Index: llvm-toolchain-snapshot_21~++20250715030935+8226fbee4b62/compiler-rt/lib/builtins/CMakeLists.txt
===================================================================
--- llvm-toolchain-snapshot_21~++20250715030935+8226fbee4b62.orig/compiler-rt/lib/builtins/CMakeLists.txt
+++ llvm-toolchain-snapshot_21~++20250715030935+8226fbee4b62/compiler-rt/lib/builtins/CMakeLists.txt
@@ -1039,6 +1039,12 @@ if (COMPILER_RT_BUILD_CRT)
     append_list_if(COMPILER_RT_ENABLE_CET -fcf-protection=full CRT_CFLAGS)
   endif()
 
+  if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "x86_64")
+    append_list_if(COMPILER_RT_HAS_FLOAT16 -msse2 -DCOMPILER_RT_HAS_FLOAT16 BUILTIN_CFLAGS)
+  else ()
+    append_list_if(COMPILER_RT_HAS_FLOAT16 -DCOMPILER_RT_HAS_FLOAT16 BUILTIN_CFLAGS)
+  endif()
+
   foreach(arch ${BUILTIN_SUPPORTED_ARCH})
     add_compiler_rt_runtime(clang_rt.crtbegin
       OBJECT