diff --git a/contrib/llvm/lib/Target/X86/X86CallFrameOptimization.cpp b/contrib/llvm/lib/Target/X86/X86CallFrameOptimization.cpp
index b16fa76c73f..8f6fc40159e 100644
--- a/contrib/llvm/lib/Target/X86/X86CallFrameOptimization.cpp
+++ b/contrib/llvm/lib/Target/X86/X86CallFrameOptimization.cpp
@@ -125,6 +125,11 @@ bool X86CallFrameOptimization::isLegal(MachineFunction &MF) {
   if (NoX86CFOpt.getValue())
     return false;
 
+  // Work around LLVM PR30879 (bad interaction between CFO and libunwind)
+  if (STI->isTargetFreeBSD() && STI->is32Bit() &&
+      STI->getTargetTriple().getOSMajorVersion() >= 12)
+    return false;
+
   // We can't encode multiple DW_CFA_GNU_args_size or DW_CFA_def_cfa_offset
   // in the compact unwind encoding that Darwin uses. So, bail if there
   // is a danger of that being generated.