Index: include/llvm/Object/COFF.h
===================================================================
--- include/llvm/Object/COFF.h
+++ include/llvm/Object/COFF.h
@@ -14,9 +14,11 @@
 #ifndef LLVM_OBJECT_COFF_H
 #define LLVM_OBJECT_COFF_H
 
+#include "llvm/ADT/PointerUnion.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/Endian.h"
+#include "llvm/Support/ErrorOr.h"
 
 namespace llvm {
 template <typename T> class ArrayRef;
@@ -62,6 +64,22 @@
   bool isImportLibrary() const { return NumberOfSections == 0xffff; }
 };
 
+struct coff_bigobj_file_header {
+  support::ulittle16_t Sig1;
+  support::ulittle16_t Sig2;
+  support::ulittle16_t Version;
+  support::ulittle16_t Machine;
+  support::ulittle32_t TimeDateStamp;
+  support::ulittle8_t  UUID[16];
+  support::ulittle32_t unused1;
+  support::ulittle32_t unused2;
+  support::ulittle32_t unused3;
+  support::ulittle32_t unused4;
+  support::ulittle32_t NumberOfSections;
+  support::ulittle32_t PointerToSymbolTable;
+  support::ulittle32_t NumberOfSymbols;
+};
+
 /// The 32-bit PE header that follows the COFF header.
 struct pe32_header {
   support::ulittle16_t Magic;
@@ -180,67 +198,115 @@
 typedef support::ulittle32_t export_name_pointer_table_entry;
 typedef support::ulittle16_t export_ordinal_table_entry;
 
-struct coff_symbol {
-  struct StringTableOffset {
-    support::ulittle32_t Zeroes;
-    support::ulittle32_t Offset;
-  };
+struct StringTableOffset {
+  support::ulittle32_t Zeroes;
+  support::ulittle32_t Offset;
+};
 
+template <typename SectionNumberType>
+struct coff_symbol {
   union {
-    char ShortName[8];
+    char ShortName[COFF::NameSize];
     StringTableOffset Offset;
   } Name;
 
   support::ulittle32_t Value;
-  support::ulittle16_t SectionNumber;
+  SectionNumberType SectionNumber;
 
   support::ulittle16_t Type;
 
   support::ulittle8_t StorageClass;
   support::ulittle8_t NumberOfAuxSymbols;
+};
+
+typedef coff_symbol<support::ulittle16_t> coff_symbol16;
+typedef coff_symbol<support::ulittle32_t> coff_symbol32;
+
+class COFFSymbolRef {
+public:
+  COFFSymbolRef(const coff_symbol16 *CS) : CS16(CS), CS32(nullptr) {}
+  COFFSymbolRef(const coff_symbol32 *CS) : CS16(nullptr), CS32(CS) {}
+
+  const void *getRawPtr() const {
+    return CS16 ? static_cast<const void *>(CS16) : CS32;
+  }
+
+  const char *getShortName() const {
+    return CS16 ? CS16->Name.ShortName : CS32->Name.ShortName;
+  }
+
+  const StringTableOffset &getStringTableOffset() const {
+    return CS16 ? CS16->Name.Offset : CS32->Name.Offset;
+  }
+
+  uint32_t getValue() const { return CS16 ? CS16->Value : CS32->Value; }
+
+  int32_t getSectionNumber() const {
+    if (CS16) {
+      if (CS16->SectionNumber <= COFF::MaxNumberOfSections16)
+        return CS16->SectionNumber;
+      return static_cast<int16_t>(CS16->SectionNumber);
+    }
+    return static_cast<int32_t>(CS32->SectionNumber);
+  }
 
-  uint8_t getBaseType() const { return Type & 0x0F; }
+  uint16_t getType() const { return CS16 ? CS16->Type : CS32->Type; }
 
-  uint8_t getComplexType() const { return (Type & 0xF0) >> 4; }
+  uint8_t getStorageClass() const {
+    return CS16 ? CS16->StorageClass : CS32->StorageClass;
+  }
+
+  uint8_t getNumberOfAuxSymbols() const {
+    return CS16 ? CS16->NumberOfAuxSymbols : CS32->NumberOfAuxSymbols;
+  }
+
+  uint8_t getBaseType() const { return getType() & 0x0F; }
+
+  uint8_t getComplexType() const { return (getType() & 0xF0) >> 4; }
 
   bool isFunctionDefinition() const {
-    return StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
+    return getStorageClass() == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
            getBaseType() == COFF::IMAGE_SYM_TYPE_NULL &&
            getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION &&
-           !COFF::isReservedSectionNumber(SectionNumber);
+           getSectionNumber() > 0;
   }
 
   bool isFunctionLineInfo() const {
-    return StorageClass == COFF::IMAGE_SYM_CLASS_FUNCTION;
+    return getStorageClass() == COFF::IMAGE_SYM_CLASS_FUNCTION;
   }
 
   bool isWeakExternal() const {
-    return StorageClass == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL ||
-           (StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
-            SectionNumber == COFF::IMAGE_SYM_UNDEFINED && Value == 0);
+    return getStorageClass() == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL ||
+           (getStorageClass() == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
+            getSectionNumber() == COFF::IMAGE_SYM_UNDEFINED && getValue() == 0);
   }
 
   bool isFileRecord() const {
-    return StorageClass == COFF::IMAGE_SYM_CLASS_FILE;
+    return getStorageClass() == COFF::IMAGE_SYM_CLASS_FILE;
   }
 
   bool isSectionDefinition() const {
     // C++/CLI creates external ABS symbols for non-const appdomain globals.
     // These are also followed by an auxiliary section definition.
-    bool isAppdomainGlobal = StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
-                             SectionNumber == COFF::IMAGE_SYM_ABSOLUTE;
+    bool isAppdomainGlobal =
+        getStorageClass() == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
+        getSectionNumber() == COFF::IMAGE_SYM_ABSOLUTE;
     bool isOrdinarySection =
-        StorageClass == COFF::IMAGE_SYM_CLASS_STATIC && Value == 0;
+        getStorageClass() == COFF::IMAGE_SYM_CLASS_STATIC && getValue() == 0;
     return isAppdomainGlobal || isOrdinarySection;
   }
 
   bool isCLRToken() const {
-    return StorageClass == COFF::IMAGE_SYM_CLASS_CLR_TOKEN;
+    return getStorageClass() == COFF::IMAGE_SYM_CLASS_CLR_TOKEN;
   }
+
+private:
+  const coff_symbol16 *CS16;
+  const coff_symbol32 *CS32;
 };
 
 struct coff_section {
-  char Name[8];
+  char Name[COFF::NameSize];
   support::ulittle32_t VirtualSize;
   support::ulittle32_t VirtualAddress;
   support::ulittle32_t SizeOfRawData;
@@ -270,7 +336,6 @@
   support::ulittle32_t TotalSize;
   support::ulittle32_t PointerToLinenumber;
   support::ulittle32_t PointerToNextFunction;
-  char Unused[2];
 };
 
 struct coff_aux_bf_and_ef_symbol {
@@ -278,17 +343,11 @@
   support::ulittle16_t Linenumber;
   char Unused2[6];
   support::ulittle32_t PointerToNextFunction;
-  char Unused3[2];
 };
 
 struct coff_aux_weak_external {
   support::ulittle32_t TagIndex;
   support::ulittle32_t Characteristics;
-  char Unused[10];
-};
-
-struct coff_aux_file {
-  char FileName[18];
 };
 
 struct coff_aux_section_definition {
@@ -298,14 +357,12 @@
   support::ulittle32_t CheckSum;
   support::ulittle16_t Number;
   support::ulittle8_t Selection;
-  char Unused[3];
 };
 
 struct coff_aux_clr_token {
   support::ulittle8_t AuxType;
   support::ulittle8_t Reserved;
   support::ulittle32_t SymbolTableIndex;
-  char Unused[12];
 };
 
 struct coff_load_configuration32 {
@@ -324,7 +381,7 @@
   support::ulittle32_t ProcessAffinityMask;
   support::ulittle32_t ProcessHeapFlags;
   support::ulittle16_t CSDVersion;
-  uint16_t Reserved;
+  support::ulittle16_t Reserved;
   support::ulittle32_t EditList;
   support::ulittle32_t SecurityCookie;
   support::ulittle32_t SEHandlerTable;
@@ -342,11 +399,13 @@
   friend class ImportDirectoryEntryRef;
   friend class ExportDirectoryEntryRef;
   const coff_file_header *COFFHeader;
+  const coff_bigobj_file_header *COFFBigObjHeader;
   const pe32_header *PE32Header;
   const pe32plus_header *PE32PlusHeader;
   const data_directory *DataDirectory;
   const coff_section *SectionTable;
-  const coff_symbol *SymbolTable;
+  const coff_symbol16 *SymbolTable16;
+  const coff_symbol32 *SymbolTable32;
   const char *StringTable;
   uint32_t StringTableSize;
   const import_directory_table_entry *ImportDirectory;
@@ -355,7 +414,8 @@
 
   std::error_code getString(uint32_t offset, StringRef &Res) const;
 
-  const coff_symbol *toSymb(DataRefImpl Symb) const;
+  template <typename coff_symbol_type>
+  const coff_symbol_type *toSymb(DataRefImpl Symb) const;
   const coff_section *toSec(DataRefImpl Sec) const;
   const coff_relocation *toRel(DataRefImpl Rel) const;
 
@@ -363,6 +423,73 @@
   std::error_code initImportTablePtr();
   std::error_code initExportTablePtr();
 
