Index: include/llvm/Object/ArchiveWriter.h
===================================================================
--- include/llvm/Object/ArchiveWriter.h
+++ include/llvm/Object/ArchiveWriter.h
@@ -20,27 +20,20 @@
 
 namespace llvm {
 
-class NewArchiveIterator {
-  bool IsNewMember;
-  StringRef Name;
-
-  object::Archive::Child OldMember;
-
-public:
-  NewArchiveIterator(const object::Archive::Child &OldMember, StringRef Name);
-  NewArchiveIterator(StringRef FileName);
-  bool isNewMember() const;
-  StringRef getName() const;
-
-  const object::Archive::Child &getOld() const;
-
-  StringRef getNew() const;
-  llvm::ErrorOr<int> getFD(sys::fs::file_status &NewStatus) const;
-  const sys::fs::file_status &getStatus() const;
+struct NewArchiveMember {
+  std::unique_ptr<MemoryBuffer> Buf;
+  sys::TimeValue ModTime = sys::TimeValue::PosixZeroTime();
+  unsigned UID = 0, GID = 0, Perms = 0644;
+
+  NewArchiveMember() = default;
+  NewArchiveMember(MemoryBufferRef BufRef);
+  NewArchiveMember(const object::Archive::Child &OldMember, bool Deterministic,
+                   std::error_code &EC);
+  NewArchiveMember(StringRef FileName, bool Deterministic, std::error_code &EC);
 };
 
 std::pair<StringRef, std::error_code>
-writeArchive(StringRef ArcName, std::vector<NewArchiveIterator> &NewMembers,
+writeArchive(StringRef ArcName, std::vector<NewArchiveMember> &NewMembers,
              bool WriteSymtab, object::Archive::Kind Kind, bool Deterministic,
              bool Thin, std::unique_ptr<MemoryBuffer> OldArchiveBuf = nullptr);
 }
Index: lib/LibDriver/LibDriver.cpp
===================================================================
--- lib/LibDriver/LibDriver.cpp
+++ lib/LibDriver/LibDriver.cpp
@@ -57,10 +57,10 @@
 }
 
 static std::string getOutputPath(llvm::opt::InputArgList *Args,
-                                 const llvm::NewArchiveIterator &FirstMember) {
+                                 const llvm::NewArchiveMember &FirstMember) {
   if (auto *Arg = Args->getLastArg(OPT_out))
     return Arg->getValue();
-  SmallString<128> Val = FirstMember.getNew();
+  SmallString<128> Val = StringRef(FirstMember.Buf->getBufferIdentifier());
   llvm::sys::path::replace_extension(Val, ".lib");
   return Val.str();
 }
@@ -128,14 +128,19 @@
 
   std::vector<StringRef> SearchPaths = getSearchPaths(&Args, Saver);
 
-  std::vector<llvm::NewArchiveIterator> Members;
+  std::vector<llvm::NewArchiveMember> Members;
   for (auto *Arg : Args.filtered(OPT_INPUT)) {
     Optional<std::string> Path = findInputFile(Arg->getValue(), SearchPaths);
     if (!Path.hasValue()) {
       llvm::errs() << Arg->getValue() << ": no such file or directory\n";
       return 1;
     }
-    Members.emplace_back(Saver.save(*Path));
+    std::error_code EC;
+    Members.emplace_back(Saver.save(*Path), /*Deterministic=*/true, EC);
+    if (EC) {
+      llvm::errs() << Arg->getValue() << ": " << EC.message() << "\n";
+      return 1;
+    }
   }
 
   std::pair<StringRef, std::error_code> Result =
Index: lib/Object/ArchiveWriter.cpp
===================================================================
--- lib/Object/ArchiveWriter.cpp
+++ lib/Object/ArchiveWriter.cpp
@@ -34,45 +34,63 @@
 
 using namespace llvm;
 
