Index: COFF/Driver.cpp
===================================================================
--- COFF/Driver.cpp
+++ COFF/Driver.cpp
@@ -83,7 +83,7 @@
 static std::string getOutputPath(StringRef Path) {
   auto P = Path.find_last_of("\\/");
   StringRef S = (P == StringRef::npos) ? Path : Path.substr(P + 1);
-  const char* E = Config->DLL ? ".dll" : ".exe";
+  const char *E = Config->DLL ? ".dll" : ".exe";
   return (S.substr(0, S.rfind('.')) + E).str();
 }
 
@@ -187,7 +187,9 @@
                                     StringRef ParentName) {
   file_magic Magic = identify_magic(MB.getBuffer());
   if (Magic == file_magic::coff_import_library) {
-    Symtab->addFile(make<ImportFile>(MB));
+    InputFile *Imp = make<ImportFile>(MB);
+    Imp->ParentName = ParentName;
+    Symtab->addFile(Imp);
     return;
   }
 
@@ -834,8 +836,7 @@
     if (Set.count(S) == 0) {
       if (Config->WarnMissingOrderSymbol)
         warn("/order:" + Arg + ": missing symbol: " + S + " [LNK4037]");
-    }
-    else
+    } else
       Config->Order[S] = INT_MIN + Config->Order.size();
   }
 }
@@ -1500,7 +1501,8 @@
       E.Name = Def->getName();
       E.Sym = Def;
       if (Def->getChunk() &&
-          !(Def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
+          !(Def->getChunk()->getOutputCharacteristics() &
+            IMAGE_SCN_MEM_EXECUTE))
         E.Data = true;
       Config->Exports.push_back(E);
     });
Index: COFF/PDB.cpp
===================================================================
--- COFF/PDB.cpp
+++ COFF/PDB.cpp
@@ -101,6 +101,9 @@
   /// Link CodeView from each object file in the symbol table into the PDB.
   void addObjectsToPDB();
 
+  /// Link info for each import file in the symbol table into the PDB.
+  void addImportFilesToPDB();
+
   /// Link CodeView from a single object file into the PDB.
   void addObjFile(ObjFile *File);
 
@@ -115,11 +118,11 @@
   /// If the object does not use a type server PDB (compiled with /Z7), we merge
   /// all the type and item records from the .debug$S stream and fill in the
   /// caller-provided ObjectIndexMap.
-  Expected<const CVIndexMap&> mergeDebugT(ObjFile *File,
-                                          CVIndexMap &ObjectIndexMap);
+  Expected<const CVIndexMap &> mergeDebugT(ObjFile *File,
+                                           CVIndexMap &ObjectIndexMap);
 
-  Expected<const CVIndexMap&> maybeMergeTypeServerPDB(ObjFile *File,
-                                                      TypeServer2Record &TS);
+  Expected<const CVIndexMap &> maybeMergeTypeServerPDB(ObjFile *File,
+                                                       TypeServer2Record &TS);
 
   /// Add the section map and section contributions to the PDB.
   void addSections(ArrayRef<OutputSection *> OutputSections,
@@ -256,8 +259,8 @@
   return std::move(TS);
 }
 
-Expected<const CVIndexMap&> PDBLinker::mergeDebugT(ObjFile *File,
-                                                   CVIndexMap &ObjectIndexMap) {
+Expected<const CVIndexMap &>
+PDBLinker::mergeDebugT(ObjFile *File, CVIndexMap &ObjectIndexMap) {
   ScopedTimer T(TypeMergingTimer);
 
   ArrayRef<uint8_t> Data = getDebugSection(File, ".debug$T");
@@ -332,15 +335,15 @@
   return std::move(NS);
 }
 
-Expected<const CVIndexMap&> PDBLinker::maybeMergeTypeServerPDB(ObjFile *File,
-                                                               TypeServer2Record &TS) {
-  const GUID& TSId = TS.getGuid();
+Expected<const CVIndexMap &>
+PDBLinker::maybeMergeTypeServerPDB(ObjFile *File, TypeServer2Record &TS) {
+  const GUID &TSId = TS.getGuid();
   StringRef TSPath = TS.getName();
 
   // First, check if the PDB has previously failed to load.
   if (MissingTypeServerPDBs.count(TSId))
     return make_error<pdb::GenericError>(
-      pdb::generic_error_code::type_server_not_found, TSPath);
+        pdb::generic_error_code::type_server_not_found, TSPath);
 
   // Second, check if we already loaded a PDB with this GUID. Return the type
   // index mapping if we have it.
@@ -361,8 +364,8 @@
     StringRef LocalPath =
         !File->ParentName.empty() ? File->ParentName : File->getName();
     SmallString<128> Path = sys::path::parent_path(LocalPath);
-    sys::path::append(
-        Path, sys::path::filename(TSPath, sys::path::Style::windows));
+    sys::path::append(Path,
+                      sys::path::filename(TSPath, sys::path::Style::windows));
     ExpectedSession = tryToLoadPDB(TSId, Path);
   }
   if (auto E = ExpectedSession.takeError()) {
@@ -1000,6 +1003,44 @@
   }
 }
 
+// Add all import files as modules to the PDB.
+void PDBLinker::addImportFilesToPDB() {
+  // Gather unique import files first.
+  std::vector<ImportFile *> ImpFiles;
+  ImpFiles.reserve(ImportFile::Instances.size());
+
+  std::unordered_set<std::string> UniqueImpFiles;
+  for (ImportFile *File : ImportFile::Instances) {
+    const auto &InsertIt = UniqueImpFiles.insert(File->DLLName);
+    if (InsertIt.second) {
+      // Found a new unique import file.
+      ImpFiles.push_back(File);
+    }
+  }
+
+  // Now walk all import files and add them as modules to the PDB.
+  for (ImportFile *File : ImpFiles) {
+    SmallString<128> LibPath = File->ParentName;
+    sys::fs::make_absolute(LibPath);
+    sys::path::native(LibPath, sys::path::Style::windows);
+
+    // Name modules similar to MSVC's link.exe.
+    SmallString<128> Name = "Import:" + File->DLLName;
+
+    llvm::pdb::DbiModuleDescriptorBuilder *ModuleDBI =
+        &ExitOnErr(Builder.getDbiBuilder().addModuleInfo(Name));
+    ModuleDBI->setObjFileName(LibPath);
+    ExitOnErr(Builder.getDbiBuilder().addModuleSourceFile(*ModuleDBI, Name));
+
+    ObjNameSym ONS(SymbolRecordKind::ObjNameSym);
+    ONS.Name = File->DLLName;
+    ONS.Signature = 0;
+
+    ModuleDBI->addSymbol(codeview::SymbolSerializer::writeOneSymbol(
+        ONS, Alloc, CodeViewContainer::Pdb));
+  }
+}
+
 void PDBLinker::addNatvisFiles() {
   for (StringRef File : Config->NatvisFiles) {
     ErrorOr<std::unique_ptr<MemoryBuffer>> DataOrErr =
@@ -1109,6 +1150,7 @@
 
   PDB.initialize(BuildId);
   PDB.addObjectsToPDB();
+  PDB.addImportFilesToPDB();
   PDB.addSections(OutputSections, SectionTable);
   PDB.addNatvisFiles();