Index: include/llvm/DebugInfo/DWARF/DWARFFormValue.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFFormValue.h
+++ include/llvm/DebugInfo/DWARF/DWARFFormValue.h
@@ -81,17 +81,79 @@
   Optional<uint64_t> getAsAddress() const;
   Optional<uint64_t> getAsSectionOffset() const;
   Optional<ArrayRef<uint8_t>> getAsBlock() const;
+  /// Get the fixed byte size for a given form.
+  ///
+  /// If the form always has a fixed valid byte size that doesn't depend on a
+  /// DWARFUnit, then an Optional with a value will be returned. If the form
+  /// can vary in size depending on the DWARFUnit (DWARF version, address byte
+  /// size, or DWARF 32/64) and the DWARFUnit is valid, then an Optional with a
+  /// valid value is returned. If the form is always encoded using a variable
+  /// length storage format (ULEB or SLEB numbers or blocks) or the size
+  /// depends on a DWARFUnit and the DWARFUnit is NULL, then None will be
+  /// returned.
+  /// \param Form The DWARF form to get the fixed byte size for
+  /// \param U The DWARFUnit that can be used to help determine the byte size.
+  ///
+  /// \returns Optional<uint8_t> value with the fixed byte size or None if
+  /// \p Form doesn't have a fixed byte size or a DWARFUnit wasn't supplied
+  /// and was needed to calculate the byte size.
+  static Optional<uint8_t> getFixedByteSize(dwarf::Form Form,
+                                            const DWARFUnit *U = nullptr);
+  /// Get the fixed byte size for a given form.
+  ///
+  /// If the form has a fixed byte size given a valid DWARF version and address
+  /// byte size, then an Optional with a valid value is returned. If the form
+  /// is always encoded using a variable length storage format (ULEB or SLEB
+  /// numbers or blocks) then None will be returned.
+  ///
+  /// \param Form DWARF form to get the fixed byte size for
+  /// \param Version DWARF version number.
+  /// \param AddrSize size of an address in bytes.
+  /// \param Format enum value from llvm::dwarf::DwarfFormat.
+  /// \returns Optional<uint8_t> value with the fixed byte size or None if
+  /// \p Form doesn't have a fixed byte size.
+  static Optional<uint8_t> getFixedByteSize(dwarf::Form Form, uint16_t Version,
+                                            uint8_t AddrSize,
+                                            llvm::dwarf::DwarfFormat Format);
 
+  /// Skip a form in \p debug_info_data at offset specified by \p offset_ptr.
+  ///
+  /// Skips the bytes for this form in the debug info and updates the offset.
+  ///
+  /// \param debug_info_data the .debug_info data to use to skip the value.
+  /// \param offset_ptr a reference to the offset that will be updated.
+  /// \param U the DWARFUnit to use when skipping the form in case the form
+  /// size differs according to data in the DWARFUnit.
+  /// \returns true on success, false if the form was not skipped.
   bool skipValue(DataExtractor debug_info_data, uint32_t *offset_ptr,
                  const DWARFUnit *U) const;
+  /// Skip a form in \p debug_info_data at offset specified by \p offset_ptr.
+  ///
+  /// Skips the bytes for this form in the debug info and updates the offset.
+  ///
+  /// \param form the DW_FORM enumeration that indicates the form to skip.
+  /// \param debug_info_data the .debug_info data to use to skip the value.
+  /// \param offset_ptr a reference to the offset that will be updated.
+  /// \param U the DWARFUnit to use when skipping the form in case the form
+  /// size differs according to data in the DWARFUnit.
+  /// \returns true on success, false if the form was not skipped.
   static bool skipValue(dwarf::Form form, DataExtractor debug_info_data,
-                        uint32_t *offset_ptr, const DWARFUnit *u);
+                        uint32_t *offset_ptr, const DWARFUnit *U);
+  /// Skip a form in \p debug_info_data at offset specified by \p offset_ptr.
+  ///
+  /// Skips the bytes for this form in the debug info and updates the offset.
+  ///
+  /// \param form the DW_FORM enumeration that indicates the form to skip.
+  /// \param debug_info_data the .debug_info data to use to skip the value.
+  /// \param offset_ptr a reference to the offset that will be updated.
+  /// \param Version DWARF version number.
+  /// \param AddrSize size of an address in bytes.
+  /// \param Format enum value from llvm::dwarf::DwarfFormat.
+  /// \returns true on success, false if the form was not skipped.
   static bool skipValue(dwarf::Form form, DataExtractor debug_info_data,
                         uint32_t *offset_ptr, uint16_t Version,
-                        uint8_t AddrSize);
+                        uint8_t AddrSize, llvm::dwarf::DwarfFormat Format);
 