-NewArchiveIterator::NewArchiveIterator(const object::Archive::Child &OldMember,
-                                       StringRef Name)
-    : IsNewMember(false), Name(Name), OldMember(OldMember) {}
-
-NewArchiveIterator::NewArchiveIterator(StringRef FileName)
-    : IsNewMember(true), Name(FileName), OldMember(nullptr, nullptr, nullptr) {}
-
-StringRef NewArchiveIterator::getName() const { return Name; }
-
-bool NewArchiveIterator::isNewMember() const { return IsNewMember; }
-
-const object::Archive::Child &NewArchiveIterator::getOld() const {
-  assert(!IsNewMember);
-  return OldMember;
-}
-
-StringRef NewArchiveIterator::getNew() const {
-  assert(IsNewMember);
-  return Name;
+NewArchiveMember::NewArchiveMember(MemoryBufferRef BufRef)
+    : Buf(MemoryBuffer::getMemBuffer(BufRef, false)) {}
+
+NewArchiveMember::NewArchiveMember(const object::Archive::Child &OldMember,
+                                   bool Deterministic, std::error_code &EC) {
+  ErrorOr<llvm::MemoryBufferRef> BufOrErr = OldMember.getMemoryBufferRef();
+  if (!BufOrErr) {
+    EC = BufOrErr.getError();
+    return;
+  }
+  Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
+  if (!Deterministic) {
+    ModTime = OldMember.getLastModified();
+    UID = OldMember.getUID();
+    GID = OldMember.getGID();
+    Perms = OldMember.getAccessMode();
+  }
 }
 
-llvm::ErrorOr<int>
-NewArchiveIterator::getFD(sys::fs::file_status &NewStatus) const {
-  assert(IsNewMember);
-  int NewFD;
-  if (auto EC = sys::fs::openFileForRead(Name, NewFD))
-    return EC;
-  assert(NewFD != -1);
+NewArchiveMember::NewArchiveMember(StringRef FileName, bool Deterministic,
+                                   std::error_code &EC) {
+  sys::fs::file_status Status;
+  int FD;
+  if ((EC = sys::fs::openFileForRead(FileName, FD)))
+    return;
+  assert(FD != -1);
 
-  if (auto EC = sys::fs::status(NewFD, NewStatus))
-    return EC;
+  if ((EC = sys::fs::status(FD, Status)))
+    return;
 
   // Opening a directory doesn't make sense. Let it fail.
   // Linux cannot open directories with open(2), although
   // cygwin and *bsd can.
-  if (NewStatus.type() == sys::fs::file_type::directory_file)
-    return make_error_code(errc::is_a_directory);
+  if (Status.type() == sys::fs::file_type::directory_file) {
+    EC = make_error_code(errc::is_a_directory);
+    return;
+  }
 
-  return NewFD;
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
+      MemoryBuffer::getOpenFile(FD, FileName, Status.getSize(), false);
+  if (!MemberBufferOrErr) {
+    EC = MemberBufferOrErr.getError();
+    return;
+  }
+
+  if (close(FD) != 0) {
+    EC = std::error_code(errno, std::generic_category());
+    return;
+  }
+
+  Buf = std::move(*MemberBufferOrErr);
+  if (!Deterministic) {
+    ModTime = Status.getLastModificationTime();
+    UID = Status.getUser();
+    GID = Status.getGroup();
+    Perms = Status.permissions();
+  }
 }
 
 template <typename T>
@@ -178,12 +196,13 @@
 }
 
 static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
-                             ArrayRef<NewArchiveIterator> Members,
+                             ArrayRef<NewArchiveMember> Members,
                              std::vector<unsigned> &StringMapIndexes,
                              bool Thin) {
   unsigned StartOffset = 0;
-  for (const NewArchiveIterator &I : Members) {
-    StringRef Name = sys::path::filename(I.getName());
+  for (const NewArchiveMember &M : Members) {
+    StringRef Path = M.Buf->getBufferIdentifier();
+    StringRef Name = sys::path::filename(Path);
     if (!useStringTable(Thin, Name))
       continue;
     if (StartOffset == 0) {
@@ -194,7 +213,7 @@
     StringMapIndexes.push_back(Out.tell() - StartOffset);
 
     if (Thin)
-      Out << computeRelativePath(ArcName, I.getName());
+      Out << computeRelativePath(ArcName, Path);
     else
       Out << Name;
 
@@ -221,8 +240,7 @@
 // Returns the offset of the first reference to a member offset.
 static ErrorOr<unsigned>
 writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
-                 ArrayRef<NewArchiveIterator> Members,
-                 ArrayRef<MemoryBufferRef> Buffers,
+                 ArrayRef<NewArchiveMember> Members,
                  std::vector<unsigned> &MemberOffsetRefs, bool Deterministic) {
   unsigned HeaderStartOffset = 0;
   unsigned BodyStartOffset = 0;
@@ -230,7 +248,7 @@
   raw_svector_ostream NameOS(NameBuf);
   LLVMContext Context;
   for (unsigned MemberNum = 0, N = Members.size(); MemberNum < N; ++MemberNum) {
-    MemoryBufferRef MemberBuffer = Buffers[MemberNum];
+    MemoryBufferRef MemberBuffer = Members[MemberNum].Buf->getMemBufferRef();
     Expected<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
         object::SymbolicFile::createSymbolicFile(
             MemberBuffer, sys::fs::file_magic::unknown, &Context);
@@ -305,7 +323,7 @@
 
 std::pair<StringRef, std::error_code>
 llvm::writeArchive(StringRef ArcName,
-                   std::vector<NewArchiveIterator> &NewMembers,
+                   std::vector<NewArchiveMember> &NewMembers,
                    bool WriteSymtab, object::Archive::Kind Kind,
                    bool Deterministic, bool Thin,
                    std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
@@ -330,43 +348,10 @@
   std::vector<MemoryBufferRef> Members;
   std::vector<sys::fs::file_status> NewMemberStatus;
 
