Index: lld/ELF/LTO.cpp
===================================================================
--- lld/ELF/LTO.cpp
+++ lld/ELF/LTO.cpp
@@ -62,6 +62,10 @@
 // flush buffered data to reduce memory consumption. If this fails, open a file
 // stream that supports only write.
 static std::unique_ptr<raw_fd_ostream> openLTOOutputFile(StringRef file) {
+  // Don't flush bitcode incrementally if the output is a special file.
+  // This handles things like '-o /dev/null'
+  if (!sys::fs::is_regular_file(file))
+    return openFile(file);
   std::error_code ec;
   std::unique_ptr<raw_fd_ostream> fs =
       std::make_unique<raw_fd_stream>(file, ec);