diff --git a/llvm/include/llvm/Object/Archive.h b/llvm/include/llvm/Object/Archive.h
--- a/llvm/include/llvm/Object/Archive.h
+++ b/llvm/include/llvm/Object/Archive.h
@@ -34,35 +34,59 @@
 
 class Archive;
 
-class ArchiveMemberHeader {
+class AbstractArchiveMemberHeader {
 public:
   friend class Archive;
-
-  ArchiveMemberHeader(Archive const *Parent, const char *RawHeaderPtr,
-                      uint64_t Size, Error *Err);
-  // ArchiveMemberHeader() = default;
-
+  virtual std::unique_ptr<AbstractArchiveMemberHeader> clone() const = 0;
+  virtual ~AbstractArchiveMemberHeader(){};
   /// Get the name without looking up long names.
-  Expected<StringRef> getRawName() const;
+  virtual Expected<StringRef> getRawName() const = 0;
 
   /// Get the name looking up long names.
-  Expected<StringRef> getName(uint64_t Size) const;
+  virtual Expected<StringRef> getName(uint64_t Size) const = 0;
+
+  virtual Expected<uint64_t> getSize() const = 0;
+  virtual uint64_t getOffset() const = 0;
 
-  Expected<uint64_t> getSize() const;
+  virtual StringRef getRawAccessMode() const = 0;
+  virtual StringRef getRawLastModified() const = 0;
+  virtual StringRef getRawUID() const = 0;
+  virtual StringRef getRawGID() const = 0;
 
   Expected<sys::fs::perms> getAccessMode() const;
   Expected<sys::TimePoint<std::chrono::seconds>> getLastModified() const;
 
-  StringRef getRawLastModified() const {
-    return StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
-        .rtrim(' ');
-  }
-
   Expected<unsigned> getUID() const;
   Expected<unsigned> getGID() const;
 
-  // This returns the size of the private struct ArMemHdrType
-  uint64_t getSizeOf() const { return sizeof(ArMemHdrType); }
+  // Returns the size in bytes of the format-defined header of derived class.
+  virtual uint64_t getSizeOf() const { return 0; }
+
+  Archive const *Parent;
+  AbstractArchiveMemberHeader(const Archive *Parent) : Parent(Parent){};
+};
+
+class ArchiveMemberHeader : public AbstractArchiveMemberHeader {
+public:
+  ArchiveMemberHeader(const Archive *Parent, const char *RawHeaderPtr,
+                      uint64_t Size, Error *Err);
+
+  std::unique_ptr<AbstractArchiveMemberHeader> clone() const override {
+    return std::unique_ptr<AbstractArchiveMemberHeader>(
+        new ArchiveMemberHeader(*this));
+  }
+
+  Expected<StringRef> getRawName() const override;
+  Expected<StringRef> getName(uint64_t Size) const override;
+  Expected<uint64_t> getSize() const override;
+
+  uint64_t getOffset() const override;
+  StringRef getRawAccessMode() const override;
+  StringRef getRawLastModified() const override;
+  StringRef getRawUID() const override;
+  StringRef getRawGID() const override;
+
+  uint64_t getSizeOf() const override { return sizeof(ArMemHdrType); }
 
 private:
   struct ArMemHdrType {
@@ -74,7 +98,49 @@
     char Size[10]; ///< Size of data, not including header or padding.
     char Terminator[2];
   };
-  Archive const *Parent;
+  ArMemHdrType const *ArMemHdr;
+};
+
+class BigArchiveMemberHeader : public AbstractArchiveMemberHeader {
+public:
+  BigArchiveMemberHeader(Archive const *Parent, const char *RawHeaderPtr,
+                         uint64_t Size, Error *Err);
+  std::unique_ptr<AbstractArchiveMemberHeader> clone() const override {
+    return std::unique_ptr<AbstractArchiveMemberHeader>(
+        new BigArchiveMemberHeader(*this));
+  }
+
+  Expected<StringRef> getRawName() const override;
+  Expected<StringRef> getName(uint64_t Size) const override;
+  Expected<uint64_t> getSize() const override;
+
+  uint64_t getOffset() const override;
+  StringRef getRawAccessMode() const override;
+  StringRef getRawLastModified() const override;
+  StringRef getRawUID() const override;
+  StringRef getRawGID() const override;
+
+  uint64_t getSizeOf() const override { return sizeof(ArMemHdrType); }
+  Expected<uint64_t> getNextOffset() const;
+  static bool classof(AbstractArchiveMemberHeader const *Header);
+
+private:
+  // File Member Header
+  struct ArMemHdrType {
+    char Size[20];       // File member size in decimal
+    char NextOffset[20]; // Next member offset in decimal
+    char PrevOffset[20]; // Previous member offset in decimal
+    char LastModified[12];
+    char UID[12];
+    char GID[12];
+    char AccessMode[12];
+    char NameLen[4]; // File member name length in decimal
+    union {
+      char Name[2]; // Start of member name
+      char Terminator[2];
+    };
+  };
+
   ArMemHdrType const *ArMemHdr;
 };
 
