Index: COFF/InputFiles.h
===================================================================
--- COFF/InputFiles.h
+++ COFF/InputFiles.h
@@ -128,9 +128,6 @@
   // Returns the underlying COFF file.
   COFFObjectFile *getCOFFObj() { return COFFObj.get(); }
 
-  // Whether the object was already merged into the final PDB or not
-  bool wasProcessedForPDB() const { return !!ModuleDBI; }
-
   static std::vector<ObjFile *> Instances;
 
   // Flags in the absolute @feat.00 symbol if it is present. These usually
@@ -161,6 +158,9 @@
   // Tells whether this file was compiled with /hotpatch
   bool HotPatchable = false;
 
+  // Whether the object was already merged into the final PDB or not
+  bool Merged = false;
+
 private:
   const coff_section* getSection(uint32_t I);
   const coff_section *getSection(COFFSymbolRef Sym) {
Index: COFF/PDB.cpp
===================================================================
--- COFF/PDB.cpp
+++ COFF/PDB.cpp
@@ -1212,32 +1212,56 @@
   File.ModuleDBI->addDebugSubsection(std::move(NewChecksums));
 }
 
-void PDBLinker::addObjFile(ObjFile *File, CVIndexMap *ExternIndexMap) {
-  if (File->wasProcessedForPDB())
-    return;
-  // Add a module descriptor for every object file. We need to put an absolute
-  // path to the object into the PDB. If this is a plain object, we make its
-  // path absolute. If it's an object in an archive, we make the archive path
-  // absolute.
+static StringRef getModObjName(InputFile *File, SmallVectorImpl<char> &ObjName) {
   bool InArchive = !File->ParentName.empty();
-  SmallString<128> Path = InArchive ? File->ParentName : File->getName();
-  pdbMakeAbsolute(Path);
-  StringRef Name = InArchive ? File->getName() : StringRef(Path);
+  StringRef Name = InArchive ? File->ParentName : File->getName();
+  ObjName.assign(Name.begin(), Name.end());
+  pdbMakeAbsolute(ObjName);
+  StringRef ModName =
+      InArchive ? File->getName() : StringRef(ObjName.data(), ObjName.size());
+  return ModName;
+}
 
+// Add a module descriptor for every object file. We need to put an absolute
+// path to the object into the PDB. If this is a plain object, we make its
+// path absolute. If it's an object in an archive, we make the archive path
+// absolute.
+static void createModuleDBI(pdb::PDBFileBuilder &Builder) {
   pdb::DbiStreamBuilder &DbiBuilder = Builder.getDbiBuilder();
-  File->ModuleDBI = &ExitOnErr(DbiBuilder.addModuleInfo(Name));
-  File->ModuleDBI->setObjFileName(Path);
+  SmallString<128> ObjName;
+  for (ObjFile *File : ObjFile::Instances) {
+    StringRef ModName = getModObjName(File, ObjName);
+    File->ModuleDBI = &ExitOnErr(DbiBuilder.addModuleInfo(ModName));
+    File->ModuleDBI->setObjFileName(ObjName);
+    ArrayRef<Chunk *> Chunks = File->getChunks();
+    uint32_t Modi = File->ModuleDBI->getModuleIndex();
+    for (Chunk *C : Chunks) {
+      auto *SecChunk = dyn_cast<SectionChunk>(C);
+      if (!SecChunk || !SecChunk->Live)
+        continue;
+      pdb::SectionContrib SC = createSectionContrib(SecChunk, Modi);
+      File->ModuleDBI->setFirstSectionContrib(SC);
+      break;
+    }
+  }
+}
 
-  auto Chunks = File->getChunks();
-  uint32_t Modi = File->ModuleDBI->getModuleIndex();
-  for (Chunk *C : Chunks) {
-    auto *SecChunk = dyn_cast<SectionChunk>(C);
-    if (!SecChunk || !SecChunk->Live)
-      continue;
-    pdb::SectionContrib SC = createSectionContrib(SecChunk, Modi);
-    File->ModuleDBI->setFirstSectionContrib(SC);
-    break;
+static void warnUnusable(InputFile *F, Error E) {
+  if (!Config->WarnDebugInfoUnusable) {
+    consumeError(std::move(E));
+    return;
   }
+  auto Msg = "Cannot use debug info for '" + toString(F) + "' [LNK4099]";
+  if (E)
+    warn(Msg + "\n>>> failed to load reference " + toString(std::move(E)));
+  else
+    warn(Msg);
+}
+
+void PDBLinker::addObjFile(ObjFile *File, CVIndexMap *ExternIndexMap) {
+  if (File->Merged)
+    return;
+  File->Merged = true;
 
   // Before we can process symbol substreams from .debug$S, we need to process
   // type information, file checksums, and the string table.  Add type info to
@@ -1249,19 +1273,13 @@
 
   // If the .debug$T sections fail to merge, assume there is no debug info.
   if (!IndexMapResult) {
-    if (!Config->WarnDebugInfoUnusable) {
-      consumeError(IndexMapResult.takeError());
-      return;
-    }
-    StringRef FileName = sys::path::filename(Path);
-    warn("Cannot use debug info for '" + FileName + "' [LNK4099]\n" +
-         ">>> failed to load reference " +
-         StringRef(toString(IndexMapResult.takeError())));
+    warnUnusable(File, IndexMapResult.takeError());
     return;
   }
 
   ScopedTimer T(SymbolMergingTimer);
 
+  pdb::DbiStreamBuilder &DbiBuilder = Builder.getDbiBuilder();
   DebugSHandler DSH(*this, *File, *IndexMapResult);
   // Now do all live .debug$S and .debug$F sections.
   for (SectionChunk *DebugChunk : File->getDebugChunks()) {
@@ -1315,6 +1333,9 @@
 // TpiData.
 void PDBLinker::addObjectsToPDB() {
   ScopedTimer T1(AddObjectsTimer);
+
+  createModuleDBI(Builder);
+
   for (ObjFile *File : ObjFile::Instances)
     addObjFile(File);