Index: lib/DebugInfo/DWARF/DWARFDebugLine.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -520,6 +520,15 @@
     // rudimentary sequences for address ranges [0x0, 0xsomething).
   }
 
+  // There could be hundreds or thousands of Rows in the line table. The vector
+  // will likely have an internal reserved memory block that is much bigger
+  // than necessary. Copy the contents to a block of memory with the exact size
+  // (or as exact as the allocator will allow).
+  std::vector<DWARFDebugLine::Row> compactRows;
+  compactRows.reserve(Rows.size());
+  std::copy(Rows.begin(), Rows.end(), compactRows.begin());
+  Rows = std::move(compactRows);
+
   return end_offset;
 }