@@ -84,10 +150,10 @@
 public:
   class Child {
     friend Archive;
-    friend ArchiveMemberHeader;
+    friend AbstractArchiveMemberHeader;
 
     const Archive *Parent;
-    ArchiveMemberHeader Header;
+    std::unique_ptr<AbstractArchiveMemberHeader> Header;
     /// Includes header but not padding byte.
     StringRef Data;
     /// Offset from Data to the start of the file.
@@ -99,6 +165,44 @@
     Child(const Archive *Parent, const char *Start, Error *Err);
     Child(const Archive *Parent, StringRef Data, uint16_t StartOfFile);
 
+    Child(const Child &C)
+       : Parent(C.Parent), Data(C.Data), StartOfFile(C.StartOfFile) {
+      if (C.Header)
+        Header = C.Header->clone();
+    }
+
+    Child(Child &&C) {
+      Parent = std::move(C.Parent);
+      Header = std::move(C.Header);
+      Data = C.Data;
+      StartOfFile = C.StartOfFile;
+    }
+
+    Child &operator=(Child &&C) noexcept {
+      if (&C == this)
+        return *this;
+
+      Parent = std::move(C.Parent);
+      Header = std::move(C.Header);
+      Data = C.Data;
+      StartOfFile = C.StartOfFile;
+
+      return *this;
+    }
+
+    Child &operator=(const Child &C) {
+      if (&C == this)
+        return *this;
+
+      Parent = C.Parent;
+      if (C.Header)
+        Header = C.Header->clone();
+      Data = C.Data;
+      StartOfFile = C.StartOfFile;
+
+      return *this;
+    }
+
     bool operator==(const Child &other) const {
       assert(!Parent || !other.Parent || Parent == other.Parent);
       return Data.begin() == other.Data.begin();
@@ -109,19 +213,21 @@
 
     Expected<StringRef> getName() const;
     Expected<std::string> getFullName() const;
-    Expected<StringRef> getRawName() const { return Header.getRawName(); }
+    Expected<StringRef> getRawName() const { return Header->getRawName(); }
 
     Expected<sys::TimePoint<std::chrono::seconds>> getLastModified() const {
-      return Header.getLastModified();
+      return Header->getLastModified();
     }
 
-    StringRef getRawLastModified() const { return Header.getRawLastModified(); }
+    StringRef getRawLastModified() const {
+      return Header->getRawLastModified();
+    }
 
-    Expected<unsigned> getUID() const { return Header.getUID(); }
-    Expected<unsigned> getGID() const { return Header.getGID(); }
+    Expected<unsigned> getUID() const { return Header->getUID(); }
+    Expected<unsigned> getGID() const { return Header->getGID(); }
 
     Expected<sys::fs::perms> getAccessMode() const {
-      return Header.getAccessMode();
+      return Header->getAccessMode();
     }
 
     /// \return the size of the archive member without the header or padding.
@@ -218,7 +324,7 @@
   /// Size field is 10 decimal digits long
   static const uint64_t MaxMemberSize = 9999999999;
 
-  enum Kind { K_GNU, K_GNU64, K_BSD, K_DARWIN, K_DARWIN64, K_COFF };
+  enum Kind { K_GNU, K_GNU64, K_BSD, K_DARWIN, K_DARWIN64, K_COFF, K_AIXBIG };
 
   Kind kind() const { return (Kind)Format; }
   bool isThin() const { return IsThin; }
@@ -236,7 +342,6 @@
     return make_range(symbol_begin(), symbol_end());
   }
 
-  // Cast methods.
   static bool classof(Binary const *v) { return v->isArchive(); }
 
   // check if a symbol is in the archive
@@ -247,24 +352,51 @@
   StringRef getSymbolTable() const { return SymbolTable; }
   StringRef getStringTable() const { return StringTable; }
   uint32_t getNumberOfSymbols() const;
+  virtual uint64_t getFirstChildOffset() const { return ArchiveMagicLen; }
 
   std::vector<std::unique_ptr<MemoryBuffer>> takeThinBuffers() {
     return std::move(ThinBuffers);
   }
 
+protected:
+  static constexpr int ArchiveMagicLen = 8;
+  void setFirstRegular(const Child &C);
+
 private:
   StringRef SymbolTable;
   StringRef StringTable;
 
   StringRef FirstRegularData;
   uint16_t FirstRegularStartOfFile = -1;
-  void setFirstRegular(const Child &C);
 
   unsigned Format : 3;
   unsigned IsThin : 1;
   mutable std::vector<std::unique_ptr<MemoryBuffer>> ThinBuffers;
 };
 
