Index: libcxx/CMakeLists.txt
===================================================================
--- libcxx/CMakeLists.txt
+++ libcxx/CMakeLists.txt
@@ -866,6 +866,19 @@
   config_define(ON _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
 endif()
 
+if (WIN32 AND LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
+  if (LIBCXX_ENABLE_SHARED AND LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
+    # If linking libcxxabi statically into a shared libcxx, change declarations
+    # as if we are part of the libcxxabi, to make declarations dllexport
+    # instead of dllimport.
+    add_definitions(-D_LIBCXXABI_BUILDING_LIBRARY)
+  elseif(LIBCXX_ENABLE_STATIC AND LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY)
+    # If linking libcxxabi statically into a static libcxx, skip the dllimport
+    # attributes on symbols we refer to from libcxxabi.
+    add_definitions(-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
+  endif()
+endif()
+
 # Setup all common build flags =================================================
 function(cxx_add_common_build_flags target)
   cxx_add_basic_build_flags(${target})
Index: libcxxabi/CMakeLists.txt
===================================================================
--- libcxxabi/CMakeLists.txt
+++ libcxxabi/CMakeLists.txt
@@ -281,7 +281,18 @@
 
 # Disable DLL annotations on Windows for static builds.
 if (WIN32 AND LIBCXXABI_ENABLE_STATIC AND NOT LIBCXXABI_ENABLE_SHARED)
-  add_definitions(-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
+  if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
+    # Building libcxxabi statically, but intending for it to be statically
+    # linked into a shared libcxx; keep dllexport enabled within libcxxabi,
+    # and treat libcxx imports in the same way as if we were building libcxx
+    # itself (make them dllexport instead of dllimport).
+    # Define to the empty string (if just defined as -DFOO, it defines it to
+    # the value 1) as we have a number of "#define _LIBCPP_BUILDING_LIBRARY"
+    # in certain source files.
+    add_definitions(-D_LIBCPP_BUILDING_LIBRARY=)
+  else()
+    add_definitions(-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
+  endif()
 endif()
 
 add_compile_flags_if_supported(-Werror=return-type)