-  for (NewArchiveIterator &Member : NewMembers) {
-    MemoryBufferRef MemberRef;
-
-    if (Member.isNewMember()) {
-      StringRef Filename = Member.getNew();
-      NewMemberStatus.resize(NewMemberStatus.size() + 1);
-      sys::fs::file_status &Status = NewMemberStatus.back();
-      ErrorOr<int> FD = Member.getFD(Status);
-      if (auto EC = FD.getError())
-        return std::make_pair(Filename, EC);
-      ErrorOr<std::unique_ptr<MemoryBuffer>> MemberBufferOrErr =
-          MemoryBuffer::getOpenFile(FD.get(), Filename, Status.getSize(),
-                                    false);
-      if (auto EC = MemberBufferOrErr.getError())
-        return std::make_pair(Filename, EC);
-      if (close(FD.get()) != 0)
-        return std::make_pair(Filename,
-                              std::error_code(errno, std::generic_category()));
-      Buffers.push_back(std::move(MemberBufferOrErr.get()));
-      MemberRef = Buffers.back()->getMemBufferRef();
-    } else {
-      const object::Archive::Child &OldMember = Member.getOld();
-      assert((!Thin || OldMember.getParent()->isThin()) &&
-             "Thin archives cannot refers to member of other archives");
-      ErrorOr<MemoryBufferRef> MemberBufferOrErr =
-          OldMember.getMemoryBufferRef();
-      if (auto EC = MemberBufferOrErr.getError())
-        return std::make_pair("", EC);
-      MemberRef = MemberBufferOrErr.get();
-    }
-    Members.push_back(MemberRef);
-  }
-
   unsigned MemberReferenceOffset = 0;
   if (WriteSymtab) {
     ErrorOr<unsigned> MemberReferenceOffsetOrErr = writeSymbolTable(
-        Out, Kind, NewMembers, Members, MemberOffsetRefs, Deterministic);
+        Out, Kind, NewMembers, MemberOffsetRefs, Deterministic);
     if (auto EC = MemberReferenceOffsetOrErr.getError())
       return std::make_pair(ArcName, EC);
     MemberReferenceOffset = MemberReferenceOffsetOrErr.get();
@@ -376,55 +361,18 @@
   if (Kind != object::Archive::K_BSD)
     writeStringTable(Out, ArcName, NewMembers, StringMapIndexes, Thin);
 
-  unsigned MemberNum = 0;
-  unsigned NewMemberNum = 0;
   std::vector<unsigned>::iterator StringMapIndexIter = StringMapIndexes.begin();
   std::vector<unsigned> MemberOffset;
-  for (const NewArchiveIterator &I : NewMembers) {
-    MemoryBufferRef File = Members[MemberNum++];
+  for (const NewArchiveMember &M : NewMembers) {
+    MemoryBufferRef File = M.Buf->getMemBufferRef();
 
     unsigned Pos = Out.tell();
     MemberOffset.push_back(Pos);
 
-    sys::TimeValue ModTime;
-    unsigned UID;
-    unsigned GID;
-    unsigned Perms;
-    if (Deterministic) {
-      ModTime.fromEpochTime(0);
-      UID = 0;
-      GID = 0;
-      Perms = 0644;
-    } else if (I.isNewMember()) {
-      const sys::fs::file_status &Status = NewMemberStatus[NewMemberNum];
-      ModTime = Status.getLastModificationTime();
-      UID = Status.getUser();
-      GID = Status.getGroup();
-      Perms = Status.permissions();
-    } else {
-      const object::Archive::Child &OldMember = I.getOld();
-      ModTime = OldMember.getLastModified();
-      UID = OldMember.getUID();
-      GID = OldMember.getGID();
-      Perms = OldMember.getAccessMode();
-    }
-
-    if (I.isNewMember()) {
-      StringRef FileName = I.getNew();
-      const sys::fs::file_status &Status = NewMemberStatus[NewMemberNum++];
-      printMemberHeader(Out, Kind, Thin, sys::path::filename(FileName),
-                        StringMapIndexIter, ModTime, UID, GID, Perms,
-                        Status.getSize());
-    } else {
-      const object::Archive::Child &OldMember = I.getOld();
-      ErrorOr<uint32_t> Size = OldMember.getSize();
-      if (std::error_code EC = Size.getError())
-        return std::make_pair("", EC);
-      StringRef FileName = I.getName();
-      printMemberHeader(Out, Kind, Thin, sys::path::filename(FileName),
-                        StringMapIndexIter, ModTime, UID, GID, Perms,
-                        Size.get());
-    }
+    printMemberHeader(Out, Kind, Thin,
+                      sys::path::filename(M.Buf->getBufferIdentifier()),
+                      StringMapIndexIter, M.ModTime, M.UID, M.GID, M.Perms,
+                      M.Buf->getBufferSize());
 
