Index: compiler-rt/test/lit.common.configured.in
===================================================================
--- compiler-rt/test/lit.common.configured.in
+++ compiler-rt/test/lit.common.configured.in
@@ -49,6 +49,7 @@
   set_default("target_suffix", "-%s" % config.target_arch)
 
 set_default("have_zlib", "@HAVE_LIBZ@")
+set_default("libcxx_used", "@LLVM_LIBCXX_USED@")
 
 # LLVM tools dir can be passed in lit parameters, so try to
 # apply substitution.
Index: compiler-rt/test/xray/lit.cfg
===================================================================
--- compiler-rt/test/xray/lit.cfg
+++ compiler-rt/test/xray/lit.cfg
@@ -10,8 +10,16 @@
 
 # Setup default compiler flags use with -fxray-instrument option.
 clang_xray_cflags = (['-fxray-instrument', config.target_cflags])
-clang_xray_cxxflags = config.cxx_mode_flags + clang_xray_cflags
 
+# If libc++ was used to build XRAY libraries, libc++ is needed. Fix applied
+# to Linux only since -rpath may not be portable. This can be extended to
+# other platforms.
+if config.libcxx_used == "1" and config.host_os == "Linux":
+  clang_xray_cflags = clang_xray_cflags + (['-L%s -lc++ -Wl,-rpath=%s'
+                                          % (config.llvm_shlib_dir,
+                                             config.llvm_shlib_dir)])
+
+clang_xray_cxxflags = config.cxx_mode_flags + clang_xray_cflags
 
 def build_invocation(compile_flags):
   return ' ' + ' '.join([config.clang] + compile_flags) + ' '
Index: llvm/cmake/modules/HandleLLVMStdlib.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMStdlib.cmake
+++ llvm/cmake/modules/HandleLLVMStdlib.cmake
@@ -14,6 +14,7 @@
 
   include(CheckCXXCompilerFlag)
   include(CheckLinkerFlag)
+  set(LLVM_LIBCXX_USED 0)
   if(LLVM_ENABLE_LIBCXX)
     if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
       check_cxx_compiler_flag("-stdlib=libc++" CXX_COMPILER_SUPPORTS_STDLIB)
@@ -22,6 +23,7 @@
         append("-stdlib=libc++"
           CMAKE_CXX_FLAGS CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS
           CMAKE_MODULE_LINKER_FLAGS)
+        set(LLVM_LIBCXX_USED 1)
       else()
         message(WARNING "Can't specify libc++ with '-stdlib='")
       endif()