Index: llvm/cmake/config-ix.cmake
===================================================================
--- llvm/cmake/config-ix.cmake
+++ llvm/cmake/config-ix.cmake
@@ -213,7 +213,12 @@
 
 check_library_exists(xar xar_open "" LLVM_HAVE_LIBXAR)
 if(LLVM_HAVE_LIBXAR)
-  set(XAR_LIB xar)
+  # The xar file format has been deprecated since macOS 12.0.
+  if (CMAKE_OSX_DEPLOYMENT_TARGET VERSION_GREATER_EQUAL 12)
+    set(LLVM_HAVE_LIBXAR 0)
+  else()
+    set(XAR_LIB xar)
+  endif()
 endif()
 
 # function checks