+class BigArchive : public Archive {
+  /// Fixed-Length Header.
+  struct BigArFixLenHdrType {
+    char Magic[ArchiveMagicLen]; ///< Big archive magic string.
+    char MemOffset[20];          ///< Offset to member table.
+    char GlobSymOffset[20];      ///< Offset to global symbol table.
+    char
+        GlobSym64Offset[20]; ///< Offset global symbol table for 64-bit objects.
+    char FirstMemberOffset[20]; ///< Offset to first archive member.
+    char LastMemberOffset[20];  ///< Offset to last archive member.
+    char FreeOffset[20];     ///< Offset to first mem on free list.
+  };
+
+  const BigArFixLenHdrType *ArFixLenHdr;
+  uint64_t FirstMemberOffset = 0;
+  uint64_t LastMemberOffset = 0;
+
+public:
+  BigArchive(MemoryBufferRef Source, Error &Err);
+  uint64_t getFirstChildOffset() const override { return FirstMemberOffset; }
+  uint64_t getLastChildOffset() const { return LastMemberOffset; }
+};
+
 } // end namespace object
 } // end namespace llvm
 
diff --git a/llvm/lib/BinaryFormat/Magic.cpp b/llvm/lib/BinaryFormat/Magic.cpp
--- a/llvm/lib/BinaryFormat/Magic.cpp
+++ b/llvm/lib/BinaryFormat/Magic.cpp
@@ -88,6 +88,11 @@
     if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n"))
       return file_magic::archive;
     break;
+  case '<':
+    if (startswith(Magic, "<bigaf>\n"))
+      return file_magic::archive;
+    break;
+
   case '\177':
     if (startswith(Magic, "\177ELF") && Magic.size() >= 18) {
       bool Data2MSB = Magic[5] == 2;
diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Object/Binary.h"
 #include "llvm/Object/Error.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
@@ -31,6 +32,7 @@
 #include <cstdint>
 #include <cstring>
 #include <memory>
+#include <stddef.h>
 #include <string>
 #include <system_error>
 
@@ -40,6 +42,7 @@
 
 const char Magic[] = "!<arch>\n";
 const char ThinMagic[] = "!<thin>\n";
+const char BigMagic[] = "<bigaf>\n";
 
 void Archive::anchor() {}
 
@@ -52,12 +55,13 @@
 ArchiveMemberHeader::ArchiveMemberHeader(const Archive *Parent,
                                          const char *RawHeaderPtr,
                                          uint64_t Size, Error *Err)
-    : Parent(Parent),
-      ArMemHdr(reinterpret_cast<const ArMemHdrType *>(RawHeaderPtr)) {
+    : AbstractArchiveMemberHeader(Parent) {
   if (RawHeaderPtr == nullptr)
     return;
   ErrorAsOutParameter ErrAsOutParam(Err);
 
+  ArMemHdr = reinterpret_cast<const ArMemHdrType *>(RawHeaderPtr);
+
   if (Size < sizeof(ArMemHdrType)) {
     if (Err) {
       std::string Msg("remaining size of archive too small for next archive "
@@ -94,6 +98,33 @@
   }
 }
 
+BigArchiveMemberHeader::BigArchiveMemberHeader(const Archive *Parent,
+                                               const char *RawHeaderPtr,
+                                               uint64_t Size, Error *Err)
+    : AbstractArchiveMemberHeader(Parent) {
+  if (RawHeaderPtr == nullptr)
+    return;
+  ErrorAsOutParameter ErrAsOutParam(Err);
+
+  ArMemHdr = reinterpret_cast<const ArMemHdrType *>(RawHeaderPtr);
+
+  if (Size < sizeof(ArMemHdrType)) {
+    if (Err) {
+      std::string Msg("remaining size of archive too small for next archive "
+                      "member header ");
+      Expected<StringRef> NameOrErr = getName(Size);
+      if (!NameOrErr) {
+        consumeError(NameOrErr.takeError());
+        uint64_t Offset = RawHeaderPtr - Parent->getData().data();
+        *Err = malformedError(Msg + "at offset " + Twine(Offset));
+      } else
+        *Err = malformedError(Msg + "for " + NameOrErr.get());
+    }
+    return;
+  }
+
+}
+
 // This gets the raw name from the ArMemHdr->Name field and checks that it is
 // valid for the kind of archive.  If it is not valid it returns an Error.
 Expected<StringRef> ArchiveMemberHeader::getRawName() const {
@@ -121,7 +152,16 @@
   return StringRef(ArMemHdr->Name, end);
 }
 
