Index: clang/cmake/caches/Fuchsia-stage2.cmake
===================================================================
--- clang/cmake/caches/Fuchsia-stage2.cmake
+++ clang/cmake/caches/Fuchsia-stage2.cmake
@@ -57,6 +57,9 @@
       set(RUNTIMES_${target}-linux-gnu_LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
       set(RUNTIMES_${target}-linux-gnu_LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
       set(RUNTIMES_${target}-linux-gnu_LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
+      set(RUNTIMES_${target}-linux-gnu_LIBCXX_ABI_VERSION 2 CACHE STRING "")
+      # TODO: this is a workaround for PR39053 which was uncovered by D50652.
+      set(RUNTIMES_${target}-linux-gnu_LIBCXX_HIDE_FROM_ABI_PER_TU_BY_DEFAULT ON CACHE BOOL "")
       set(RUNTIMES_${target}-linux-gnu_SANITIZER_CXX_ABI "libc++" CACHE STRING "")
       set(RUNTIMES_${target}-linux-gnu_SANITIZER_CXX_ABI_INTREE ON CACHE BOOL "")
       set(RUNTIMES_${target}-linux-gnu_COMPILER_RT_USE_BUILTINS_LIBRARY ON CACHE BOOL "")
@@ -109,6 +112,7 @@
     set(RUNTIMES_${target}-fuchsia_LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
     set(RUNTIMES_${target}-fuchsia_LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
     set(RUNTIMES_${target}-fuchsia_LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-fuchsia_LIBCXX_ABI_VERSION 2 CACHE STRING "")
     # TODO: this is a workaround for PR39053 which was uncovered by D50652.
     set(RUNTIMES_${target}-fuchsia_LIBCXX_HIDE_FROM_ABI_PER_TU_BY_DEFAULT ON CACHE BOOL "")
   endforeach()