add a 'don't use me' marker.

llvm-svn: 43226
diff --git a/llvm/tools/llvmc/llvmc.cpp b/llvm/tools/llvmc/llvmc.cpp
index dc78397..d45083e 100644
--- a/llvm/tools/llvmc/llvmc.cpp
+++ b/llvm/tools/llvmc/llvmc.cpp
@@ -253,6 +253,9 @@
   // Make sure we print stack trace if we get bad signals
   sys::PrintStackTraceOnErrorSignal();
 
+  std::cout << "NOTE: llvmc is highly experimental and mostly useless right "
+               "now.\nPlease use llvm-gcc directly instead.\n\n";
+
   try {
 
     // Parse the command line options