-// This gets the name looking up long names. Size is the size of the archive
+bool BigArchiveMemberHeader::classof(
+    const AbstractArchiveMemberHeader *Header) {
+  return Header->Parent->kind() == Archive::K_AIXBIG;
+}
+
+Expected<StringRef> BigArchiveMemberHeader::getRawName() const {
+  StringRef::size_type NameSize = strtol(ArMemHdr->NameLen, NULL, 10);
+  return StringRef(ArMemHdr->Name, NameSize);
+}
+
 // member including the header, so the size of any name following the header
 // is checked to make sure it does not overflow.
 Expected<StringRef> ArchiveMemberHeader::getName(uint64_t Size) const {
@@ -224,75 +264,155 @@
   return Name.drop_back(1);
 }
 
+Expected<StringRef> BigArchiveMemberHeader::getName(uint64_t Size) const {
+  // The raw name itself can be invalid.
+  Expected<StringRef> NameOrErr = getRawName();
+  if (!NameOrErr)
+    return NameOrErr.takeError();
+  return NameOrErr.get();
+}
+
 Expected<uint64_t> ArchiveMemberHeader::getSize() const {
-  uint64_t Ret;
-  if (StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size))
-          .rtrim(" ")
-          .getAsInteger(10, Ret)) {
-    std::string Buf;
-    raw_string_ostream OS(Buf);
-    OS.write_escaped(
-        StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size)).rtrim(" "));
-    OS.flush();
+  uint64_t Size;
+  StringRef RawSize =
+      StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size)).rtrim(" ");
+  if (RawSize.getAsInteger(10, Size)) {
     uint64_t Offset =
         reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
     return malformedError("characters in size field in archive header are not "
                           "all decimal numbers: '" +
-                          Buf +
+                          RawSize +
                           "' for archive "
                           "member header at offset " +
                           Twine(Offset));
   }
-  return Ret;
+  return Size;
 }
 
-Expected<sys::fs::perms> ArchiveMemberHeader::getAccessMode() const {
-  unsigned Ret;
-  if (StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
-          .rtrim(' ')
-          .getAsInteger(8, Ret)) {
-    std::string Buf;
-    raw_string_ostream OS(Buf);
-    OS.write_escaped(
-        StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
-            .rtrim(" "));
-    OS.flush();
+Expected<uint64_t> BigArchiveMemberHeader::getSize() const {
+  uint64_t Size;
+  uint64_t NameLen;
+  StringRef RawSize =
+      StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size)).rtrim(" ");
+  if (RawSize.getAsInteger(10, Size)) {
     uint64_t Offset =
         reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in size field in archive header are not "
+                          "all decimal numbers: '" +
+                          RawSize +
+                          "' for archive "
+                          "member header at offset " +
+                          Twine(Offset));
+  }
+
+  StringRef RawNameLen =
+      StringRef(ArMemHdr->NameLen, sizeof(ArMemHdr->NameLen)).rtrim(" ");
+  if (RawNameLen.getAsInteger(10, NameLen)) {
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError(
+        "characters in name length field in archive header are not "
+        "all decimal numbers: '" +
+        RawNameLen +
+        "' for archive "
+        "member header at offset " +
+        Twine(Offset));
+  }
+  return Size + (((NameLen + 1) >> 1) << 1);
+}
+
+Expected<uint64_t> BigArchiveMemberHeader::getNextOffset() const {
+  uint64_t NextOffset;
+  StringRef RawStringRef =
+      StringRef(ArMemHdr->NextOffset, sizeof(ArMemHdr->NextOffset)).rtrim(" ");
+
+  if (RawStringRef.getAsInteger(10, NextOffset)) {
+    uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr->NextOffset) -
+                      Parent->getData().data();
+    return malformedError("characters in size field in archive header are not "
+                          "all decimal numbers: '" +
+                          RawStringRef +
+                          "' for archive "
+                          "member header at offset " +
+                          Twine(Offset));
+  }
+  return NextOffset;
+}
+
+uint64_t ArchiveMemberHeader::getOffset() const {
+  uint64_t Offset =
+      reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+  return Offset;
+}
+
+uint64_t BigArchiveMemberHeader::getOffset() const {
+  uint64_t Offset =
+      reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+  return Offset;
+}
+
+// This gets the raw access mode from the ArMemHdr->AccessMode field.
+StringRef ArchiveMemberHeader::getRawAccessMode() const {
+  return StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
+      .rtrim(' ');
+}
+
+StringRef BigArchiveMemberHeader::getRawAccessMode() const {
+  return StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
+      .rtrim(' ');
+}
+
+Expected<sys::fs::perms> AbstractArchiveMemberHeader::getAccessMode() const {
+  unsigned Ret;
+  if (getRawAccessMode().getAsInteger(8, Ret)) {
+    uint64_t Offset = getOffset();
     return malformedError("characters in AccessMode field in archive header "
                           "are not all decimal numbers: '" +
-                          Buf + "' for the archive member header at offset " +
+                          getRawAccessMode() +
+                          "' for the archive member header at offset " +
                           Twine(Offset));
   }
   return static_cast<sys::fs::perms>(Ret);
 }
 