+public:
+  bool isReservedSectionNumber(int32_t SectionNumber) const {
+    if (SymbolTable16)
+      return COFF::isReservedSectionNumber16(SectionNumber);
+    if (SymbolTable32)
+      return COFF::isReservedSectionNumber32(SectionNumber);
+    llvm_unreachable("no symbol table pointer!");
+  }
+  uintptr_t getSymbolTable() const {
+    if (SymbolTable16)
+      return reinterpret_cast<uintptr_t>(SymbolTable16);
+    if (SymbolTable32)
+      return reinterpret_cast<uintptr_t>(SymbolTable32);
+    llvm_unreachable("no symbol table pointer!");
+  }
+  uint16_t getMachine() const {
+    if (COFFHeader)
+      return COFFHeader->Machine;
+    if (COFFBigObjHeader)
+      return COFFBigObjHeader->Machine;
+    llvm_unreachable("no COFF header!");
+  }
+  uint16_t getSizeOfOptionalHeader() const {
+    if (COFFHeader)
+      return COFFHeader->SizeOfOptionalHeader;
+    // bigobj doesn't have this field.
+    if (COFFBigObjHeader)
+      return 0;
+    llvm_unreachable("no COFF header!");
+  }
+  uint16_t getCharacteristics() const {
+    if (COFFHeader)
+      return COFFHeader->Characteristics;
+    // bigobj doesn't have characteristics to speak of,
+    // editbin will silently lie to you if you attempt to set any.
+    if (COFFBigObjHeader)
+      return 0;
+    llvm_unreachable("no COFF header!");
+  }
+  uint32_t getTimeDateStamp() const {
+    if (COFFHeader)
+      return COFFHeader->TimeDateStamp;
+    if (COFFBigObjHeader)
+      return COFFBigObjHeader->TimeDateStamp;
+    llvm_unreachable("no COFF header!");
+  }
+  uint32_t getNumberOfSections() const {
+    if (COFFHeader)
+      return COFFHeader->NumberOfSections;
+    if (COFFBigObjHeader)
+      return COFFBigObjHeader->NumberOfSections;
+    llvm_unreachable("no COFF header!");
+  }
+  uint32_t getPointerToSymbolTable() const {
+    if (COFFHeader)
+      return COFFHeader->PointerToSymbolTable;
+    if (COFFBigObjHeader)
+      return COFFBigObjHeader->PointerToSymbolTable;
+    llvm_unreachable("no COFF header!");
+  }
+  uint32_t getNumberOfSymbols() const {
+    if (COFFHeader)
+      return COFFHeader->NumberOfSymbols;
+    if (COFFBigObjHeader)
+      return COFFBigObjHeader->NumberOfSymbols;
+    llvm_unreachable("no COFF header!");
+  }
 protected:
   void moveSymbolNext(DataRefImpl &Symb) const override;
   std::error_code getSymbolName(DataRefImpl Symb,
@@ -422,7 +549,8 @@
   section_iterator section_end() const override;
 
   const coff_section *getCOFFSection(const SectionRef &Section) const;
-  const coff_symbol *getCOFFSymbol(const SymbolRef &Symbol) const;
+  COFFSymbolRef getCOFFSymbol(const DataRefImpl &Ref) const;
+  COFFSymbolRef getCOFFSymbol(const SymbolRef &Symbol) const;
   const coff_relocation *getCOFFRelocation(const RelocationRef &Reloc) const;
 
   uint8_t getBytesInAddress() const override;
@@ -441,17 +569,42 @@
   std::error_code getDataDirectory(uint32_t index,
                                    const data_directory *&Res) const;
   std::error_code getSection(int32_t index, const coff_section *&Res) const;
-  std::error_code getSymbol(uint32_t index, const coff_symbol *&Res) const;
+  template <typename coff_symbol_type>
+  std::error_code getSymbol(uint32_t index, const coff_symbol_type *&Res) const;
+  ErrorOr<COFFSymbolRef> getSymbol(uint32_t index) const {
+    if (SymbolTable16) {
+      const coff_symbol16 *Symb = nullptr;
+      if (std::error_code EC = getSymbol(index, Symb))
+        return EC;
+      return COFFSymbolRef(Symb);
+    }
+    if (SymbolTable32) {
+      const coff_symbol32 *Symb = nullptr;
+      if (std::error_code EC = getSymbol(index, Symb))
+        return EC;
+      return COFFSymbolRef(Symb);
+    }
+    llvm_unreachable("no symbol table pointer!");
+  }
   template <typename T>
   std::error_code getAuxSymbol(uint32_t index, const T *&Res) const {
-    const coff_symbol *s;
-    std::error_code ec = getSymbol(index, s);
-    Res = reinterpret_cast<const T *>(s);
-    return ec;
+    ErrorOr<COFFSymbolRef> s = getSymbol(index);
+    if (std::error_code EC = s.getError())
+      return EC;
+    Res = reinterpret_cast<const T *>(s->getRawPtr());
+    return object_error::success;
+  }
+  std::error_code getSymbolName(COFFSymbolRef Symbol, StringRef &Res) const;
+
+  ArrayRef<uint8_t> getSymbolAuxData(COFFSymbolRef Symbol) const;
+
+  size_t getSymbolTableEntrySize() const {
+    if (COFFHeader)
+      return sizeof(coff_symbol16);
+    if (COFFBigObjHeader)
+      return sizeof(coff_symbol32);
+    llvm_unreachable("null symbol table pointer!");
   }
-  std::error_code getSymbolName(const coff_symbol *symbol,
-                                StringRef &Res) const;
-  ArrayRef<uint8_t> getSymbolAuxData(const coff_symbol *symbol) const;
 
   std::error_code getSectionName(const coff_section *Sec, StringRef &Res) const;
   std::error_code getSectionContents(const coff_section *Sec,
Index: include/llvm/Support/COFF.h
===================================================================
--- include/llvm/Support/COFF.h
+++ include/llvm/Support/COFF.h
@@ -31,11 +31,16 @@
 namespace COFF {
 
   // The maximum number of sections that a COFF object can have (inclusive).
-  const int MaxNumberOfSections = 65299;
+  const uint16_t MaxNumberOfSections16 = 65299;
 
   // The PE signature bytes that follows the DOS stub header.
   static const char PEMagic[] = { 'P', 'E', '\0', '\0' };
 
+  static const char BigObjMagic[] = {
+      '\xc7', '\xa1', '\xba', '\xd1', '\xee', '\xba', '\xa9', '\x4b',
+      '\xaf', '\x20', '\xfa', '\xf6', '\x6a', '\xa4', '\xdc', '\xb8',
+  };
+
   // Sizes in bytes of various things in the COFF format.
   enum {
     HeaderSize     = 20,
@@ -55,6 +60,24 @@
     uint16_t Characteristics;
   };
 
+  struct BigObjHeader {
+    enum { MinBigObjectVersion = 2 };
+
+    uint16_t Sig1; ///< Must be IMAGE_FILE_MACHINE_UNKNOWN (0).
+    uint16_t Sig2; ///< Must be 0xFFFF.
+    uint16_t Version;
+    uint16_t Machine;
+    uint32_t TimeDateStamp;
+    uint8_t  UUID[16];
+    uint32_t unused1;
+    uint32_t unused2;
+    uint32_t unused3;
+    uint32_t unused4;
+    uint32_t NumberOfSections;
+    uint32_t PointerToSymbolTable;
+    uint32_t NumberOfSymbols;
+  };
+
   enum MachineTypes {
     MT_Invalid = 0xffff,
 
@@ -140,9 +163,9 @@
     SF_WeakExternal = 0x01000000
   };
 
-  enum SymbolSectionNumber {
-    IMAGE_SYM_DEBUG     = 0xFFFE,
-    IMAGE_SYM_ABSOLUTE  = 0xFFFF,
+  enum SymbolSectionNumber : int32_t {
+    IMAGE_SYM_DEBUG     = -2,
+    IMAGE_SYM_ABSOLUTE  = -1,
     IMAGE_SYM_UNDEFINED = 0
   };
 
@@ -647,10 +670,12 @@
     DEBUG_INDEX_SUBSECTION        = 0xF4
   };
 
-  inline bool isReservedSectionNumber(int N) {
-    return N == IMAGE_SYM_UNDEFINED || N > MaxNumberOfSections;
+  inline bool isReservedSectionNumber16(unsigned short N) {
+    return N == IMAGE_SYM_UNDEFINED || N > MaxNumberOfSections16;
   }
 
+  inline bool isReservedSectionNumber32(int32_t N) { return N <= 0; }
+
 } // End namespace COFF.
 } // End namespace llvm.
 
Index: lib/MC/WinCOFFObjectWriter.cpp
===================================================================
--- lib/MC/WinCOFFObjectWriter.cpp
+++ lib/MC/WinCOFFObjectWriter.cpp
@@ -849,7 +849,7 @@
     MakeSectionReal(*Section, Number);
   }
 
-  if (NumberOfSections > static_cast<size_t>(COFF::MaxNumberOfSections))
+  if (NumberOfSections > static_cast<size_t>(COFF::MaxNumberOfSections16))
     report_fatal_error(
         "PE COFF object files can't have more than 65,299 sections");
 
Index: lib/Object/COFFObjectFile.cpp
===================================================================
--- lib/Object/COFFObjectFile.cpp
+++ lib/Object/COFFObjectFile.cpp
@@ -88,20 +88,22 @@
   return false;
 }
 
-const coff_symbol *COFFObjectFile::toSymb(DataRefImpl Ref) const {
-  const coff_symbol *Addr = reinterpret_cast<const coff_symbol*>(Ref.p);
+template <typename coff_symbol_type>
+const coff_symbol_type *COFFObjectFile::toSymb(DataRefImpl Ref) const {
+  const coff_symbol_type *Addr =
+      reinterpret_cast<const coff_symbol_type *>(Ref.p);
 
-# ifndef NDEBUG
+#ifndef NDEBUG
   // Verify that the symbol points to a valid entry in the symbol table.
   uintptr_t Offset = uintptr_t(Addr) - uintptr_t(base());
-  if (Offset < COFFHeader->PointerToSymbolTable
-      || Offset >= COFFHeader->PointerToSymbolTable
-         + (COFFHeader->NumberOfSymbols * sizeof(coff_symbol)))
+  if (Offset < getPointerToSymbolTable() ||
+      Offset >= getPointerToSymbolTable() +
+                    (getNumberOfSymbols() * sizeof(coff_symbol_type)))
     report_fatal_error("Symbol was outside of symbol table.");
 