-  static ArrayRef<uint8_t> getFixedFormSizes(uint8_t AddrSize,
-                                             uint16_t Version);
 private:
   void dumpString(raw_ostream &OS) const;
 };
Index: include/llvm/DebugInfo/DWARF/DWARFUnit.h
===================================================================
--- include/llvm/DebugInfo/DWARF/DWARFUnit.h
+++ include/llvm/DebugInfo/DWARF/DWARFUnit.h
@@ -191,14 +191,26 @@
   uint32_t getNextUnitOffset() const { return Offset + Length + 4; }
   uint32_t getLength() const { return Length; }
   uint16_t getVersion() const { return Version; }
+  dwarf::DwarfFormat getFormat() const {
+    return dwarf::DwarfFormat::DWARF32; // FIXME: Support DWARF64.
+  }
   const DWARFAbbreviationDeclarationSet *getAbbreviations() const {
     return Abbrevs;
   }
   uint8_t getAddressByteSize() const { return AddrSize; }
   uint8_t getRefAddrByteSize() const {
-    // FIXME: Support DWARF64.
-    return (Version == 2) ? AddrSize : 4;
+    if (Version == 2)
+      return AddrSize;
+    return getDwarfOffsetByteSize();
   }
+  uint8_t getDwarfOffsetByteSize() const {
+    switch (getFormat()) {
+    case dwarf::DwarfFormat::DWARF32:
+      return 4;
+    case dwarf::DwarfFormat::DWARF64:
+      return 8;
+    }
+  }
   uint64_t getBaseAddress() const { return BaseAddr; }
 
   void setBaseAddress(uint64_t base_addr) {
Index: include/llvm/Support/Dwarf.h
===================================================================
--- include/llvm/Support/Dwarf.h
+++ include/llvm/Support/Dwarf.h
@@ -433,6 +433,9 @@
   };
 };
 
+/// Constants that define the DWARF format as 32 or 64 bit.
+enum DwarfFormat { DWARF32, DWARF64 };
+
 } // End of namespace dwarf
 
 } // End of namespace llvm
Index: lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
+++ lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
@@ -202,18 +202,13 @@
     *OffsetPtr = Offset;
     return false;
   }
-  ArrayRef<uint8_t> FixedFormSizes = DWARFFormValue::getFixedFormSizes(
-      U->getAddressByteSize(), U->getVersion());
-  assert(FixedFormSizes.size() > 0);
 
   // Skip all data in the .debug_info for the attributes
   for (const auto &AttrSpec : AbbrevDecl->attributes()) {
     auto Form = AttrSpec.Form;
 
-    uint8_t FixedFormSize =
-        (Form < FixedFormSizes.size()) ? FixedFormSizes[Form] : 0;
-    if (FixedFormSize)
-      *OffsetPtr += FixedFormSize;
+    if (Optional<uint8_t> FixedSize = DWARFFormValue::getFixedByteSize(Form, U))
+      *OffsetPtr += *FixedSize;
     else if (!DWARFFormValue::skipValue(Form, DebugInfoData, OffsetPtr, U)) {
       // Restore the original offset.
       *OffsetPtr = Offset;
Index: lib/DebugInfo/DWARF/DWARFFormValue.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -23,60 +23,6 @@
 using namespace dwarf;
 using namespace syntax;
 
