Index: lib/Linker/IRMover.cpp
===================================================================
--- lib/Linker/IRMover.cpp
+++ lib/Linker/IRMover.cpp
@@ -1230,8 +1230,20 @@
     case Module::Warning: {
       // Emit a warning if the values differ.
       if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
-        emitWarning("linking module flags '" + ID->getString() +
-                    "': IDs have conflicting values");
+        StringRef IDS = ID->getString();
+        if (IDS == "Dwarf Version")
+          // For conflicting DWARF metadata, print the actual versions
+          // in addition to module names.
+          emitWarning("linking conflicting DWARF versions: v" +
+                      Twine(SrcM->getDwarfVersion()) +
+                      " from " + SrcM->getModuleIdentifier() + " to v" +
+                      Twine(DstM.getDwarfVersion()) + " in "+
+                      DstM.getModuleIdentifier());
+        else
+          emitWarning("linking module flags '" + IDS +
+                      "': IDs have conflicting values (from " +
+                      SrcM->getModuleIdentifier() + " to " +
+                      DstM.getModuleIdentifier() + ")");
       }
       continue;
     }