-  assert((Offset - COFFHeader->PointerToSymbolTable) % sizeof(coff_symbol)
-         == 0 && "Symbol did not point to the beginning of a symbol");
-# endif
+  assert((Offset - getPointerToSymbolTable()) % sizeof(coff_symbol_type) == 0 &&
+         "Symbol did not point to the beginning of a symbol");
+#endif
 
   return Addr;
 }
@@ -111,8 +113,7 @@
 
 # ifndef NDEBUG
   // Verify that the section points to a valid entry in the section table.
-  if (Addr < SectionTable
-      || Addr >= (SectionTable + COFFHeader->NumberOfSections))
+  if (Addr < SectionTable || Addr >= (SectionTable + getNumberOfSections()))
     report_fatal_error("Section was outside of section table.");
 
   uintptr_t Offset = uintptr_t(Addr) - uintptr_t(SectionTable);
@@ -124,49 +125,58 @@
 }
 
 void COFFObjectFile::moveSymbolNext(DataRefImpl &Ref) const {
-  const coff_symbol *Symb = toSymb(Ref);
-  Symb += 1 + Symb->NumberOfAuxSymbols;
-  Ref.p = reinterpret_cast<uintptr_t>(Symb);
+  if (SymbolTable16) {
+    const coff_symbol16 *Symb = toSymb<coff_symbol16>(Ref);
+    Symb += 1 + Symb->NumberOfAuxSymbols;
+    Ref.p = reinterpret_cast<uintptr_t>(Symb);
+  } else if (SymbolTable32) {
+    const coff_symbol32 *Symb = toSymb<coff_symbol32>(Ref);
+    Symb += 1 + Symb->NumberOfAuxSymbols;
+    Ref.p = reinterpret_cast<uintptr_t>(Symb);
+  } else {
+    llvm_unreachable("no symbol table pointer!");
+  }
 }
 
 std::error_code COFFObjectFile::getSymbolName(DataRefImpl Ref,
                                               StringRef &Result) const {
-  const coff_symbol *Symb = toSymb(Ref);
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
   return getSymbolName(Symb, Result);
 }
 
 std::error_code COFFObjectFile::getSymbolAddress(DataRefImpl Ref,
                                                  uint64_t &Result) const {
-  const coff_symbol *Symb = toSymb(Ref);
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
   const coff_section *Section = nullptr;
-  if (std::error_code EC = getSection(Symb->SectionNumber, Section))
+  if (std::error_code EC = getSection(Symb.getSectionNumber(), Section))
     return EC;
 
-  if (Symb->SectionNumber == COFF::IMAGE_SYM_UNDEFINED)
+  if (Symb.getSectionNumber() == COFF::IMAGE_SYM_UNDEFINED)
     Result = UnknownAddressOrSize;
   else if (Section)
-    Result = Section->VirtualAddress + Symb->Value;
+    Result = Section->VirtualAddress + Symb.getValue();
   else
-    Result = Symb->Value;
+    Result = Symb.getValue();
   return object_error::success;
 }
 
 std::error_code COFFObjectFile::getSymbolType(DataRefImpl Ref,
                                               SymbolRef::Type &Result) const {
-  const coff_symbol *Symb = toSymb(Ref);
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
   Result = SymbolRef::ST_Other;
-  if (Symb->StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
-      Symb->SectionNumber == COFF::IMAGE_SYM_UNDEFINED) {
+
+  if (Symb.getStorageClass() == COFF::IMAGE_SYM_CLASS_EXTERNAL &&
+      Symb.getSectionNumber() == COFF::IMAGE_SYM_UNDEFINED) {
     Result = SymbolRef::ST_Unknown;
-  } else if (Symb->isFunctionDefinition()) {
+  } else if (Symb.isFunctionDefinition()) {
     Result = SymbolRef::ST_Function;
   } else {
-    uint32_t Characteristics = 0;
-    if (!COFF::isReservedSectionNumber(Symb->SectionNumber)) {
-      const coff_section *Section = nullptr;
-      if (std::error_code EC = getSection(Symb->SectionNumber, Section))
-        return EC;
-      Characteristics = Section->Characteristics;
+      uint32_t Characteristics = 0;
+      if (!isReservedSectionNumber(Symb.getSectionNumber())) {
+        const coff_section *Section = nullptr;
+        if (std::error_code EC = getSection(Symb.getSectionNumber(), Section))
+          return EC;
+        Characteristics = Section->Characteristics;
     }
     if (Characteristics & COFF::IMAGE_SCN_MEM_READ &&
         ~Characteristics & COFF::IMAGE_SCN_MEM_WRITE) // Read only.
@@ -176,13 +186,13 @@
 }
 
 uint32_t COFFObjectFile::getSymbolFlags(DataRefImpl Ref) const {
-  const coff_symbol *Symb = toSymb(Ref);
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
   uint32_t Result = SymbolRef::SF_None;
 
   // TODO: Correctly set SF_FormatSpecific, SF_Common
 
-  if (Symb->SectionNumber == COFF::IMAGE_SYM_UNDEFINED) {
-    if (Symb->Value == 0)
+  if (Symb.getSectionNumber() == COFF::IMAGE_SYM_UNDEFINED) {
+    if (Symb.getValue() == 0)
       Result |= SymbolRef::SF_Undefined;
     else
       Result |= SymbolRef::SF_Common;
@@ -190,13 +200,13 @@
 
 
   // TODO: This are certainly too restrictive.
-  if (Symb->StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL)
+  if (Symb.getStorageClass() == COFF::IMAGE_SYM_CLASS_EXTERNAL)
     Result |= SymbolRef::SF_Global;
 
-  if (Symb->StorageClass == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL)
+  if (Symb.getStorageClass() == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL)
     Result |= SymbolRef::SF_Weak;
 
-  if (Symb->SectionNumber == COFF::IMAGE_SYM_ABSOLUTE)
+  if (Symb.getSectionNumber() == COFF::IMAGE_SYM_ABSOLUTE)
     Result |= SymbolRef::SF_Absolute;
 
   return Result;
@@ -207,15 +217,15 @@
   // FIXME: Return the correct size. This requires looking at all the symbols
   //        in the same section as this symbol, and looking for either the next
   //        symbol, or the end of the section.
-  const coff_symbol *Symb = toSymb(Ref);
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
   const coff_section *Section = nullptr;
-  if (std::error_code EC = getSection(Symb->SectionNumber, Section))
+  if (std::error_code EC = getSection(Symb.getSectionNumber(), Section))
     return EC;
 
-  if (Symb->SectionNumber == COFF::IMAGE_SYM_UNDEFINED)
+  if (Symb.getSectionNumber() == COFF::IMAGE_SYM_UNDEFINED)
     Result = UnknownAddressOrSize;
   else if (Section)
-    Result = Section->SizeOfRawData - Symb->Value;
+    Result = Section->SizeOfRawData - Symb.getValue();
   else
     Result = 0;
   return object_error::success;
@@ -224,12 +234,12 @@
 std::error_code
 COFFObjectFile::getSymbolSection(DataRefImpl Ref,
                                  section_iterator &Result) const {
-  const coff_symbol *Symb = toSymb(Ref);
-  if (COFF::isReservedSectionNumber(Symb->SectionNumber)) {
+  COFFSymbolRef Symb = getCOFFSymbol(Ref);
+  if (isReservedSectionNumber(Symb.getSectionNumber())) {
     Result = section_end();
   } else {
     const coff_section *Sec = nullptr;
-    if (std::error_code EC = getSection(Symb->SectionNumber, Sec))
+    if (std::error_code EC = getSection(Symb.getSectionNumber(), Sec))
       return EC;
     DataRefImpl Ref;
     Ref.p = reinterpret_cast<uintptr_t>(Sec);
@@ -336,9 +346,9 @@
                                                       DataRefImpl SymbRef,
                                                       bool &Result) const {
   const coff_section *Sec = toSec(SecRef);
-  const coff_symbol *Symb = toSymb(SymbRef);
+  COFFSymbolRef Symb = getCOFFSymbol(SymbRef);
   const coff_section *SymbSec = nullptr;
-  if (std::error_code EC = getSection(Symb->SectionNumber, SymbSec))
+  if (std::error_code EC = getSection(Symb.getSectionNumber(), SymbSec))
     return EC;
   if (SymbSec == Sec)
     Result = true;
@@ -395,17 +405,24 @@
 
 // Initialize the pointer to the symbol table.
 std::error_code COFFObjectFile::initSymbolTablePtr() {
-  if (std::error_code EC = getObject(
-          SymbolTable, Data, base() + COFFHeader->PointerToSymbolTable,
-          COFFHeader->NumberOfSymbols * sizeof(coff_symbol)))
-    return EC;
+  if (COFFHeader)
+    if (std::error_code EC =
+            getObject(SymbolTable16, Data, base() + getPointerToSymbolTable(),
+                      getNumberOfSymbols() * getSymbolTableEntrySize()))
+      return EC;
+
+  if (COFFBigObjHeader)
+    if (std::error_code EC =
+            getObject(SymbolTable32, Data, base() + getPointerToSymbolTable(),
+                      getNumberOfSymbols() * getSymbolTableEntrySize()))
+      return EC;
 
   // Find string table. The first four byte of the string table contains the
   // total size of the string table, including the size field itself. If the
   // string table is empty, the value of the first four byte would be 4.
   const uint8_t *StringTableAddr =
-      base() + COFFHeader->PointerToSymbolTable +
-      COFFHeader->NumberOfSymbols * sizeof(coff_symbol);
+      base() + getPointerToSymbolTable() +
+      getNumberOfSymbols() * getSymbolTableEntrySize();
   const ulittle32_t *StringTableSizePtr;
   if (std::error_code EC = getObject(StringTableSizePtr, Data, StringTableAddr))
     return EC;
@@ -511,9 +528,10 @@
 
 COFFObjectFile::COFFObjectFile(MemoryBufferRef Object, std::error_code &EC)
     : ObjectFile(Binary::ID_COFF, Object), COFFHeader(nullptr),
-      PE32Header(nullptr), PE32PlusHeader(nullptr), DataDirectory(nullptr),
-      SectionTable(nullptr), SymbolTable(nullptr), StringTable(nullptr),
-      StringTableSize(0), ImportDirectory(nullptr), NumberOfImportDirectory(0),
+      COFFBigObjHeader(nullptr), PE32Header(nullptr), PE32PlusHeader(nullptr),
+      DataDirectory(nullptr), SectionTable(nullptr), SymbolTable16(nullptr),
+      SymbolTable32(nullptr), StringTable(nullptr), StringTableSize(0),
+      ImportDirectory(nullptr), NumberOfImportDirectory(0),
       ExportDirectory(nullptr) {
   // Check that we at least have enough room for a header.
   if (!checkSize(Data, EC, sizeof(coff_file_header)))
@@ -534,17 +552,46 @@
       return;
     CurPtr = *reinterpret_cast<const ulittle16_t *>(base() + 0x3c);
     // Check the PE magic bytes. ("PE\0\0")
-    if (std::memcmp(base() + CurPtr, "PE\0\0", 4) != 0) {
+    if (std::memcmp(base() + CurPtr, COFF::PEMagic, sizeof(COFF::PEMagic)) !=
+        0) {
       EC = object_error::parse_failed;
       return;
     }
-    CurPtr += 4; // Skip the PE magic bytes.
+    CurPtr += sizeof(COFF::PEMagic); // Skip the PE magic bytes.
     HasPEHeader = true;
   }
 
