diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -525,7 +525,7 @@
     }
 
     const MCDwarfLineTable &getMCDwarfLineTable(unsigned CUID) const {
-      auto I = MCDwarfLineTablesCUMap.find(CUID);
+      const auto &I = MCDwarfLineTablesCUMap.find(CUID);
       assert(I != MCDwarfLineTablesCUMap.end());
       return I->second;
     }
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -1911,7 +1911,7 @@
   // Emit the label for the line table, if requested - since the rest of the
   // line table will be defined by .loc/.file directives, and not emitted
   // directly, the label is the only work required here.
-  auto &Tables = getContext().getMCDwarfLineTables();
+  const auto &Tables = getContext().getMCDwarfLineTables();
   if (!Tables.empty()) {
     assert(Tables.size() == 1 && "asm output only supports one line table");
     if (auto *Label = Tables.begin()->second.getLabel()) {