-namespace {
-uint8_t getRefAddrSize(uint8_t AddrSize, uint16_t Version) {
-  // FIXME: Support DWARF64.
-  return (Version == 2) ? AddrSize : 4;
-}
-
-template <uint8_t AddrSize, uint8_t RefAddrSize>
-ArrayRef<uint8_t> makeFixedFormSizesArrayRef() {
-  static const uint8_t sizes[] = {
-    0,           // 0x00 unused
-    AddrSize,    // 0x01 DW_FORM_addr
-    0,           // 0x02 unused
-    0,           // 0x03 DW_FORM_block2
-    0,           // 0x04 DW_FORM_block4
-    2,           // 0x05 DW_FORM_data2
-    4,           // 0x06 DW_FORM_data4
-    8,           // 0x07 DW_FORM_data8
-    0,           // 0x08 DW_FORM_string
-    0,           // 0x09 DW_FORM_block
-    0,           // 0x0a DW_FORM_block1
-    1,           // 0x0b DW_FORM_data1
-    1,           // 0x0c DW_FORM_flag
-    0,           // 0x0d DW_FORM_sdata
-    4,           // 0x0e DW_FORM_strp
-    0,           // 0x0f DW_FORM_udata
-    RefAddrSize, // 0x10 DW_FORM_ref_addr
-    1,           // 0x11 DW_FORM_ref1
-    2,           // 0x12 DW_FORM_ref2
-    4,           // 0x13 DW_FORM_ref4
-    8,           // 0x14 DW_FORM_ref8
-    0,           // 0x15 DW_FORM_ref_udata
-    0,           // 0x16 DW_FORM_indirect
-    4,           // 0x17 DW_FORM_sec_offset
-    0,           // 0x18 DW_FORM_exprloc
-    0,           // 0x19 DW_FORM_flag_present
-  };
-  return makeArrayRef(sizes);
-}
-}
-
-ArrayRef<uint8_t> DWARFFormValue::getFixedFormSizes(uint8_t AddrSize,
-                                                    uint16_t Version) {
-  uint8_t RefAddrSize = getRefAddrSize(AddrSize, Version);
-  if (AddrSize == 4 && RefAddrSize == 4)
-    return makeFixedFormSizesArrayRef<4, 4>();
-  if (AddrSize == 4 && RefAddrSize == 8)
-    return makeFixedFormSizesArrayRef<4, 8>();
-  if (AddrSize == 8 && RefAddrSize == 4)
-    return makeFixedFormSizesArrayRef<8, 4>();
-  if (AddrSize == 8 && RefAddrSize == 8)
-    return makeFixedFormSizesArrayRef<8, 8>();
-  return None;
-}
-
 static const DWARFFormValue::FormClass DWARF4FormClasses[] = {
   DWARFFormValue::FC_Unknown,       // 0x0
   DWARFFormValue::FC_Address,       // 0x01 DW_FORM_addr
@@ -108,6 +54,214 @@
   DWARFFormValue::FC_Flag,          // 0x19 DW_FORM_flag_present
 };
 