   if ((EC = getObject(COFFHeader, Data, base() + CurPtr)))
     return;
-  CurPtr += sizeof(coff_file_header);
+
+  // It might be a bigobj file, let's check.  Note that COFF bigobj and COFF
+  // import libraries share a common prefix but bigobj is more restrictive.
+  if (!HasPEHeader && COFFHeader->Machine == COFF::IMAGE_FILE_MACHINE_UNKNOWN &&
+      COFFHeader->NumberOfSections == uint16_t(0xffff) &&
+      checkSize(Data, EC, sizeof(coff_bigobj_file_header))) {
+    if ((EC = getObject(COFFBigObjHeader, Data, base() + CurPtr)))
+      return;
+
+    // Verify that we are dealing with bigobj.
+    if (COFFBigObjHeader->Version >= COFF::BigObjHeader::MinBigObjectVersion &&
+        std::memcmp(COFFBigObjHeader->UUID, COFF::BigObjMagic,
+                    sizeof(COFF::BigObjMagic)) == 0) {
+      COFFHeader = nullptr;
+      CurPtr += sizeof(coff_bigobj_file_header);
+    } else {
+      // It's not a bigobj.
+      COFFBigObjHeader = nullptr;
+    }
+  }
+  if (COFFHeader) {
+    // The prior checkSize call may have failed.  This isn't a hard error
+    // because we were just trying to sniff out bigobj.
+    EC = object_error::success;
+    CurPtr += sizeof(coff_file_header);
+
+    if (COFFHeader->isImportLibrary())
+      return;
+  }
 
   if (HasPEHeader) {
     const pe32_header *Header;
@@ -571,15 +618,12 @@
     CurPtr += COFFHeader->SizeOfOptionalHeader;
   }
 
-  if (COFFHeader->isImportLibrary())
-    return;
-
   if ((EC = getObject(SectionTable, Data, base() + CurPtr,
-                      COFFHeader->NumberOfSections * sizeof(coff_section))))
+                      getNumberOfSections() * sizeof(coff_section))))
     return;
 
   // Initialize the pointer to the symbol table.
-  if (COFFHeader->PointerToSymbolTable != 0)
+  if (getPointerToSymbolTable() != 0)
     if ((EC = initSymbolTablePtr()))
       return;
 
@@ -596,7 +640,7 @@
 
 basic_symbol_iterator COFFObjectFile::symbol_begin_impl() const {
   DataRefImpl Ret;
-  Ret.p = reinterpret_cast<uintptr_t>(SymbolTable);
+  Ret.p = getSymbolTable();
   return basic_symbol_iterator(SymbolRef(Ret, this));
 }
 
@@ -638,8 +682,8 @@
 
 section_iterator COFFObjectFile::section_end() const {
   DataRefImpl Ret;
-  int NumSections = COFFHeader->isImportLibrary()
-      ? 0 : COFFHeader->NumberOfSections;
+  int NumSections =
+      COFFHeader && COFFHeader->isImportLibrary() ? 0 : getNumberOfSections();
   Ret.p = reinterpret_cast<uintptr_t>(SectionTable + NumSections);
   return section_iterator(SectionRef(Ret, this));
 }
@@ -649,7 +693,7 @@
 }
 
 StringRef COFFObjectFile::getFileFormatName() const {
-  switch(COFFHeader->Machine) {
+  switch(getMachine()) {
   case COFF::IMAGE_FILE_MACHINE_I386:
     return "COFF-i386";
   case COFF::IMAGE_FILE_MACHINE_AMD64:
@@ -662,7 +706,7 @@
 }
 
 unsigned COFFObjectFile::getArch() const {
-  switch(COFFHeader->Machine) {
+  switch (getMachine()) {
   case COFF::IMAGE_FILE_MACHINE_I386:
     return Triple::x86;
   case COFF::IMAGE_FILE_MACHINE_AMD64:
@@ -715,9 +759,9 @@
 std::error_code COFFObjectFile::getSection(int32_t Index,
                                            const coff_section *&Result) const {
   // Check for special index values.
-  if (COFF::isReservedSectionNumber(Index))
+  if (isReservedSectionNumber(Index))
     Result = nullptr;
-  else if (Index > 0 && Index <= COFFHeader->NumberOfSections)
+  else if (Index > 0 && static_cast<uint32_t>(Index) <= getNumberOfSections())
     // We already verified the section table data, so no need to check again.
     Result = SectionTable + (Index - 1);
   else
@@ -736,65 +780,68 @@
   return object_error::success;
 }
 
-std::error_code COFFObjectFile::getSymbol(uint32_t Index,
-                                          const coff_symbol *&Result) const {
-  if (Index < COFFHeader->NumberOfSymbols)
-    Result = SymbolTable + Index;
+template <typename coff_symbol_type>
+std::error_code
+COFFObjectFile::getSymbol(uint32_t Index,
+                          const coff_symbol_type *&Result) const {
+  if (Index < getNumberOfSymbols())
+    Result = reinterpret_cast<coff_symbol_type *>(getSymbolTable()) + Index;
   else
     return object_error::parse_failed;
   return object_error::success;
 }
 
-std::error_code COFFObjectFile::getSymbolName(const coff_symbol *Symbol,
+std::error_code COFFObjectFile::getSymbolName(COFFSymbolRef Symbol,
                                               StringRef &Res) const {
   // Check for string table entry. First 4 bytes are 0.
-  if (Symbol->Name.Offset.Zeroes == 0) {
-    uint32_t Offset = Symbol->Name.Offset.Offset;
+  if (Symbol.getStringTableOffset().Zeroes == 0) {
+    uint32_t Offset = Symbol.getStringTableOffset().Offset;
     if (std::error_code EC = getString(Offset, Res))
       return EC;
     return object_error::success;
   }
 
-  if (Symbol->Name.ShortName[7] == 0)
+  if (Symbol.getShortName()[COFF::NameSize - 1] == 0)
     // Null terminated, let ::strlen figure out the length.
-    Res = StringRef(Symbol->Name.ShortName);
+    Res = StringRef(Symbol.getShortName());
   else
     // Not null terminated, use all 8 bytes.
-    Res = StringRef(Symbol->Name.ShortName, 8);
+    Res = StringRef(Symbol.getShortName(), COFF::NameSize);
   return object_error::success;
 }
 
-ArrayRef<uint8_t> COFFObjectFile::getSymbolAuxData(
-                                  const coff_symbol *Symbol) const {
+ArrayRef<uint8_t>
+COFFObjectFile::getSymbolAuxData(COFFSymbolRef Symbol) const {
   const uint8_t *Aux = nullptr;
 
-  if (Symbol->NumberOfAuxSymbols > 0) {
-  // AUX data comes immediately after the symbol in COFF
-    Aux = reinterpret_cast<const uint8_t *>(Symbol + 1);
+  size_t SymbolSize = getSymbolTableEntrySize();
+  if (Symbol.getNumberOfAuxSymbols() > 0) {
+    // AUX data comes immediately after the symbol in COFF
+    Aux = reinterpret_cast<const uint8_t *>(Symbol.getRawPtr()) + SymbolSize;
 # ifndef NDEBUG
     // Verify that the Aux symbol points to a valid entry in the symbol table.
     uintptr_t Offset = uintptr_t(Aux) - uintptr_t(base());
-    if (Offset < COFFHeader->PointerToSymbolTable
-        || Offset >= COFFHeader->PointerToSymbolTable
-           + (COFFHeader->NumberOfSymbols * sizeof(coff_symbol)))
+    if (Offset < getPointerToSymbolTable() ||
+        Offset >=
+            getPointerToSymbolTable() + (getNumberOfSymbols() * SymbolSize))
       report_fatal_error("Aux Symbol data was outside of symbol table.");
 
-    assert((Offset - COFFHeader->PointerToSymbolTable) % sizeof(coff_symbol)
-         == 0 && "Aux Symbol data did not point to the beginning of a symbol");
+    assert((Offset - getPointerToSymbolTable()) % SymbolSize == 0 &&
+           "Aux Symbol data did not point to the beginning of a symbol");
 # endif
   }
-  return makeArrayRef(Aux, Symbol->NumberOfAuxSymbols * sizeof(coff_symbol));
+  return makeArrayRef(Aux, Symbol.getNumberOfAuxSymbols() * SymbolSize);
 }
 
 std::error_code COFFObjectFile::getSectionName(const coff_section *Sec,
                                                StringRef &Res) const {
   StringRef Name;
-  if (Sec->Name[7] == 0)
+  if (Sec->Name[COFF::NameSize - 1] == 0)
     // Null terminated, let ::strlen figure out the length.
     Name = Sec->Name;
   else
     // Not null terminated, use all 8 bytes.
-    Name = StringRef(Sec->Name, 8);
+    Name = StringRef(Sec->Name, COFF::NameSize);
 
   // Check for string table entry. First byte is '/'.
   if (Name[0] == '/') {
@@ -850,9 +897,14 @@
 }
 
 symbol_iterator COFFObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
-  const coff_relocation* R = toRel(Rel);
+  const coff_relocation *R = toRel(Rel);
   DataRefImpl Ref;
-  Ref.p = reinterpret_cast<uintptr_t>(SymbolTable + R->SymbolTableIndex);
+  if (SymbolTable16)
+    Ref.p = reinterpret_cast<uintptr_t>(SymbolTable16 + R->SymbolTableIndex);
+  else if (SymbolTable32)
+    Ref.p = reinterpret_cast<uintptr_t>(SymbolTable32 + R->SymbolTableIndex);
+  else
+    llvm_unreachable("no symbol table pointer!");
   return symbol_iterator(SymbolRef(Ref, this));
 }
 
