Index: lld/MinGW/Driver.cpp
===================================================================
--- lld/MinGW/Driver.cpp
+++ lld/MinGW/Driver.cpp
@@ -6,9 +6,27 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-///
-/// GNU ld style linker driver for COFF currently supporting mingw-w64.
-///
+//
+// MinGW is a GNU development environment for Windows. It consists with GNU
+// tools such as GCC and GNU ld. Unlike Cygwin, there's no POSIX-compatible
+// layer, as it aims to be a native development toolchain.
+//
+// lld/MinGW is a drop-in replacement for GNU ld/MinGW.
+//
+// Being a native development tool, a MinGW linker is not very differnet from
+// Microsoft link.exe, so a MinGW linker can be implemented as a thin wrapper
+// for lld/COFF. This driver takes Unix-ish command line options, translate them
+// to Windows-ish ones, and then pass them to lld/COFF.
+//
+// When this driver calls lld/COFF driver, it passes a hidden option "-lldmingw"
+// along with other user-supplied options, to run lld/COFF linker in "MinGW
+// mode".
+//
+// There are subtle differences between MS link.exe and GNU ld/MinGW, and GNU
+// ld/MinGW implemented a few GNU-specific features. Such features are directly
+// implemented in lld/COFF and enabled only when in the linker is running in
+// MinGW mode.
+//
 //===----------------------------------------------------------------------===//
 
 #include "lld/Common/Driver.h"