+namespace {
+
+/// A helper class that can be used in DWARFFormValue.cpp functions that need
+/// to know the byte size of DW_FORM values that vary in size depending on the
+/// DWARF version, address byte size, or DWARF32 or DWARF64.
+class FormSizeHelper {
+  uint16_t Version;
+  uint8_t AddrSize;
+  llvm::dwarf::DwarfFormat Format;
+
+public:
+  FormSizeHelper(uint16_t V, uint8_t A, llvm::dwarf::DwarfFormat F)
+  : Version(V), AddrSize(A), Format(F) {}
+  uint8_t getAddressByteSize() const { return AddrSize; }
+  uint8_t getRefAddrByteSize() const {
+    if (Version == 2)
+      return AddrSize;
+    return getDwarfOffsetByteSize();
+  }
+  uint8_t getDwarfOffsetByteSize() const {
+    switch (Format) {
+      case dwarf::DwarfFormat::DWARF32:
+        return 4;
+      case dwarf::DwarfFormat::DWARF64:
+        return 8;
+    }
+    llvm_unreachable("Invalid Format value");
+  }
+};
+
+} // end anonymous namespace
+
+template <class T>
+static Optional<uint8_t> getFixedByteSize(dwarf::Form Form, const T *U) {
+  switch (Form) {
+    case DW_FORM_addr:
+      if (U)
+        return U->getAddressByteSize();
+      return None;
+
+    case DW_FORM_block:          // ULEB128 length L followed by L bytes.
+    case DW_FORM_block1:         // 1 byte length L followed by L bytes.
+    case DW_FORM_block2:         // 2 byte length L followed by L bytes.
+    case DW_FORM_block4:         // 4 byte length L followed by L bytes.
+    case DW_FORM_string:         // C-string with null terminator.
+    case DW_FORM_sdata:          // SLEB128.
+    case DW_FORM_udata:          // ULEB128.
+    case DW_FORM_ref_udata:      // ULEB128.
+    case DW_FORM_indirect:       // ULEB128.
+    case DW_FORM_exprloc:        // ULEB128 length L followed by L bytes.
+    case DW_FORM_strx:           // ULEB128.
+    case DW_FORM_addrx:          // ULEB128.
+    case DW_FORM_loclistx:       // ULEB128.
+    case DW_FORM_rnglistx:       // ULEB128.
+    case DW_FORM_GNU_addr_index: // ULEB128.
+    case DW_FORM_GNU_str_index:  // ULEB128.
+      return None;
+
+    case DW_FORM_ref_addr:
+      if (U)
+        return U->getRefAddrByteSize();
+      return None;
+
+    case DW_FORM_flag:
+    case DW_FORM_data1:
+    case DW_FORM_ref1:
+      return 1;
+
+    case DW_FORM_data2:
+    case DW_FORM_ref2:
+      return 2;
+
+    case DW_FORM_data4:
+    case DW_FORM_ref4:
+    case DW_FORM_strp:
+      return 4;
+
+    case DW_FORM_GNU_ref_alt:
+    case DW_FORM_GNU_strp_alt:
+    case DW_FORM_line_strp:
+    case DW_FORM_sec_offset:
+    case DW_FORM_strp_sup:
+    case DW_FORM_ref_sup:
+      if (U)
+        return U->getDwarfOffsetByteSize();
+      return None;
+
+    case DW_FORM_data8:
+    case DW_FORM_ref8:
+    case DW_FORM_ref_sig8:
+      return 8;
+
+    case DW_FORM_flag_present:
+      return 0;
+
+    case DW_FORM_data16:
+      return 16;
+
+    case DW_FORM_implicit_const:
+      // The implicit value is stored in the abbreviation as a ULEB128, any
+      // there no data in debug info.
+      return 0;
+
+    default:
+      llvm_unreachable("Handle this form in this switch statement");
+  }
+  return None;
+}
+
+template <class T>
+static bool skipFormValue(dwarf::Form Form, const DataExtractor &DebugInfoData,
+                          uint32_t *OffsetPtr, const T *U) {
+  bool Indirect = false;
+  do {
+    switch (Form) {
+        // Blocks if inlined data that have a length field and the data bytes
+        // inlined in the .debug_info.
+      case DW_FORM_exprloc:
+      case DW_FORM_block: {
+        uint64_t size = DebugInfoData.getULEB128(OffsetPtr);
+        *OffsetPtr += size;
+        return true;
+      }
+      case DW_FORM_block1: {
+        uint8_t size = DebugInfoData.getU8(OffsetPtr);
+        *OffsetPtr += size;
+        return true;
+      }
+      case DW_FORM_block2: {
+        uint16_t size = DebugInfoData.getU16(OffsetPtr);
+        *OffsetPtr += size;
+        return true;