@@ -868,9 +920,16 @@
   return toSec(Section.getRawDataRefImpl());
 }
 
-const coff_symbol *
-COFFObjectFile::getCOFFSymbol(const SymbolRef &Symbol) const {
-  return toSymb(Symbol.getRawDataRefImpl());
+COFFSymbolRef COFFObjectFile::getCOFFSymbol(const DataRefImpl &Ref) const {
+  if (SymbolTable16)
+    return toSymb<coff_symbol16>(Ref);
+  if (SymbolTable32)
+    return toSymb<coff_symbol32>(Ref);
+  llvm_unreachable("no symbol table pointer!");
+}
+
+COFFSymbolRef COFFObjectFile::getCOFFSymbol(const SymbolRef &Symbol) const {
+  return getCOFFSymbol(Symbol.getRawDataRefImpl());
 }
 
 const coff_relocation *
@@ -888,7 +947,7 @@
                                       SmallVectorImpl<char> &Result) const {
   const coff_relocation *Reloc = toRel(Rel);
   StringRef Res;
-  switch (COFFHeader->Machine) {
+  switch (getMachine()) {
   case COFF::IMAGE_FILE_MACHINE_AMD64:
     switch (Reloc->Type) {
     LLVM_COFF_SWITCH_RELOC_TYPE_NAME(IMAGE_REL_AMD64_ABSOLUTE);
@@ -963,11 +1022,11 @@
 COFFObjectFile::getRelocationValueString(DataRefImpl Rel,
                                          SmallVectorImpl<char> &Result) const {
   const coff_relocation *Reloc = toRel(Rel);
-  const coff_symbol *Symb = nullptr;
-  if (std::error_code EC = getSymbol(Reloc->SymbolTableIndex, Symb))
-    return EC;
   DataRefImpl Sym;
-  Sym.p = reinterpret_cast<uintptr_t>(Symb);
+  ErrorOr<COFFSymbolRef> Symb = getSymbol(Reloc->SymbolTableIndex);
+  if (std::error_code EC = Symb.getError())
+    return EC;
+  Sym.p = reinterpret_cast<uintptr_t>(Symb->getRawPtr());
   StringRef SymName;
   if (std::error_code EC = getSymbolName(Sym, SymName))
     return EC;
Index: test/MC/ARM/coff-file.s
===================================================================
--- test/MC/ARM/coff-file.s
+++ test/MC/ARM/coff-file.s
@@ -21,7 +21,7 @@
 // CHECK-SCN: Symbols [
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: null-padded.asm
@@ -29,7 +29,7 @@
 // CHECK-SCN:   }
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: eighteen-chars.asm
@@ -37,7 +37,7 @@
 // CHECK-SCN:   }
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: multiple-auxiliary-entries.asm
Index: test/MC/COFF/alias.s
===================================================================
--- test/MC/COFF/alias.s
+++ test/MC/COFF/alias.s
@@ -92,7 +92,6 @@
 // CHECK-NEXT:     AuxWeakExternal {
 // CHECK-NEXT:       Linked: external2
 // CHECK-NEXT:       Search: Library (0x2)
-// CHECK-NEXT:       Unused: (00 00 00 00 00 00 00 00 00 00)
 // CHECK-NEXT:     }
 // CHECK-NEXT:   }
 // CHECK-NEXT:   Symbol {
Index: test/MC/COFF/basic-coff-64.s
===================================================================
--- test/MC/COFF/basic-coff-64.s
+++ test/MC/COFF/basic-coff-64.s
@@ -113,7 +113,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: [[DataNum]]
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
Index: test/MC/COFF/basic-coff.s
===================================================================
--- test/MC/COFF/basic-coff.s
+++ test/MC/COFF/basic-coff.s
@@ -113,7 +113,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: 2
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
Index: test/MC/COFF/feat00.s
===================================================================
--- test/MC/COFF/feat00.s
+++ test/MC/COFF/feat00.s
@@ -6,7 +6,7 @@
 // CHECK: Symbol {
 // CHECK:   Name: @feat.00
 // CHECK:   Value: 123
-// CHECK:   Section: (65535)
+// CHECK:   Section: (-1)
 // CHECK:   BaseType: Null (0x0)
 // CHECK:   ComplexType: Null (0x0)
 // CHECK:   StorageClass: External (0x2)
Index: test/MC/COFF/file.s
===================================================================
--- test/MC/COFF/file.s
+++ test/MC/COFF/file.s
@@ -21,7 +21,7 @@
 // CHECK-SCN: Symbols [
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: null-padded.asm
@@ -29,7 +29,7 @@
 // CHECK-SCN:   }
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: eighteen-chars.asm
@@ -37,7 +37,7 @@
 // CHECK-SCN:   }
 // CHECK-SCN:   Symbol {
 // CHECK-SCN:     Name: .file
-// CHECK-SCN:     Section: (65534)
+// CHECK-SCN:     Section: (-2)
 // CHECK-SCN:     StorageClass: File
 // CHECK-SCN:     AuxFileRecord {
 // CHECK-SCN:       FileName: multiple-auxiliary-entries.asm
Index: test/MC/COFF/symbol-fragment-offset-64.s
===================================================================
--- test/MC/COFF/symbol-fragment-offset-64.s
+++ test/MC/COFF/symbol-fragment-offset-64.s
@@ -117,7 +117,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: 1
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
@@ -135,7 +134,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: 2
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
Index: test/MC/COFF/symbol-fragment-offset.s
===================================================================
--- test/MC/COFF/symbol-fragment-offset.s
+++ test/MC/COFF/symbol-fragment-offset.s
@@ -117,7 +117,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: 1
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
@@ -135,7 +134,6 @@
 // CHECK:       Checksum: 0x0
 // CHECK:       Number: 2
 // CHECK:       Selection: 0x0
-// CHECK:       Unused: (00 00 00)
 // CHECK:     }
 // CHECK:   }
 // CHECK:   Symbol {
Index: test/MC/COFF/weak.s
===================================================================
--- test/MC/COFF/weak.s
+++ test/MC/COFF/weak.s
@@ -45,14 +45,13 @@
 // CHECK-NEXT:   AuxWeakExternal {
 // CHECK-NEXT:     Linked: .weak._test_weak.default
 // CHECK-NEXT:      Search: Library
-// CHECK-NEXT:      Unused: (00 00 00 00 00 00 00 00 00 00)
 // CHECK-NEXT:   }
 // CHECK-NEXT: }
 