     if (!Thin)
       Out << File.getBuffer();
Index: tools/llvm-ar/llvm-ar.cpp
===================================================================
--- tools/llvm-ar/llvm-ar.cpp
+++ tools/llvm-ar/llvm-ar.cpp
@@ -428,25 +428,28 @@
   std::exit(1);
 }
 
-static void addMember(std::vector<NewArchiveIterator> &Members,
+static void addMember(std::vector<NewArchiveMember> &Members,
                       StringRef FileName, int Pos = -1) {
-  NewArchiveIterator NI(FileName);
+  std::error_code EC;
+  NewArchiveMember NM(FileName, Deterministic, EC);
+  failIfError(EC, FileName);
   if (Pos == -1)
-    Members.push_back(NI);
+    Members.push_back(std::move(NM));
   else
-    Members[Pos] = NI;
+    Members[Pos] = std::move(NM);
 }
 
-static void addMember(std::vector<NewArchiveIterator> &Members,
-                      const object::Archive::Child &M, StringRef Name,
-                      int Pos = -1) {
+static void addMember(std::vector<NewArchiveMember> &Members,
+                      const object::Archive::Child &M, int Pos = -1) {
   if (Thin && !M.getParent()->isThin())
     fail("Cannot convert a regular archive to a thin one");
-  NewArchiveIterator NI(M, Name);
+  std::error_code EC;
+  NewArchiveMember NM(M, Deterministic, EC);
+  failIfError(EC);
   if (Pos == -1)
-    Members.push_back(NI);
+    Members.push_back(std::move(NM));
   else
-    Members[Pos] = NI;
+    Members[Pos] = std::move(NM);
 }
 
 enum InsertAction {
@@ -507,11 +510,11 @@
 
 // We have to walk this twice and computing it is not trivial, so creating an
 // explicit std::vector is actually fairly efficient.
-static std::vector<NewArchiveIterator>
+static std::vector<NewArchiveMember>
 computeNewArchiveMembers(ArchiveOperation Operation,
                          object::Archive *OldArchive) {
-  std::vector<NewArchiveIterator> Ret;
-  std::vector<NewArchiveIterator> Moved;
+  std::vector<NewArchiveMember> Ret;
+  std::vector<NewArchiveMember> Moved;
   int InsertPos = -1;
   StringRef PosName = sys::path::filename(RelPos);
   if (OldArchive) {
@@ -535,7 +538,7 @@
           computeInsertAction(Operation, Child, Name, MemberI);
       switch (Action) {
       case IA_AddOldMember:
-        addMember(Ret, Child, Name);
+        addMember(Ret, Child);
         break;
       case IA_AddNewMeber:
         addMember(Ret, *MemberI);
@@ -543,7 +546,7 @@
       case IA_Delete:
         break;
       case IA_MoveOldMember:
-        addMember(Moved, Child, Name);
+        addMember(Moved, Child);
         break;
       case IA_MoveNewMember:
         addMember(Moved, *MemberI);
@@ -564,10 +567,15 @@
     InsertPos = Ret.size();
 
   assert(unsigned(InsertPos) <= Ret.size());
-  Ret.insert(Ret.begin() + InsertPos, Moved.begin(), Moved.end());
-
-  Ret.insert(Ret.begin() + InsertPos, Members.size(), NewArchiveIterator(""));
   int Pos = InsertPos;
+  for (auto &M : Moved) {
+    Ret.insert(Ret.begin() + Pos, std::move(M));
+    ++Pos;
+  }
+
+  for (unsigned I = 0; I != Members.size(); ++I)
+    Ret.insert(Ret.begin() + InsertPos, NewArchiveMember());
+  Pos = InsertPos;
   for (auto &Member : Members) {
     addMember(Ret, Member, Pos);
     ++Pos;
@@ -581,56 +589,26 @@
                                                       : object::Archive::K_GNU;
 }
 