+      }
+      case DW_FORM_block4: {
+        uint32_t size = DebugInfoData.getU32(OffsetPtr);
+        *OffsetPtr += size;
+        return true;
+      }
+
+        // Inlined NULL terminated C-strings.
+      case DW_FORM_string:
+        DebugInfoData.getCStr(OffsetPtr);
+        return true;
+
+      case DW_FORM_addr:
+      case DW_FORM_ref_addr:
+      case DW_FORM_flag_present:
+      case DW_FORM_data1:
+      case DW_FORM_data2:
+      case DW_FORM_data4:
+      case DW_FORM_data8:
+      case DW_FORM_flag:
+      case DW_FORM_ref1:
+      case DW_FORM_ref2:
+      case DW_FORM_ref4:
+      case DW_FORM_ref8:
+      case DW_FORM_ref_sig8:
+      case DW_FORM_sec_offset:
+      case DW_FORM_strp:
+      case DW_FORM_GNU_ref_alt:
+      case DW_FORM_GNU_strp_alt:
+        if (Optional<uint8_t> FixedSize = ::getFixedByteSize(Form, U)) {
+          *OffsetPtr += *FixedSize;
+          return true;
+        }
+        return false;
+
+        // signed or unsigned LEB 128 values.
+      case DW_FORM_sdata:
+        DebugInfoData.getSLEB128(OffsetPtr);
+        return true;
+
+      case DW_FORM_udata:
+      case DW_FORM_ref_udata:
+      case DW_FORM_strx:
+      case DW_FORM_addrx:
+      case DW_FORM_loclistx:
+      case DW_FORM_rnglistx:
+      case DW_FORM_GNU_addr_index:
+      case DW_FORM_GNU_str_index:
+        DebugInfoData.getULEB128(OffsetPtr);
+        return true;
+        
+      case DW_FORM_indirect:
+        Indirect = true;
+        Form = static_cast<dwarf::Form>(DebugInfoData.getULEB128(OffsetPtr));
+        break;
+        
+      default:
+        return false;
+    }
+  } while (Indirect);
+  return true;
+}
+
+Optional<uint8_t> DWARFFormValue::getFixedByteSize(dwarf::Form Form,
+                                                   const DWARFUnit *U) {
+  return ::getFixedByteSize(Form, U);
+}
+
+Optional<uint8_t>
+DWARFFormValue::getFixedByteSize(dwarf::Form Form, uint16_t Version,
+                                 uint8_t AddrSize,
+                                 llvm::dwarf::DwarfFormat Format) {
+  FormSizeHelper FSH(Version, AddrSize, Format);
+  return ::getFixedByteSize(Form, &FSH);
+}
+
 bool DWARFFormValue::isFormClass(DWARFFormValue::FormClass FC) const {
   // First, check DWARF4 form classes.
   if (Form < makeArrayRef(DWARF4FormClasses).size() &&
@@ -155,8 +309,7 @@
               : U->getRefAddrByteSize();
       RelocAddrMap::const_iterator AI = U->getRelocMap()->find(*offset_ptr);
       if (AI != U->getRelocMap()->end()) {
-        const std::pair<uint8_t, int64_t> &R = AI->second;
-        Value.uval = data.getUnsigned(offset_ptr, AddrSize) + R.second;
+        Value.uval = data.getUnsigned(offset_ptr, AddrSize) + AI->second.second;
       } else
         Value.uval = data.getUnsigned(offset_ptr, AddrSize);
       break;
@@ -188,7 +341,8 @@
       Value.uval = data.getU16(offset_ptr);
       break;
     case DW_FORM_data4:
-    case DW_FORM_ref4: {
+    case DW_FORM_ref4:
+    case DW_FORM_strp: {
       Value.uval = data.getU32(offset_ptr);
       if (!U)
         break;
@@ -216,15 +370,16 @@
       indirect = true;
       break;
     case DW_FORM_sec_offset:
-    case DW_FORM_strp:
     case DW_FORM_GNU_ref_alt:
-    case DW_FORM_GNU_strp_alt: {
-      // FIXME: This is 64-bit for DWARF64.
-      Value.uval = data.getU32(offset_ptr);
+    case DW_FORM_GNU_strp_alt:
+    case DW_FORM_line_strp:
+    case DW_FORM_strp_sup:
+    case DW_FORM_ref_sup: {
       if (!U)
-        break;
-      RelocAddrMap::const_iterator AI =
-          U->getRelocMap()->find(*offset_ptr - 4);
+        return false;
+      RelocAddrMap::const_iterator AI = U->getRelocMap()->find(*offset_ptr);
+      uint8_t Size = U->getDwarfOffsetByteSize();
+      Value.uval = data.getUnsigned(offset_ptr, Size);
       if (AI != U->getRelocMap()->end())
         Value.uval += AI->second.second;
       break;
@@ -256,120 +411,22 @@
   return true;
 }
 
