diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -372,9 +372,9 @@
       if (!AppendNonCUDies)
         break;
       // The average bytes per DIE entry has been seen to be
-      // around 14-20 so let's pre-reserve the needed memory for
+      // around 6-12 so let's pre-reserve the needed memory for
       // our DIE entries accordingly.
-      Dies.reserve(Dies.size() + getDebugInfoSize() / 14);
+      Dies.reserve(Dies.size() + getDebugInfoSize() / 6);
       IsCUDie = false;
     } else {
       Dies.push_back(DIE);
@@ -394,6 +394,8 @@
     }
   }
 
+  Dies.shrink_to_fit();
+
   // Give a little bit of info if we encounter corrupt DWARF (our offset
   // should always terminate at or before the start of the next compilation
   // unit header).