 // CHECK:      Symbol {
 // CHECK:        Name:                .weak._test_weak.default
 // CHECK-NEXT:   Value:               0
-// CHECK-NEXT:   Section:             (65535)
+// CHECK-NEXT:   Section:             (-1)
 // CHECK-NEXT:   BaseType:            Null
 // CHECK-NEXT:   ComplexType:         Null
 // CHECK-NEXT:   StorageClass:        External
@@ -70,6 +69,5 @@
 // CHECK-NEXT:   AuxWeakExternal {
 // CHECK-NEXT:     Linked: _main
 // CHECK-NEXT:      Search: Library
-// CHECK-NEXT:      Unused: (00 00 00 00 00 00 00 00 00 00)
 // CHECK-NEXT:   }
 // CHECK-NEXT: }
Index: test/tools/llvm-readobj/bigobj.test
===================================================================
--- /dev/null
+++ test/tools/llvm-readobj/bigobj.test
@@ -0,0 +1,139 @@
+RUN: llvm-readobj --file-headers --sections --symbols --relocations %p/Inputs/bigobj.coff-x86-64 | FileCheck %s
+
+CHECK:      File: {{(.*[/\\])?}}bigobj.coff-x86-64
+CHECK-NEXT: Format: COFF-x86-64
+CHECK-NEXT: Arch: x86_64
+CHECK-NEXT: AddressSize: 64bit
+CHECK-NEXT: ImageFileHeader {
+CHECK-NEXT:   Machine: IMAGE_FILE_MACHINE_AMD64 (0x8664)
+CHECK-NEXT:   SectionCount: 3
+CHECK-NEXT:   TimeDateStamp: 1970-01-01 00:00:00 (0x0)
+CHECK-NEXT:   PointerToSymbolTable: 0xB0
+CHECK-NEXT:   SymbolCount: 8
+CHECK-NEXT:   OptionalHeaderSize: 0
+CHECK-NEXT:   Characteristics [ (0x0)
+CHECK-NEXT:   ]
+CHECK-NEXT: }
+CHECK-NEXT: Sections [
+CHECK-NEXT:   Section {
+CHECK-NEXT:     Number: 1
+CHECK-NEXT:     Name: .text (2E 74 65 78 74 00 00 00)
+CHECK-NEXT:     VirtualSize: 0x0
+CHECK-NEXT:     VirtualAddress: 0x0
+CHECK-NEXT:     RawDataSize: 0
+CHECK-NEXT:     PointerToRawData: 0x0
+CHECK-NEXT:     PointerToRelocations: 0x0
+CHECK-NEXT:     PointerToLineNumbers: 0x0
+CHECK-NEXT:     RelocationCount: 0
+CHECK-NEXT:     LineNumberCount: 0
+CHECK-NEXT:     Characteristics [ (0x60500020)
+CHECK-NEXT:       IMAGE_SCN_ALIGN_16BYTES (0x500000)
+CHECK-NEXT:       IMAGE_SCN_CNT_CODE (0x20)
+CHECK-NEXT:       IMAGE_SCN_MEM_EXECUTE (0x20000000)
+CHECK-NEXT:       IMAGE_SCN_MEM_READ (0x40000000)
+CHECK-NEXT:     ]
+CHECK-NEXT:   }
+CHECK-NEXT:   Section {
+CHECK-NEXT:     Number: 2
+CHECK-NEXT:     Name: .data (2E 64 61 74 61 00 00 00)
+CHECK-NEXT:     VirtualSize: 0x0
+CHECK-NEXT:     VirtualAddress: 0x0
+CHECK-NEXT:     RawDataSize: 0
+CHECK-NEXT:     PointerToRawData: 0x0
+CHECK-NEXT:     PointerToRelocations: 0x0
+CHECK-NEXT:     PointerToLineNumbers: 0x0
+CHECK-NEXT:     RelocationCount: 0
+CHECK-NEXT:     LineNumberCount: 0
+CHECK-NEXT:     Characteristics [ (0xC0500040)
+CHECK-NEXT:       IMAGE_SCN_ALIGN_16BYTES (0x500000)
+CHECK-NEXT:       IMAGE_SCN_CNT_INITIALIZED_DATA (0x40)
+CHECK-NEXT:       IMAGE_SCN_MEM_READ (0x40000000)
+CHECK-NEXT:       IMAGE_SCN_MEM_WRITE (0x80000000)
+CHECK-NEXT:     ]
+CHECK-NEXT:   }
+CHECK-NEXT:   Section {
+CHECK-NEXT:     Number: 3
+CHECK-NEXT:     Name: .bss (2E 62 73 73 00 00 00 00)
+CHECK-NEXT:     VirtualSize: 0x0
+CHECK-NEXT:     VirtualAddress: 0x0
+CHECK-NEXT:     RawDataSize: 0
+CHECK-NEXT:     PointerToRawData: 0x0
+CHECK-NEXT:     PointerToRelocations: 0x0
+CHECK-NEXT:     PointerToLineNumbers: 0x0
+CHECK-NEXT:     RelocationCount: 0
+CHECK-NEXT:     LineNumberCount: 0
+CHECK-NEXT:     Characteristics [ (0xC0500080)
+CHECK-NEXT:       IMAGE_SCN_ALIGN_16BYTES (0x500000)
+CHECK-NEXT:       IMAGE_SCN_CNT_UNINITIALIZED_DATA (0x80)
+CHECK-NEXT:       IMAGE_SCN_MEM_READ (0x40000000)
+CHECK-NEXT:       IMAGE_SCN_MEM_WRITE (0x80000000)
+CHECK-NEXT:     ]
+CHECK-NEXT:   }
+CHECK-NEXT: ]
+CHECK-NEXT: Relocations [
+CHECK-NEXT: ]
+CHECK-NEXT: Symbols [
+CHECK-NEXT:   Symbol {
+CHECK-NEXT:     Name: .file
+CHECK-NEXT:     Value: 0
+CHECK-NEXT:     Section:  (-2)
+CHECK-NEXT:     BaseType: Null (0x0)
+CHECK-NEXT:     ComplexType: Null (0x0)
+CHECK-NEXT:     StorageClass: File (0x67)
+CHECK-NEXT:     AuxSymbolCount: 1
+CHECK-NEXT:     AuxFileRecord {
+CHECK-NEXT:       FileName: fake
+CHECK-NEXT:     }
+CHECK-NEXT:   }
+CHECK-NEXT:   Symbol {
+CHECK-NEXT:     Name: .text
+CHECK-NEXT:     Value: 0
+CHECK-NEXT:     Section: .text (1)
+CHECK-NEXT:     BaseType: Null (0x0)
+CHECK-NEXT:     ComplexType: Null (0x0)
+CHECK-NEXT:     StorageClass: Static (0x3)
+CHECK-NEXT:     AuxSymbolCount: 1
+CHECK-NEXT:     AuxSectionDef {
+CHECK-NEXT:       Length: 0
+CHECK-NEXT:       RelocationCount: 0
+CHECK-NEXT:       LineNumberCount: 0
+CHECK-NEXT:       Checksum: 0x0
+CHECK-NEXT:       Number: 0
+CHECK-NEXT:       Selection: 0x0
+CHECK-NEXT:     }
+CHECK-NEXT:   }
+CHECK-NEXT:   Symbol {
+CHECK-NEXT:     Name: .data
+CHECK-NEXT:     Value: 0
+CHECK-NEXT:     Section: .data (2)
+CHECK-NEXT:     BaseType: Null (0x0)
+CHECK-NEXT:     ComplexType: Null (0x0)
+CHECK-NEXT:     StorageClass: Static (0x3)
+CHECK-NEXT:     AuxSymbolCount: 1
+CHECK-NEXT:     AuxSectionDef {
+CHECK-NEXT:       Length: 0
+CHECK-NEXT:       RelocationCount: 0
+CHECK-NEXT:       LineNumberCount: 0
+CHECK-NEXT:       Checksum: 0x0
+CHECK-NEXT:       Number: 0
+CHECK-NEXT:       Selection: 0x0
+CHECK-NEXT:     }
+CHECK-NEXT:   }
+CHECK-NEXT:   Symbol {
+CHECK-NEXT:     Name: .bss
+CHECK-NEXT:     Value: 0
+CHECK-NEXT:     Section: .bss (3)
+CHECK-NEXT:     BaseType: Null (0x0)
+CHECK-NEXT:     ComplexType: Null (0x0)
+CHECK-NEXT:     StorageClass: Static (0x3)
+CHECK-NEXT:     AuxSymbolCount: 1
+CHECK-NEXT:     AuxSectionDef {
+CHECK-NEXT:       Length: 0
+CHECK-NEXT:       RelocationCount: 0
+CHECK-NEXT:       LineNumberCount: 0
+CHECK-NEXT:       Checksum: 0x0
+CHECK-NEXT:       Number: 0
+CHECK-NEXT:       Selection: 0x0
+CHECK-NEXT:     }
+CHECK-NEXT:   }
+CHECK-NEXT: ]
Index: test/tools/llvm-readobj/coff-file-sections-reading.test
===================================================================
--- test/tools/llvm-readobj/coff-file-sections-reading.test
+++ test/tools/llvm-readobj/coff-file-sections-reading.test
@@ -4,7 +4,7 @@
 CHECK:   Symbol {
 CHECK:     Name: .file
 CHECK:     Value: 0
-CHECK:     Section:  (65534)
+CHECK:     Section:  (-2)
 CHECK:     BaseType: Null (0x0)
 CHECK:     ComplexType: Null (0x0)
 CHECK:     StorageClass: File (0x67)
Index: test/tools/llvm-readobj/cxx-cli-aux.test
===================================================================
--- test/tools/llvm-readobj/cxx-cli-aux.test
+++ test/tools/llvm-readobj/cxx-cli-aux.test
@@ -9,7 +9,7 @@
 CHECK:        Symbol {
 CHECK:          Name: ?PerAppDomain@@$$Q3HA
 CHECK-NEXT:     Value: 4
-CHECK-NEXT:     Section:  (65535)
+CHECK-NEXT:     Section:  (-1)
 CHECK-NEXT:     BaseType: Null (0x0)
 CHECK-NEXT:     ComplexType: Null (0x0)
 CHECK-NEXT:     StorageClass: External (0x2)
@@ -21,14 +21,13 @@
 CHECK-NEXT:       Checksum: 0x0
 CHECK-NEXT:       Number: 0
 CHECK-NEXT:       Selection: NoDuplicates (0x1)
-CHECK-NEXT:       Unused: (00 00 00)
 CHECK-NEXT:     }
 CHECK-NEXT:   }
 
 CHECK:        Symbol {
 CHECK:          Name: 04000001
 CHECK-NEXT:     Value: 4
-CHECK-NEXT:     Section:  (65535)
+CHECK-NEXT:     Section:  (-1)
 CHECK-NEXT:     BaseType: Null (0x0)
 CHECK-NEXT:     ComplexType: Null (0x0)
 CHECK-NEXT:     StorageClass: CLRToken (0x6B)
@@ -37,6 +36,5 @@
 CHECK-NEXT:       AuxType: 1
 CHECK-NEXT:       Reserved: 0
 CHECK-NEXT:       SymbolTableIndex: ?PerAppDomain@@$$Q3HA (19)
-CHECK-NEXT:       Unused: (00 00 00 00 00 00 00 00 00 00 00 00)
 CHECK-NEXT:     }
 CHECK-NEXT:   }
Index: test/tools/llvm-readobj/sections-ext.test
===================================================================
--- test/tools/llvm-readobj/sections-ext.test
+++ test/tools/llvm-readobj/sections-ext.test
@@ -52,7 +52,6 @@
 COFF-NEXT:           Checksum: 0x0
 COFF-NEXT:           Number: 1
 COFF-NEXT:           Selection: 0x0
-COFF-NEXT:           Unused: (00 00 00)
 COFF-NEXT:         }
 COFF-NEXT:       }
 COFF-NEXT:       Symbol {
Index: test/tools/llvm-readobj/symbols.test
===================================================================
--- test/tools/llvm-readobj/symbols.test
+++ test/tools/llvm-readobj/symbols.test
@@ -7,7 +7,7 @@
 COFF-NEXT:   Symbol {
 COFF-NEXT:     Name: @comp.id
 COFF-NEXT:    Value: 14766605
-COFF-NEXT:    Section:  (65535)
+COFF-NEXT:    Section:  (-1)
 COFF-NEXT:     BaseType: Null (0x0)
 COFF-NEXT:     ComplexType: Null (0x0)
 COFF-NEXT:    StorageClass: Static (0x3)
@@ -16,7 +16,7 @@
 COFF-NEXT:   Symbol {
 COFF-NEXT:    Name: @feat.00
 COFF-NEXT:    Value: 2147484049
-COFF-NEXT:     Section:  (65535)
+COFF-NEXT:     Section:  (-1)
 COFF-NEXT:     BaseType: Null (0x0)
 COFF-NEXT:    ComplexType: Null (0x0)
 COFF-NEXT:    StorageClass: Static (0x3)
@@ -37,7 +37,6 @@
 COFF-NEXT:       Checksum: 0x0
 COFF-NEXT:       Number: 1
 COFF-NEXT:       Selection: 0x0
-COFF-NEXT:       Unused: (00 00 00)
 COFF-NEXT:     }
 COFF-NEXT:   }
 
Index: tools/llvm-nm/llvm-nm.cpp
===================================================================
--- tools/llvm-nm/llvm-nm.cpp
+++ tools/llvm-nm/llvm-nm.cpp
@@ -686,7 +686,7 @@
 }
 
 static char getSymbolNMTypeChar(COFFObjectFile &Obj, symbol_iterator I) {
-  const coff_symbol *Symb = Obj.getCOFFSymbol(*I);
+  COFFSymbolRef Symb = Obj.getCOFFSymbol(*I);
   // OK, this is COFF.
   symbol_iterator SymI(I);
 
@@ -703,7 +703,7 @@
     return Ret;
 
   uint32_t Characteristics = 0;
-  if (!COFF::isReservedSectionNumber(Symb->SectionNumber)) {
+  if (!Obj.isReservedSectionNumber(Symb.getSectionNumber())) {
     section_iterator SecI = Obj.section_end();
     if (error(SymI->getSection(SecI)))
       return '?';
@@ -711,7 +711,7 @@
     Characteristics = Section->Characteristics;
   }
 
-  switch (Symb->SectionNumber) {
+  switch (Symb.getSectionNumber()) {
   case COFF::IMAGE_SYM_DEBUG:
     return 'n';
   default:
@@ -729,7 +729,7 @@
       return 'i';
 
     // Check for section symbol.
-    else if (Symb->isSectionDefinition())
+    else if (Symb.isSectionDefinition())
       return 's';
   }
 
Index: tools/llvm-objdump/COFFDump.cpp
===================================================================
--- tools/llvm-objdump/COFFDump.cpp
+++ tools/llvm-objdump/COFFDump.cpp
@@ -260,11 +260,8 @@
   if (!PE32Header)
     return;
 