-bool
-DWARFFormValue::skipValue(DataExtractor debug_info_data, uint32_t* offset_ptr,
-                          const DWARFUnit *U) const {
-  return DWARFFormValue::skipValue(Form, debug_info_data, offset_ptr, U);
+bool DWARFFormValue::skipValue(DataExtractor DebugInfoData,
+                               uint32_t *offset_ptr, const DWARFUnit *U) const {
+  return DWARFFormValue::skipValue(Form, DebugInfoData, offset_ptr, U);
 }
 
-bool
-DWARFFormValue::skipValue(dwarf::Form form, DataExtractor debug_info_data,
-                          uint32_t *offset_ptr, const DWARFUnit *cu) {
-  return skipValue(form, debug_info_data, offset_ptr, cu->getVersion(),
-                   cu->getAddressByteSize());
+bool DWARFFormValue::skipValue(dwarf::Form form, DataExtractor DebugInfoData,
+                               uint32_t *offset_ptr, const DWARFUnit *U) {
+  return skipFormValue(form, DebugInfoData, offset_ptr, U);
 }
-bool 
-DWARFFormValue::skipValue(dwarf::Form form, DataExtractor debug_info_data,
-                          uint32_t *offset_ptr, uint16_t Version,
-                          uint8_t AddrSize) {
-  bool indirect = false;
-  do {
-    switch (form) {
-    // Blocks if inlined data that have a length field and the data bytes
-    // inlined in the .debug_info
-    case DW_FORM_exprloc:
-    case DW_FORM_block: {
-      uint64_t size = debug_info_data.getULEB128(offset_ptr);
-      *offset_ptr += size;
-      return true;
-    }
-    case DW_FORM_block1: {
-      uint8_t size = debug_info_data.getU8(offset_ptr);
-      *offset_ptr += size;
-      return true;
-    }
-    case DW_FORM_block2: {
-      uint16_t size = debug_info_data.getU16(offset_ptr);
-      *offset_ptr += size;
-      return true;
-    }
-    case DW_FORM_block4: {
-      uint32_t size = debug_info_data.getU32(offset_ptr);
-      *offset_ptr += size;
-      return true;
-    }
 
-    // Inlined NULL terminated C-strings
-    case DW_FORM_string:
-      debug_info_data.getCStr(offset_ptr);
-      return true;
-
-    // Compile unit address sized values
-    case DW_FORM_addr:
-      *offset_ptr += AddrSize;
-      return true;
-    case DW_FORM_ref_addr:
-      *offset_ptr += getRefAddrSize(AddrSize, Version);
-      return true;
-
-    // 0 byte values - implied from the form.
-    case DW_FORM_flag_present:
-      return true;
-
-    // 1 byte values
-    case DW_FORM_data1:
-    case DW_FORM_flag:
-    case DW_FORM_ref1:
-      *offset_ptr += 1;
-      return true;
-
-    // 2 byte values
-    case DW_FORM_data2:
-    case DW_FORM_ref2:
-      *offset_ptr += 2;
-      return true;
-
-    // 4 byte values
-    case DW_FORM_data4:
-    case DW_FORM_ref4:
-      *offset_ptr += 4;
-      return true;
-
-    // 8 byte values
-    case DW_FORM_data8:
-    case DW_FORM_ref8:
-    case DW_FORM_ref_sig8:
-      *offset_ptr += 8;
-      return true;
-
-    // signed or unsigned LEB 128 values
-    //  case DW_FORM_APPLE_db_str:
-    case DW_FORM_sdata:
-    case DW_FORM_udata:
-    case DW_FORM_ref_udata:
-    case DW_FORM_GNU_str_index:
-    case DW_FORM_GNU_addr_index:
-      debug_info_data.getULEB128(offset_ptr);
-      return true;
-
-    case DW_FORM_indirect:
-      indirect = true;
-      form = static_cast<dwarf::Form>(debug_info_data.getULEB128(offset_ptr));
-      break;
-
-    // FIXME: 4 for DWARF32, 8 for DWARF64.
-    case DW_FORM_sec_offset:
-    case DW_FORM_strp:
-    case DW_FORM_GNU_ref_alt:
-    case DW_FORM_GNU_strp_alt:
-      *offset_ptr += 4;
-      return true;
-
-    default:
-      return false;
-    }
-  } while (indirect);
-  return true;
+bool DWARFFormValue::skipValue(dwarf::Form form, DataExtractor DebugInfoData,
+                               uint32_t *offset_ptr, uint16_t Version,
+                               uint8_t AddrSize,
+                               llvm::dwarf::DwarfFormat Format) {
+  FormSizeHelper FSH(Version, AddrSize, Format);
+  return skipFormValue(form, DebugInfoData, offset_ptr, &FSH);
 }
 