+// This gets ArMemHdr->LastModified field.
+StringRef ArchiveMemberHeader::getRawLastModified() const {
+  return StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
+      .rtrim(' ');
+}
+
+StringRef BigArchiveMemberHeader::getRawLastModified() const {
+  return StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
+      .rtrim(' ');
+}
+
 Expected<sys::TimePoint<std::chrono::seconds>>
-ArchiveMemberHeader::getLastModified() const {
+AbstractArchiveMemberHeader::getLastModified() const {
   unsigned Seconds;
-  if (StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
-          .rtrim(' ')
-          .getAsInteger(10, Seconds)) {
-    std::string Buf;
-    raw_string_ostream OS(Buf);
-    OS.write_escaped(
-        StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
-            .rtrim(" "));
-    OS.flush();
-    uint64_t Offset =
-        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+  if (getRawLastModified().getAsInteger(10, Seconds)) {
+    uint64_t Offset = getOffset();
     return malformedError("characters in LastModified field in archive header "
                           "are not all decimal numbers: '" +
-                          Buf + "' for the archive member header at offset " +
+                          getRawLastModified() +
+                          "' for the archive member header at offset " +
                           Twine(Offset));
   }
 
   return sys::toTimePoint(Seconds);
 }
 
-Expected<unsigned> ArchiveMemberHeader::getUID() const {
+// This gets the raw UID from the ArMemHdr->UID field.
+StringRef ArchiveMemberHeader::getRawUID() const {
+  return StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
+}
+
+StringRef BigArchiveMemberHeader::getRawUID() const {
+  return StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
+}
+
+Expected<unsigned> AbstractArchiveMemberHeader::getUID() const {
   unsigned Ret;
-  StringRef User = StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
+  StringRef User = getRawUID();
   if (User.empty())
     return 0;
   if (User.getAsInteger(10, Ret)) {
@@ -300,8 +420,7 @@
     raw_string_ostream OS(Buf);
     OS.write_escaped(User);
     OS.flush();
-    uint64_t Offset =
-        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    uint64_t Offset = getOffset();
     return malformedError("characters in UID field in archive header "
                           "are not all decimal numbers: '" +
                           Buf + "' for the archive member header at offset " +
@@ -310,21 +429,25 @@
   return Ret;
 }
 
-Expected<unsigned> ArchiveMemberHeader::getGID() const {
+// This gets the raw GID from the ArMemHdr->GID field.
+StringRef ArchiveMemberHeader::getRawGID() const {
+  return StringRef(ArMemHdr->GID, sizeof(ArMemHdr->GID)).rtrim(' ');
+}
+
+StringRef BigArchiveMemberHeader::getRawGID() const {
+  return StringRef(ArMemHdr->GID, sizeof(ArMemHdr->GID)).rtrim(' ');
+}
+
+Expected<unsigned> AbstractArchiveMemberHeader::getGID() const {
   unsigned Ret;
-  StringRef Group = StringRef(ArMemHdr->GID, sizeof(ArMemHdr->GID)).rtrim(' ');
+  StringRef Group = getRawGID();
   if (Group.empty())
     return 0;
   if (Group.getAsInteger(10, Ret)) {
-    std::string Buf;
-    raw_string_ostream OS(Buf);
-    OS.write_escaped(Group);
-    OS.flush();
-    uint64_t Offset =
-        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    uint64_t Offset = getOffset();
     return malformedError("characters in GID field in archive header "
                           "are not all decimal numbers: '" +
-                          Buf + "' for the archive member header at offset " +
+                          Group + "' for the archive member header at offset " +
                           Twine(Offset));
   }
   return Ret;
@@ -332,18 +455,38 @@
 
 Archive::Child::Child(const Archive *Parent, StringRef Data,
                       uint16_t StartOfFile)
-    : Parent(Parent), Header(Parent, Data.data(), Data.size(), nullptr),
-      Data(Data), StartOfFile(StartOfFile) {}
+    : Parent(Parent), Data(Data), StartOfFile(StartOfFile) {
+  // Create the right concrete archive member as a function of Kind.
+  if (Parent->kind() != K_AIXBIG) {
+    Header = std::make_unique<ArchiveMemberHeader>(
+        ArchiveMemberHeader(Parent, Data.data(), Data.size(), nullptr));
+  } else {
+    Header = std::make_unique<BigArchiveMemberHeader>(
+        BigArchiveMemberHeader(Parent, Data.data(), Data.size(), nullptr));
+  }
+}
 
 Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
-    : Parent(Parent),
-      Header(Parent, Start,
-             Parent
-                 ? Parent->getData().size() - (Start - Parent->getData().data())
-                 : 0,
-             Err) {
-  if (!Start)
+    : Parent(Parent) {
+  if (!Start) {
+    Header = nullptr;
     return;
+  }
+
+  // Create the right concrete archive member as a function of Kind.
+  if (Parent->kind() != K_AIXBIG) {
+    Header = std::make_unique<ArchiveMemberHeader>(ArchiveMemberHeader(
+        Parent, Start,
+        Parent ? Parent->getData().size() - (Start - Parent->getData().data())
+               : 0,
+        Err));
+  } else {
+    Header = std::make_unique<BigArchiveMemberHeader>(BigArchiveMemberHeader(
+        Parent, Start,
+        Parent ? Parent->getData().size() - (Start - Parent->getData().data())
+               : 0,
+        Err));
+  }
 
   // If we are pointed to real data, Start is not a nullptr, then there must be
   // a non-null Err pointer available to report malformed data on.  Only in
@@ -358,7 +501,7 @@
   if (*Err)
     return;
 
-  uint64_t Size = Header.getSizeOf();
+  uint64_t Size = Header->getSizeOf();
   Data = StringRef(Start, Size);
   Expected<bool> isThinOrErr = isThinMember();
   if (!isThinOrErr) {
@@ -377,7 +520,7 @@
   }
 
   // Setup StartOfFile and PaddingBytes.
-  StartOfFile = Header.getSizeOf();
+  StartOfFile = Header->getSizeOf();
   // Don't include attached name.
   Expected<StringRef> NameOrErr = getRawName();
   if (!NameOrErr) {
@@ -385,17 +528,20 @@
     return;
   }
   StringRef Name = NameOrErr.get();
-  if (Name.startswith("#1/")) {
+
+  if (Parent->kind() == Archive::K_AIXBIG) {
+    // Add name to found the real start of child object, the real start is even
+    // alignment.
+    StartOfFile += ((Name.size() + 1) >> 1) << 1;
+  } else if (Name.startswith("#1/")) {
     uint64_t NameSize;
-    if (Name.substr(3).rtrim(' ').getAsInteger(10, NameSize)) {
-      std::string Buf;
-      raw_string_ostream OS(Buf);
-      OS.write_escaped(Name.substr(3).rtrim(' '));
-      OS.flush();
+    StringRef RawNameSize = Name.substr(3).rtrim(' ');
+    if (RawNameSize.getAsInteger(10, NameSize)) {
       uint64_t Offset = Start - Parent->getData().data();
       *Err = malformedError("long name length characters after the #1/ are "
                             "not all decimal numbers: '" +
-                            Buf + "' for archive member header at offset " +
+                            RawNameSize +
+                            "' for archive member header at offset " +
                             Twine(Offset));
       return;
     }
@@ -405,16 +551,16 @@
 
 Expected<uint64_t> Archive::Child::getSize() const {
   if (Parent->IsThin)
-    return Header.getSize();
+    return Header->getSize();
   return Data.size() - StartOfFile;
 }
 
 Expected<uint64_t> Archive::Child::getRawSize() const {
-  return Header.getSize();
+  return Header->getSize();
 }
 
 Expected<bool> Archive::Child::isThinMember() const {
-  Expected<StringRef> NameOrErr = Header.getRawName();
+  Expected<StringRef> NameOrErr = Header->getRawName();
   if (!NameOrErr)
     return NameOrErr.takeError();
   StringRef Name = NameOrErr.get();
@@ -462,16 +608,35 @@
 }
 
 Expected<Archive::Child> Archive::Child::getNext() const {
-  size_t SpaceToSkip = Data.size();
-  // If it's odd, add 1 to make it even.
-  if (SpaceToSkip & 1)
-    ++SpaceToSkip;
 
-  const char *NextLoc = Data.data() + SpaceToSkip;
+  const char *NextLoc = nullptr;
+
+  if (Parent->kind() != K_AIXBIG) {
+    size_t SpaceToSkip = Data.size();
+    // If it's odd, add 1 to make it even.
+    if (SpaceToSkip & 1)
+      ++SpaceToSkip;
+
+    NextLoc = Data.data() + SpaceToSkip;
 
-  // Check to see if this is at the end of the archive.
-  if (NextLoc == Parent->Data.getBufferEnd())
-    return Child(nullptr, nullptr, nullptr);
+    // Check to see if this is at the end of the archive.
+    if (NextLoc == Parent->Data.getBufferEnd())
+      return Child(nullptr, nullptr, nullptr);
+  } else {
+    // If current child offset is equal to the last ar offset, current child is
+    // the last one.
+    if (Header->getOffset() ==
+        static_cast<const BigArchive *>(Parent)->getLastChildOffset())
+      return Child(nullptr, nullptr, nullptr);
+    else {
+      Expected<uint64_t> NextOffSetOrErr =
+          dyn_cast<BigArchiveMemberHeader>(Header.get())->getNextOffset();
+      if (NextOffSetOrErr)
+        NextLoc = Parent->getData().data() + NextOffSetOrErr.get();
+      else
+        return NextOffSetOrErr.takeError();
+    }
+  }
 