-  const coff_file_header *Header;
-  if (error(Obj->getCOFFHeader(Header)))
-    return;
   // Currently only x86 is supported
-  if (Header->Machine != COFF::IMAGE_FILE_MACHINE_I386)
+  if (Obj->getMachine() != COFF::IMAGE_FILE_MACHINE_I386)
     return;
 
   const data_directory *DataDir;
@@ -518,11 +515,7 @@
 }
 
 void llvm::printCOFFUnwindInfo(const COFFObjectFile *Obj) {
-  const coff_file_header *Header;
-  if (error(Obj->getCOFFHeader(Header)))
-    return;
-
-  if (Header->Machine != COFF::IMAGE_FILE_MACHINE_AMD64) {
+  if (Obj->getMachine() != COFF::IMAGE_FILE_MACHINE_AMD64) {
     errs() << "Unsupported image machine type "
               "(currently only AMD64 is supported).\n";
     return;
Index: tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- tools/llvm-objdump/llvm-objdump.cpp
+++ tools/llvm-objdump/llvm-objdump.cpp
@@ -564,29 +564,25 @@
 }
 
 static void PrintCOFFSymbolTable(const COFFObjectFile *coff) {
-  const coff_file_header *header;
-  if (error(coff->getHeader(header)))
-    return;
-
-  for (unsigned SI = 0, SE = header->NumberOfSymbols; SI != SE; ++SI) {
-    const coff_symbol *Symbol;
+  for (unsigned SI = 0, SE = coff->getNumberOfSymbols(); SI != SE; ++SI) {
+    ErrorOr<COFFSymbolRef> Symbol = coff->getSymbol(SI);
     StringRef Name;
-    if (error(coff->getSymbol(SI, Symbol)))
+    if (error(Symbol.getError()))
       return;
 
-    if (error(coff->getSymbolName(Symbol, Name)))
+    if (error(coff->getSymbolName(*Symbol, Name)))
       return;
 
     outs() << "[" << format("%2d", SI) << "]"
-           << "(sec " << format("%2d", int(Symbol->SectionNumber)) << ")"
+           << "(sec " << format("%2d", int(Symbol->getSectionNumber())) << ")"
            << "(fl 0x00)" // Flag bits, which COFF doesn't have.
-           << "(ty " << format("%3x", unsigned(Symbol->Type)) << ")"
-           << "(scl " << format("%3x", unsigned(Symbol->StorageClass)) << ") "
-           << "(nx " << unsigned(Symbol->NumberOfAuxSymbols) << ") "
-           << "0x" << format("%08x", unsigned(Symbol->Value)) << " "
+           << "(ty " << format("%3x", unsigned(Symbol->getType())) << ")"
+           << "(scl " << format("%3x", unsigned(Symbol->getStorageClass())) << ") "
+           << "(nx " << unsigned(Symbol->getNumberOfAuxSymbols()) << ") "
+           << "0x" << format("%08x", unsigned(Symbol->getValue())) << " "
            << Name << "\n";
 
-    for (unsigned AI = 0, AE = Symbol->NumberOfAuxSymbols; AI < AE; ++AI, ++SI) {
+    for (unsigned AI = 0, AE = Symbol->getNumberOfAuxSymbols(); AI < AE; ++AI, ++SI) {
       if (Symbol->isSectionDefinition()) {
         const coff_aux_section_definition *asd;
         if (error(coff->getAuxSymbol<coff_aux_section_definition>(SI + 1, asd)))
@@ -602,15 +598,15 @@
                          , unsigned(asd->Number)
                          , unsigned(asd->Selection));
       } else if (Symbol->isFileRecord()) {
-        const coff_aux_file *AF;
-        if (error(coff->getAuxSymbol<coff_aux_file>(SI + 1, AF)))
+        const char *FileName;
+        if (error(coff->getAuxSymbol<char>(SI + 1, FileName)))
           return;
 
-        StringRef Name(AF->FileName,
-                       Symbol->NumberOfAuxSymbols * COFF::SymbolSize);
+        StringRef Name(FileName, Symbol->getNumberOfAuxSymbols() *
+                                     coff->getSymbolTableEntrySize());
         outs() << "AUX " << Name.rtrim(StringRef("\0", 1))  << '\n';
 
-        SI = SI + Symbol->NumberOfAuxSymbols;
+        SI = SI + Symbol->getNumberOfAuxSymbols();
         break;
       } else {
         outs() << "AUX Unknown\n";
Index: tools/llvm-readobj/COFFDumper.cpp
===================================================================
--- tools/llvm-readobj/COFFDumper.cpp
+++ tools/llvm-readobj/COFFDumper.cpp
@@ -313,9 +313,10 @@
 
 template <typename T>
 static std::error_code getSymbolAuxData(const COFFObjectFile *Obj,
-                                        const coff_symbol *Symbol,
-                                        const T *&Aux) {
+                                        COFFSymbolRef Symbol,
+                                        uint8_t AuxSymbolIdx, const T *&Aux) {
   ArrayRef<uint8_t> AuxData = Obj->getSymbolAuxData(Symbol);
+  AuxData = AuxData.slice(AuxSymbolIdx * Obj->getSymbolTableEntrySize());
   Aux = reinterpret_cast<const T*>(AuxData.data());
   return readobj_error::success;
 }
@@ -342,25 +343,20 @@
 }
 
 void COFFDumper::printFileHeaders() {
-  // Print COFF header
-  const coff_file_header *COFFHeader = nullptr;
-  if (error(Obj->getCOFFHeader(COFFHeader)))
-    return;
-
-  time_t TDS = COFFHeader->TimeDateStamp;
+  time_t TDS = Obj->getTimeDateStamp();
   char FormattedTime[20] = { };
   strftime(FormattedTime, 20, "%Y-%m-%d %H:%M:%S", gmtime(&TDS));
 
   {
     DictScope D(W, "ImageFileHeader");
-    W.printEnum  ("Machine", COFFHeader->Machine,
+    W.printEnum  ("Machine", Obj->getMachine(),
                     makeArrayRef(ImageFileMachineType));
-    W.printNumber("SectionCount", COFFHeader->NumberOfSections);
-    W.printHex   ("TimeDateStamp", FormattedTime, COFFHeader->TimeDateStamp);
-    W.printHex   ("PointerToSymbolTable", COFFHeader->PointerToSymbolTable);
-    W.printNumber("SymbolCount", COFFHeader->NumberOfSymbols);
-    W.printNumber("OptionalHeaderSize", COFFHeader->SizeOfOptionalHeader);
-    W.printFlags ("Characteristics", COFFHeader->Characteristics,
+    W.printNumber("SectionCount", Obj->getNumberOfSections());
+    W.printHex   ("TimeDateStamp", FormattedTime, Obj->getTimeDateStamp());
+    W.printHex   ("PointerToSymbolTable", Obj->getPointerToSymbolTable());
+    W.printNumber("SymbolCount", Obj->getNumberOfSymbols());
+    W.printNumber("OptionalHeaderSize", Obj->getSizeOfOptionalHeader());
+    W.printFlags ("Characteristics", Obj->getCharacteristics(),
                     makeArrayRef(ImageFileCharacteristics));
   }
 
@@ -722,9 +718,9 @@
 void COFFDumper::printSymbol(const SymbolRef &Sym) {
   DictScope D(W, "Symbol");
 
-  const coff_symbol *Symbol = Obj->getCOFFSymbol(Sym);
+  COFFSymbolRef Symbol = Obj->getCOFFSymbol(Sym);
   const coff_section *Section;
-  if (std::error_code EC = Obj->getSection(Symbol->SectionNumber, Section)) {
+  if (std::error_code EC = Obj->getSection(Symbol.getSectionNumber(), Section)) {
     W.startLine() << "Invalid section number: " << EC.message() << "\n";
     W.flush();
     return;
@@ -739,19 +735,19 @@
     Obj->getSectionName(Section, SectionName);
 
   W.printString("Name", SymbolName);
-  W.printNumber("Value", Symbol->Value);
-  W.printNumber("Section", SectionName, Symbol->SectionNumber);
-  W.printEnum  ("BaseType", Symbol->getBaseType(), makeArrayRef(ImageSymType));
-  W.printEnum  ("ComplexType", Symbol->getComplexType(),
+  W.printNumber("Value", Symbol.getValue());
+  W.printNumber("Section", SectionName, Symbol.getSectionNumber());
+  W.printEnum  ("BaseType", Symbol.getBaseType(), makeArrayRef(ImageSymType));
+  W.printEnum  ("ComplexType", Symbol.getComplexType(),
                                                    makeArrayRef(ImageSymDType));
-  W.printEnum  ("StorageClass", Symbol->StorageClass,
+  W.printEnum  ("StorageClass", Symbol.getStorageClass(),
                                                    makeArrayRef(ImageSymClass));
-  W.printNumber("AuxSymbolCount", Symbol->NumberOfAuxSymbols);
+  W.printNumber("AuxSymbolCount", Symbol.getNumberOfAuxSymbols());
 
-  for (unsigned I = 0; I < Symbol->NumberOfAuxSymbols; ++I) {
-    if (Symbol->isFunctionDefinition()) {
+  for (uint8_t I = 0; I < Symbol.getNumberOfAuxSymbols(); ++I) {
+    if (Symbol.isFunctionDefinition()) {
       const coff_aux_function_definition *Aux;
-      if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))
+      if (error(getSymbolAuxData(Obj, Symbol, I, Aux)))
         break;
 
       DictScope AS(W, "AuxFunctionDef");
@@ -759,18 +755,16 @@
       W.printNumber("TotalSize", Aux->TotalSize);
       W.printHex("PointerToLineNumber", Aux->PointerToLinenumber);
       W.printHex("PointerToNextFunction", Aux->PointerToNextFunction);
-      W.printBinary("Unused", makeArrayRef(Aux->Unused));
 
-    } else if (Symbol->isWeakExternal()) {
+    } else if (Symbol.isWeakExternal()) {
       const coff_aux_weak_external *Aux;
-      if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))
+      if (error(getSymbolAuxData(Obj, Symbol, I, Aux)))
         break;
 
-      const coff_symbol *Linked;
+      ErrorOr<COFFSymbolRef> Linked = Obj->getSymbol(Aux->TagIndex);
       StringRef LinkedName;
-      std::error_code EC;
-      if ((EC = Obj->getSymbol(Aux->TagIndex, Linked)) ||
-          (EC = Obj->getSymbolName(Linked, LinkedName))) {
+      std::error_code EC = Linked.getError();
+      if (EC || (EC = Obj->getSymbolName(*Linked, LinkedName))) {
         LinkedName = "";
         error(EC);
       }
@@ -779,22 +773,21 @@
       W.printNumber("Linked", LinkedName, Aux->TagIndex);
       W.printEnum  ("Search", Aux->Characteristics,
                     makeArrayRef(WeakExternalCharacteristics));
-      W.printBinary("Unused", makeArrayRef(Aux->Unused));
 