 void
@@ -556,8 +613,9 @@
       return None;
     return Value.uval + U->getOffset();
   case DW_FORM_ref_addr:
+  case DW_FORM_ref_sig8:
+  case DW_FORM_GNU_ref_alt:
     return Value.uval;
-  // FIXME: Add proper support for DW_FORM_ref_sig8 and DW_FORM_GNU_ref_alt.
   default:
     return None;
   }
Index: tools/llvm-dwp/llvm-dwp.cpp
===================================================================
--- tools/llvm-dwp/llvm-dwp.cpp
+++ tools/llvm-dwp/llvm-dwp.cpp
@@ -133,7 +133,14 @@
                                                          StringRef Str) {
   uint32_t Offset = 0;
   DataExtractor InfoData(Info, true, 0);
-  InfoData.getU32(&Offset); // Length
+  dwarf::DwarfFormat Format = dwarf::DwarfFormat::DWARF32;
+  uint64_t Length = InfoData.getU32(&Offset);
+  // If the length is 0xffffffff, then this indictes that this is a DWARF 64
+  // stream and the length is actually encoded into a 64 bit value that follows.
+  if (Length == 0xffffffffU) {
+    Format = dwarf::DwarfFormat::DWARF64;
+    Length = InfoData.getU64(&Offset);
+  }
   uint16_t Version = InfoData.getU16(&Offset);
   InfoData.getU32(&Offset); // Abbrev offset (should be zero)
   uint8_t AddrSize = InfoData.getU8(&Offset);
@@ -174,7 +181,8 @@
       ID.Signature = InfoData.getU64(&Offset);
       break;
     default:
-      DWARFFormValue::skipValue(Form, InfoData, &Offset, Version, AddrSize);
+      DWARFFormValue::skipValue(Form, InfoData, &Offset, Version, AddrSize,
+                                Format);
     }
   }
   return ID;
Index: unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
===================================================================
--- unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
+++ unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
@@ -21,16 +21,47 @@
 namespace {
 
 TEST(DWARFFormValue, FixedFormSizes) {
-  // Size of DW_FORM_addr and DW_FORM_ref_addr are equal in DWARF2,
-  // DW_FORM_ref_addr is always 4 bytes in DWARF32 starting from DWARF3.
-  ArrayRef<uint8_t> sizes = DWARFFormValue::getFixedFormSizes(4, 2);
-  EXPECT_EQ(sizes[DW_FORM_addr], sizes[DW_FORM_ref_addr]);
-  sizes = DWARFFormValue::getFixedFormSizes(8, 2);
-  EXPECT_EQ(sizes[DW_FORM_addr], sizes[DW_FORM_ref_addr]);
-  sizes = DWARFFormValue::getFixedFormSizes(8, 3);
-  EXPECT_EQ(4, sizes[DW_FORM_ref_addr]);
-  // Check that we don't have fixed form sizes for weird address sizes.
-  EXPECT_EQ(0U, DWARFFormValue::getFixedFormSizes(16, 2).size());
+  Optional<uint8_t> RefSize;
+  Optional<uint8_t> AddrSize;
+  // Test 32 bit DWARF version 2 with 4 byte addresses.
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 2, 4, DWARF32);
+  AddrSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 2, 4, DWARF32);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_TRUE(AddrSize.hasValue());
+  EXPECT_EQ(*RefSize, *AddrSize);
+
+  // Test 32 bit DWARF version 2 with 8 byte addresses.
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 2, 8, DWARF32);
+  AddrSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 2, 8, DWARF32);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_TRUE(AddrSize.hasValue());
+  EXPECT_EQ(*RefSize, *AddrSize);
+
+  // DW_FORM_ref_addr is 4 bytes in DWARF 32 in DWARF version 3 and beyond.
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 3, 4, DWARF32);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 4);
+
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 4, 4, DWARF32);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 4);
+
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 5, 4, DWARF32);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 4);
+
+  // DW_FORM_ref_addr is 8 bytes in DWARF 64 in DWARF version 3 and beyond.
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 3, 8, DWARF64);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 8);
+
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 4, 8, DWARF64);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 8);
+
+  RefSize = DWARFFormValue::getFixedByteSize(DW_FORM_ref_addr, 5, 8, DWARF64);
+  EXPECT_TRUE(RefSize.hasValue());
+  EXPECT_EQ(*RefSize, 8);
 }
 
 bool isFormClass(dwarf::Form Form, DWARFFormValue::FormClass FC) {