diff --git a/lldb/source/Plugins/Process/Linux/IntelPTManager.cpp b/lldb/source/Plugins/Process/Linux/IntelPTManager.cpp
--- a/lldb/source/Plugins/Process/Linux/IntelPTManager.cpp
+++ b/lldb/source/Plugins/Process/Linux/IntelPTManager.cpp
@@ -145,7 +145,11 @@
 }
 
 size_t IntelPTThreadTrace::GetTraceBufferSize() const {
+#ifndef PERF_ATTR_SIZE_VER5
+  llvm_unreachable("Intel PT Linux perf event not supported");
+#else
   return m_mmap_meta->aux_size;
+#endif
 }
 
 static Expected<uint64_t>