Index: llvm/trunk/runtimes/CMakeLists.txt
===================================================================
--- llvm/trunk/runtimes/CMakeLists.txt
+++ llvm/trunk/runtimes/CMakeLists.txt
@@ -128,6 +128,12 @@
     string(REPLACE "-" "_" canon_name ${projName})
     string(TOUPPER ${canon_name} canon_name)
 
+    # The subdirectories need to treat this as standalone builds. D57992 tried
+    # to get rid of this, but the runtimes treat *_STANDALONE_BUILD=OFF as if
+    # llvm & clang are configured in the same CMake, and setup dependencies
+    # against their targets.
+    set(${canon_name}_STANDALONE_BUILD ON)
+
     if(LLVM_RUNTIMES_LIBDIR_SUBDIR)
       set(${canon_name}_LIBDIR_SUBDIR "${LLVM_RUNTIMES_LIBDIR_SUBDIR}" CACHE STRING "" FORCE)
     endif()