCXXABI_ENABLE_THREADS"
@@ -400,11 +409,6 @@
                         " and LIBCXXABI_HAS_PTHREAD_API cannot be both"
                         " set to ON at the same time.")
   endif()
-  if (LIBCXXABI_HAS_WIN32_THREAD_API)
-    message(FATAL_ERROR "The options LIBCXXABI_HAS_EXTERNAL_THREAD_API"
-                        " and LIBCXXABI_HAS_WIN32_THREAD_API cannot be both"
-                        " set to ON at the same time.")
-  endif()
   if (LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY)
     message(FATAL_ERROR "The options LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY"
                         " and LIBCXXABI_HAS_EXTERNAL_THREAD_API cannot be both"
@@ -412,14 +416,6 @@
   endif()
 endif()
 
-if (LIBCXXABI_HAS_PTHREAD_API)
-  if (LIBCXXABI_HAS_WIN32_THREAD_API)
-    message(FATAL_ERROR "The options LIBCXXABI_HAS_PTHREAD_API"
-            "and LIBCXXABI_HAS_WIN32_THREAD_API cannot be both"
-            "set to ON at the same time.")
-  endif()
-endif()
-
 if (LLVM_ENABLE_MODULES)
   # Ignore that the rest of the modules flags are now unused.
   add_compile_flags_if_supported(-Wno-unused-command-line-argument)
@@ -447,10 +443,6 @@
   add_definitions(-D_LIBCPP_HAS_THREAD_API_PTHREAD)
 endif()
 
-if (LIBCXXABI_HAS_WIN32_THREAD_API)
-  add_definitions(-D_LIBCPP_HAS_THREAD_API_WIN32)
-endif()
-
 if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
   add_definitions(-D_LIBCPP_HAS_THREAD_API_EXTERNAL)
 endif()
diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -177,7 +177,7 @@
 # Build the shared library.
 if (LIBCXXABI_ENABLE_SHARED)
   add_library(cxxabi_shared SHARED ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
-  target_link_libraries(cxxabi_shared PRIVATE ${LIBCXXABI_SHARED_LIBRARIES} ${LIBCXXABI_LIBRARIES})
+  target_link_libraries(cxxabi_shared PRIVATE cxx-headers ${LIBCXXABI_SHARED_LIBRARIES} ${LIBCXXABI_LIBRARIES})
   if (TARGET pstl::ParallelSTL)
     target_link_libraries(cxxabi_shared PUBLIC pstl::ParallelSTL)
   endif()
@@ -244,7 +244,7 @@
 # Build the static library.
 if (LIBCXXABI_ENABLE_STATIC)
   add_library(cxxabi_static STATIC ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
-  target_link_libraries(cxxabi_static PRIVATE ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
+  target_link_libraries(cxxabi_static PRIVATE cxx-headers ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
   if (TARGET pstl::ParallelSTL)
     target_link_libraries(cxxabi_static PUBLIC pstl::ParallelSTL)
   endif()