diff --git a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
--- a/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -65,6 +65,16 @@
       ERROR_FILE /dev/null
     )
   endif()
+  # Finally, use xcrun in case XCode is not installed.
+  if((NOT ${result_process} EQUAL 0) OR "" STREQUAL "${var_internal}")
+    execute_process(
+            COMMAND  xcrun --sdk ${sdk_name} --show-sdk-version
+            RESULT_VARIABLE result_process
+            OUTPUT_VARIABLE var_internal
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_FILE /dev/null
+    )
+  endif()
   if(NOT result_process EQUAL 0)
     message(FATAL_ERROR
       "Failed to determine SDK version for \"${sdk_name}\" SDK")