diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 3276575..945fba8 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1511,6 +1511,8 @@
                                        MF->getFunction()->getContext());
     recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
                      FnStartDL.getScope(MF->getFunction()->getContext()),
+    // We'd like to list the prologue as "not statements" but GDB behaves
+    // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
                      DWARF2_FLAG_IS_STMT);
   }
 }