   // Check to see if this is past the end of the archive.
   if (NextLoc > Parent->Data.getBufferEnd()) {
@@ -505,7 +670,8 @@
   if (!RawSizeOrErr)
     return RawSizeOrErr.takeError();
   uint64_t RawSize = RawSizeOrErr.get();
-  Expected<StringRef> NameOrErr = Header.getName(Header.getSizeOf() + RawSize);
+  Expected<StringRef> NameOrErr =
+      Header->getName(Header->getSizeOf() + RawSize);
   if (!NameOrErr)
     return NameOrErr.takeError();
   StringRef Name = NameOrErr.get();
@@ -537,10 +703,19 @@
 
 Expected<std::unique_ptr<Archive>> Archive::create(MemoryBufferRef Source) {
   Error Err = Error::success();
-  std::unique_ptr<Archive> Ret(new Archive(Source, Err));
+
+  Archive *Ret;
+
+  StringRef Buffer = Source.getBuffer();
+
+  if (Buffer.startswith(BigMagic))
+    Ret = new BigArchive(Source, Err);
+  else
+    Ret = new Archive(Source, Err);
+
   if (Err)
     return std::move(Err);
-  return std::move(Ret);
+  return std::unique_ptr<Archive>(Ret);
 }
 
 void Archive::setFirstRegular(const Child &C) {
@@ -557,6 +732,10 @@
     IsThin = true;
   } else if (Buffer.startswith(Magic)) {
     IsThin = false;
+  } else if (Buffer.startswith(BigMagic)) {
+    Format = K_AIXBIG;
+    IsThin = false;
+    return;
   } else {
     Err = make_error<GenericBinaryError>("file too small to be an archive",
                                          object_error::invalid_file_type);
@@ -564,10 +743,10 @@
   }
 
   // Make sure Format is initialized before any call to
-  // ArchiveMemberHeader::getName() is made.  This could be a valid empty
-  // archive which is the same in all formats.  So claiming it to be gnu to is
-  // fine if not totally correct before we look for a string table or table of
-  // contents.
+  // ArchiveMemberHeader::getName() is made. Read Magic to deal with AIX Big
+  // Archive. Else, this could be a valid empty archive which is the same in all
+  // formats. So claiming it to be gnu to is fine if not totally correct before
+  // we look for a string table or table of contents.
   Format = K_GNU;
 
   // Get the special members.
@@ -788,7 +967,7 @@
     return child_iterator::itr(
         Child(this, FirstRegularData, FirstRegularStartOfFile), Err);
 
-  const char *Loc = Data.getBufferStart() + strlen(Magic);
+  const char *Loc = Data.getBufferStart() + getFirstChildOffset();
   Child C(this, Loc, &Err);
   if (Err)
     return child_end();
@@ -997,6 +1176,46 @@
 }
 
 // Returns true if archive file contains no member file.
-bool Archive::isEmpty() const { return Data.getBufferSize() == 8; }
+bool Archive::isEmpty() const {
+  return Data.getBufferSize() == ArchiveMagicLen;
+}
 