-    } else if (Symbol->isFileRecord()) {
-      const coff_aux_file *Aux;
-      if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))
+    } else if (Symbol.isFileRecord()) {
+      const char *FileName;
+      if (error(getSymbolAuxData(Obj, Symbol, I, FileName)))
         break;
 
       DictScope AS(W, "AuxFileRecord");
 
-      StringRef Name(Aux->FileName,
-                     Symbol->NumberOfAuxSymbols * COFF::SymbolSize);
+      StringRef Name(FileName, Symbol.getNumberOfAuxSymbols() *
+                                   Obj->getSymbolTableEntrySize());
       W.printString("FileName", Name.rtrim(StringRef("\0", 1)));
       break;
-    } else if (Symbol->isSectionDefinition()) {
+    } else if (Symbol.isSectionDefinition()) {
       const coff_aux_section_definition *Aux;
-      if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))
+      if (error(getSymbolAuxData(Obj, Symbol, I, Aux)))
         break;
 
       DictScope AS(W, "AuxSectionDef");
@@ -804,7 +797,6 @@
       W.printHex("Checksum", Aux->CheckSum);
       W.printNumber("Number", Aux->Number);
       W.printEnum("Selection", Aux->Selection, makeArrayRef(ImageCOMDATSelect));
-      W.printBinary("Unused", makeArrayRef(Aux->Unused));
 
       if (Section && Section->Characteristics & COFF::IMAGE_SCN_LNK_COMDAT
           && Aux->Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
@@ -819,16 +811,16 @@
 
         W.printNumber("AssocSection", AssocName, Aux->Number);
       }
-    } else if (Symbol->isCLRToken()) {
+    } else if (Symbol.isCLRToken()) {
       const coff_aux_clr_token *Aux;
-      if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))
+      if (error(getSymbolAuxData(Obj, Symbol, I, Aux)))
         break;
 
-      const coff_symbol *ReferredSym;
+      ErrorOr<COFFSymbolRef> ReferredSym =
+          Obj->getSymbol(Aux->SymbolTableIndex);
       StringRef ReferredName;
-      std::error_code EC;
-      if ((EC = Obj->getSymbol(Aux->SymbolTableIndex, ReferredSym)) ||
-          (EC = Obj->getSymbolName(ReferredSym, ReferredName))) {
+      std::error_code EC = ReferredSym.getError();
+      if (EC || (EC = Obj->getSymbolName(*ReferredSym, ReferredName))) {
         ReferredName = "";
         error(EC);
       }
@@ -837,7 +829,6 @@
       W.printNumber("AuxType", Aux->AuxType);
       W.printNumber("Reserved", Aux->Reserved);
       W.printNumber("SymbolTableIndex", ReferredName, Aux->SymbolTableIndex);
-      W.printBinary("Unused", makeArrayRef(Aux->Unused));
 
     } else {
       W.startLine() << "<unhandled auxiliary record>\n";
@@ -846,12 +837,8 @@
 }
 
 void COFFDumper::printUnwindInfo() {
-  const coff_file_header *Header;
-  if (error(Obj->getCOFFHeader(Header)))
-    return;
-
   ListScope D(W, "UnwindInformation");
-  switch (Header->Machine) {
+  switch (Obj->getMachine()) {
   case COFF::IMAGE_FILE_MACHINE_AMD64: {
     Win64EH::Dumper Dumper(W);
     Win64EH::Dumper::SymbolResolver
@@ -870,7 +857,7 @@
     break;
   }
   default:
-    W.printEnum("unsupported Image Machine", Header->Machine,
+    W.printEnum("unsupported Image Machine", Obj->getMachine(),
                 makeArrayRef(ImageFileMachineType));
     break;
   }
Index: tools/obj2yaml/coff2yaml.cpp
===================================================================
--- tools/obj2yaml/coff2yaml.cpp
+++ tools/obj2yaml/coff2yaml.cpp
@@ -20,7 +20,7 @@
 class COFFDumper {
   const object::COFFObjectFile &Obj;
   COFFYAML::Object YAMLObj;
-  void dumpHeader(const object::coff_file_header *Header);
+  void dumpHeader();
   void dumpSections(unsigned numSections);
   void dumpSymbols(unsigned numSymbols);
 
@@ -31,22 +31,15 @@
 
 }
 
-static void check(std::error_code ec) {
-  if (ec)
-    report_fatal_error(ec.message());
-}
-
 COFFDumper::COFFDumper(const object::COFFObjectFile &Obj) : Obj(Obj) {
-  const object::coff_file_header *Header;
-  check(Obj.getCOFFHeader(Header));
-  dumpHeader(Header);
-  dumpSections(Header->NumberOfSections);
-  dumpSymbols(Header->NumberOfSymbols);
+  dumpHeader();
+  dumpSections(Obj.getNumberOfSections());
+  dumpSymbols(Obj.getNumberOfSymbols());
 }
 
-void COFFDumper::dumpHeader(const object::coff_file_header *Header) {
-  YAMLObj.Header.Machine = Header->Machine;
-  YAMLObj.Header.Characteristics = Header->Characteristics;
+void COFFDumper::dumpHeader() {
+  YAMLObj.Header.Machine = Obj.getMachine();
+  YAMLObj.Header.Characteristics = Obj.getCharacteristics();
 }
 
 void COFFDumper::dumpSections(unsigned NumSections) {
@@ -136,63 +129,64 @@
 void COFFDumper::dumpSymbols(unsigned NumSymbols) {
   std::vector<COFFYAML::Symbol> &Symbols = YAMLObj.Symbols;
   for (const auto &S : Obj.symbols()) {
-    const object::coff_symbol *Symbol = Obj.getCOFFSymbol(S);
+    object::COFFSymbolRef Symbol = Obj.getCOFFSymbol(S);
     COFFYAML::Symbol Sym;
     Obj.getSymbolName(Symbol, Sym.Name);
-    Sym.SimpleType = COFF::SymbolBaseType(Symbol->getBaseType());
-    Sym.ComplexType = COFF::SymbolComplexType(Symbol->getComplexType());
-    Sym.Header.StorageClass = Symbol->StorageClass;
-    Sym.Header.Value = Symbol->Value;
-    Sym.Header.SectionNumber = Symbol->SectionNumber;
-    Sym.Header.NumberOfAuxSymbols = Symbol->NumberOfAuxSymbols;
-
-    if (Symbol->NumberOfAuxSymbols > 0) {
+    Sym.SimpleType = COFF::SymbolBaseType(Symbol.getBaseType());
+    Sym.ComplexType = COFF::SymbolComplexType(Symbol.getComplexType());
+    Sym.Header.StorageClass = Symbol.getStorageClass();
+    Sym.Header.Value = Symbol.getValue();
+    Sym.Header.SectionNumber = Symbol.getSectionNumber();
+    Sym.Header.NumberOfAuxSymbols = Symbol.getNumberOfAuxSymbols();
+
+    if (Symbol.getNumberOfAuxSymbols() > 0) {
       ArrayRef<uint8_t> AuxData = Obj.getSymbolAuxData(Symbol);
-      if (Symbol->isFunctionDefinition()) {
+      if (Symbol.isFunctionDefinition()) {
         // This symbol represents a function definition.
-        assert(Symbol->NumberOfAuxSymbols == 1 &&
+        assert(Symbol.getNumberOfAuxSymbols() == 1 &&
                "Expected a single aux symbol to describe this function!");
 
         const object::coff_aux_function_definition *ObjFD =
             reinterpret_cast<const object::coff_aux_function_definition *>(
                 AuxData.data());
         dumpFunctionDefinition(&Sym, ObjFD);
-      } else if (Symbol->isFunctionLineInfo()) {
+      } else if (Symbol.isFunctionLineInfo()) {
         // This symbol describes function line number information.
-        assert(Symbol->NumberOfAuxSymbols == 1 &&
-               "Exepected a single aux symbol to describe this section!");
+        assert(Symbol.getNumberOfAuxSymbols() == 1 &&
+               "Expected a single aux symbol to describe this function!");
 
         const object::coff_aux_bf_and_ef_symbol *ObjBES =
             reinterpret_cast<const object::coff_aux_bf_and_ef_symbol *>(
                 AuxData.data());
         dumpbfAndEfLineInfo(&Sym, ObjBES);
-      } else if (Symbol->isWeakExternal()) {
+      } else if (Symbol.isWeakExternal()) {
         // This symbol represents a weak external definition.
-        assert(Symbol->NumberOfAuxSymbols == 1 &&
-               "Exepected a single aux symbol to describe this section!");
+        assert(Symbol.getNumberOfAuxSymbols() == 1 &&
+               "Expected a single aux symbol to describe this weak symbol!");
 
         const object::coff_aux_weak_external *ObjWE =
             reinterpret_cast<const object::coff_aux_weak_external *>(
                 AuxData.data());
         dumpWeakExternal(&Sym, ObjWE);
-      } else if (Symbol->isFileRecord()) {
+      } else if (Symbol.isFileRecord()) {
         // This symbol represents a file record.
         Sym.File = StringRef(reinterpret_cast<const char *>(AuxData.data()),
-                             Symbol->NumberOfAuxSymbols * COFF::SymbolSize)
+                             Symbol.getNumberOfAuxSymbols() *
+                                 Obj.getSymbolTableEntrySize())
                        .rtrim(StringRef("\0", /*length=*/1));
-      } else if (Symbol->isSectionDefinition()) {
+      } else if (Symbol.isSectionDefinition()) {
         // This symbol represents a section definition.
-        assert(Symbol->NumberOfAuxSymbols == 1 &&
+        assert(Symbol.getNumberOfAuxSymbols() == 1 &&
                "Expected a single aux symbol to describe this section!");
 
         const object::coff_aux_section_definition *ObjSD =
             reinterpret_cast<const object::coff_aux_section_definition *>(
                 AuxData.data());
         dumpSectionDefinition(&Sym, ObjSD);
-      } else if (Symbol->isCLRToken()) {
+      } else if (Symbol.isCLRToken()) {
         // This symbol represents a CLR token definition.
-        assert(Symbol->NumberOfAuxSymbols == 1 &&
-               "Expected a single aux symbol to describe this CLR Token");
+        assert(Symbol.getNumberOfAuxSymbols() == 1 &&
+               "Expected a single aux symbol to describe this CLR Token!");
 
         const object::coff_aux_clr_token *ObjCLRToken =
             reinterpret_cast<const object::coff_aux_clr_token *>(