-static object::Archive::Kind
-getKindFromMember(const NewArchiveIterator &Member) {
-  auto getKindFromMemberInner =
-      [](MemoryBufferRef Buffer) -> object::Archive::Kind {
-    Expected<std::unique_ptr<object::ObjectFile>> OptionalObject =
-        object::ObjectFile::createObjectFile(Buffer);
+static object::Archive::Kind getKindFromMember(const NewArchiveMember &Member) {
+  Expected<std::unique_ptr<object::ObjectFile>> OptionalObject =
+      object::ObjectFile::createObjectFile(Member.Buf->getMemBufferRef());
 
-    if (OptionalObject)
-      return isa<object::MachOObjectFile>(**OptionalObject)
-                 ? object::Archive::K_BSD
-                 : object::Archive::K_GNU;
+  if (OptionalObject)
+    return isa<object::MachOObjectFile>(**OptionalObject)
+               ? object::Archive::K_BSD
+               : object::Archive::K_GNU;
 
-    // squelch the error in case we had a non-object file
-    consumeError(OptionalObject.takeError());
-    return getDefaultForHost();
-  };
-
-  if (Member.isNewMember()) {
-    object::Archive::Kind Kind = getDefaultForHost();
-
-    sys::fs::file_status Status;
-    if (auto OptionalFD = Member.getFD(Status)) {
-      if (auto MB = MemoryBuffer::getOpenFile(*OptionalFD, Member.getName(),
-                                              Status.getSize(), false))
-        Kind = getKindFromMemberInner((*MB)->getMemBufferRef());
-
-      if (close(*OptionalFD) != 0)
-        failIfError(std::error_code(errno, std::generic_category()),
-                    "failed to close file");
-    }
-
-    return Kind;
-  } else {
-    const object::Archive::Child &OldMember = Member.getOld();
-    if (OldMember.getParent()->isThin())
-      return object::Archive::Kind::K_GNU;
-
-    auto OptionalMB = OldMember.getMemoryBufferRef();
-    failIfError(OptionalMB.getError());
-
-    return getKindFromMemberInner(*OptionalMB);
-  }
+  // squelch the error in case we had a non-object file
+  consumeError(OptionalObject.takeError());
+  return getDefaultForHost();
 }
 
 static void
 performWriteOperation(ArchiveOperation Operation,
                       object::Archive *OldArchive,
                       std::unique_ptr<MemoryBuffer> OldArchiveBuf,
-                      std::vector<NewArchiveIterator> *NewMembersP) {
-  std::vector<NewArchiveIterator> NewMembers;
+                      std::vector<NewArchiveMember> *NewMembersP) {
+  std::vector<NewArchiveMember> NewMembers;
   if (!NewMembersP)
     NewMembers = computeNewArchiveMembers(Operation, OldArchive);
 
@@ -680,7 +658,7 @@
 static void performOperation(ArchiveOperation Operation,
                              object::Archive *OldArchive,
                              std::unique_ptr<MemoryBuffer> OldArchiveBuf,
-                             std::vector<NewArchiveIterator> *NewMembers) {
+                             std::vector<NewArchiveMember> *NewMembers) {
   switch (Operation) {
   case Print:
   case DisplayTable:
@@ -703,7 +681,7 @@
 }
 
 static int performOperation(ArchiveOperation Operation,
-                            std::vector<NewArchiveIterator> *NewMembers) {
+                            std::vector<NewArchiveMember> *NewMembers) {
   // Create or open the archive object.
   ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
       MemoryBuffer::getFile(ArchiveName, -1, false);
@@ -741,7 +719,7 @@
   failIfError(Buf.getError());
   const MemoryBuffer &Ref = *Buf.get();
   bool Saved = false;
-  std::vector<NewArchiveIterator> NewMembers;
+  std::vector<NewArchiveMember> NewMembers;
   std::vector<std::unique_ptr<MemoryBuffer>> ArchiveBuffers;
   std::vector<std::unique_ptr<object::Archive>> Archives;
 
@@ -772,10 +750,7 @@
       object::Archive &Lib = *Archives.back();
       for (auto &MemberOrErr : Lib.children()) {
         failIfError(MemberOrErr.getError());
-        auto &Member = MemberOrErr.get();
-        ErrorOr<StringRef> NameOrErr = Member.getName();
-        failIfError(NameOrErr.getError());
-        addMember(NewMembers, Member, *NameOrErr);
+        addMember(NewMembers, *MemberOrErr);
       }
       break;
     }