 bool Archive::hasSymbolTable() const { return !SymbolTable.empty(); }
+
+BigArchive::BigArchive(MemoryBufferRef Source, Error &Err)
+    : Archive(Source, Err) {
+  ErrorAsOutParameter ErrAsOutParam(&Err);
+  StringRef Buffer = Data.getBuffer();
+  ArFixLenHdr = reinterpret_cast<const BigArFixLenHdrType *>(Buffer.data());
+
+  StringRef RawStringRef = StringRef(ArFixLenHdr->FirstMemberOffset,
+                                     sizeof(ArFixLenHdr->FirstMemberOffset))
+                               .rtrim(' ');
+
+  if (RawStringRef.rtrim(' ').getAsInteger(10, FirstMemberOffset)) {
+    Err = malformedError("malformed aix big archive: first member offset \"" +
+                         RawStringRef + "\" is not a number");
+  }
+
+  RawStringRef = StringRef(ArFixLenHdr->LastMemberOffset,
+                           sizeof(ArFixLenHdr->LastMemberOffset))
+                     .rtrim(' ');
+
+  if (RawStringRef.getAsInteger(10, LastMemberOffset)) {
+    Err = malformedError("malformed aix big archive: last member offset \"" +
+                         RawStringRef + "\" is not a number");
+  }
+
+  child_iterator I = child_begin(Err, false);
+  if (Err)
+    return;
+  child_iterator E = child_end();
+  if (I == E) {
+    Err = Error::success();
+    return;
+  }
+  const Child *C = &*I;
+  setFirstRegular(*C);
+  Err = Error::success();
+  return;
+}
diff --git a/llvm/lib/Object/ArchiveWriter.cpp b/llvm/lib/Object/ArchiveWriter.cpp
--- a/llvm/lib/Object/ArchiveWriter.cpp
+++ b/llvm/lib/Object/ArchiveWriter.cpp
@@ -137,6 +137,7 @@
   case object::Archive::K_DARWIN:
   case object::Archive::K_DARWIN64:
     return true;
+  case object::Archive::K_AIXBIG:
   case object::Archive::K_COFF:
     break;
   }
@@ -199,6 +200,7 @@
   case object::Archive::K_BSD:
   case object::Archive::K_DARWIN:
   case object::Archive::K_COFF:
+  case object::Archive::K_AIXBIG:
     return false;
   case object::Archive::K_DARWIN64:
   case object::Archive::K_GNU64:
diff --git a/llvm/test/Object/Inputs/aix-big-archive-member.o b/llvm/test/Object/Inputs/aix-big-archive-member.o
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/llvm/test/Object/Inputs/aix-big-archive.a b/llvm/test/Object/Inputs/aix-big-archive.a
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/llvm/test/Object/archive-big-extract.test b/llvm/test/Object/archive-big-extract.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/Object/archive-big-extract.test
@@ -0,0 +1,4 @@
+## Test extract xcoff object file from AIX big archive.
+# RUN: rm -rf %t && mkdir -p %t/extracted/
+# RUN:  cd %t/extracted/  &&  llvm-ar x %p/Inputs/aix-big-archive.a
+# RUN: diff %t/extracted/empty.o %p/Inputs/aix-big-archive-member.o
diff --git a/llvm/test/Object/archive-big-print.test b/llvm/test/Object/archive-big-print.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/Object/archive-big-print.test
@@ -0,0 +1,3 @@
+## Test printing an archive created by AIX ar (Big Archive).
+RUN: llvm-ar p %p/Inputs/aix-big-archive.a evenlen | FileCheck %s --check-prefix=AIXBIG --implicit-check-not={{.}}
+AIXBIG: content_of_evenlen
diff --git a/llvm/test/Object/archive-big-read.test b/llvm/test/Object/archive-big-read.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/Object/archive-big-read.test
@@ -0,0 +1,5 @@
+## Test reading an archive created by AIX ar (Big Archive).
+RUN: env TZ=GMT llvm-ar tv %p/Inputs/aix-big-archive.a | FileCheck %s --strict-whitespace --check-prefix=AIXBIG --implicit-check-not={{.}}
+AIXBIG:      rw-r--r-- 0/0     19 Jan  1 00:00 1970 evenlen
+AIXBIG-NEXT: rw-r--r-- 0/0      7 Jan  1 00:00 1970 oddlen
+AIXBIG-NEXT: rw-r--r-- 0/0    258 Jan  1 00:00 1970 empty.o
diff --git a/llvm/test/tools/llvm-objdump/XCOFF/Inputs/big-archive-libtest.a b/llvm/test/tools/llvm-objdump/XCOFF/Inputs/big-archive-libtest.a
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/llvm/test/tools/llvm-objdump/XCOFF/archive-headers.test b/llvm/test/tools/llvm-objdump/XCOFF/archive-headers.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/XCOFF/archive-headers.test
@@ -0,0 +1,8 @@
+;; Test llvm-objdump supporting the decode the archive header for xcoff.
+; RUN: llvm-objdump %p/Inputs/big-archive-libtest.a --archive-headers  | FileCheck %s
+
+; CHECK:       {{.*}}big-archive-libtest.a(test_xlclang++.o):    file format aixcoff-rs6000
+; CHECK-NEXT: rw------- 550591/1000499   3154 Tue Oct  5 10:37:23 2021 test_xlclang++.o
+
+; CHECK:       {{.*}}big-archive-libtest.a(test1_gcc.o): file format aixcoff-rs6000
+; CHECK-NEXT: rw------- 550591/1000499   1596 Tue Oct  5 11:11:06 2021 test1_gcc.o
diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -1003,12 +1003,17 @@
     fail("unable to open '" + ArchiveName + "': " + EC.message());
 
   if (!EC) {
-    Error Err = Error::success();
-    object::Archive Archive(Buf.get()->getMemBufferRef(), Err);
-    failIfError(std::move(Err), "unable to load '" + ArchiveName + "'");
-    if (Archive.isThin())
+    Expected<std::unique_ptr<object::Archive>> ArchiveOrError =
+        object::Archive::create(Buf.get()->getMemBufferRef());
+    if (!ArchiveOrError)
+      failIfError(ArchiveOrError.takeError(),
+                  "unable to load '" + ArchiveName + "'");
+
+    std::unique_ptr<object::Archive> Archive = std::move(ArchiveOrError.get());
+
+    if (Archive->isThin())
       CompareFullPath = true;
-    performOperation(Operation, &Archive, std::move(Buf.get()), NewMembers);
+    performOperation(Operation, Archive.get(), std::move(Buf.get()), NewMembers);
     return 0;
   }