diff --git a/lldb/include/lldb/Core/dwarf.h b/lldb/include/lldb/Core/dwarf.h
--- a/lldb/include/lldb/Core/dwarf.h
+++ b/lldb/include/lldb/Core/dwarf.h
@@ -30,11 +30,12 @@
                             // any addresses in the compile units that get
                             // parsed
 
-typedef uint32_t dw_offset_t; // Dwarf Debug Information Entry offset for any
+typedef uint64_t dw_offset_t; // Dwarf Debug Information Entry offset for any
                               // offset into the file
 
 /* Constants */
-#define DW_INVALID_OFFSET (~(dw_offset_t)0)
+#define DW_DIE_OFFSET_MAX_BITSIZE 40
+#define DW_INVALID_OFFSET (((uint64_t)1u << DW_DIE_OFFSET_MAX_BITSIZE) - 1)
 #define DW_INVALID_INDEX 0xFFFFFFFFul
 
 // #define DW_ADDR_none 0x0
diff --git a/lldb/include/lldb/Symbol/DWARFCallFrameInfo.h b/lldb/include/lldb/Symbol/DWARFCallFrameInfo.h
--- a/lldb/include/lldb/Symbol/DWARFCallFrameInfo.h
+++ b/lldb/include/lldb/Symbol/DWARFCallFrameInfo.h
@@ -128,7 +128,7 @@
 
   void GetFDEIndex();
 
-  bool FDEToUnwindPlan(uint32_t offset, Address startaddr,
+  bool FDEToUnwindPlan(dw_offset_t offset, Address startaddr,
                        UnwindPlan &unwind_plan);
 
   const CIE *GetCIE(dw_offset_t cie_offset);
@@ -159,7 +159,7 @@
   Type m_type;
 
   CIESP
-  ParseCIE(const uint32_t cie_offset);
+  ParseCIE(const dw_offset_t cie_offset);
 
   lldb::RegisterKind GetRegisterKind() const {
     return m_type == EH ? lldb::eRegisterKindEHFrame : lldb::eRegisterKindDWARF;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
@@ -80,7 +80,6 @@
   if (!m_apple_names_up)
     return;
 
-  lldbassert(!cu.GetSymbolFileDWARF().GetDwoNum());
   const DWARFUnit &non_skeleton_cu = cu.GetNonSkeletonUnit();
   DWARFMappedHash::DIEInfoArray hash_data;
   m_apple_names_up->AppendAllDIEsInRange(non_skeleton_cu.GetOffset(),
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
@@ -10,15 +10,17 @@
 #define LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DIEREF_H
 
 #include "lldb/Core/dwarf.h"
-#include "llvm/Support/FormatProviders.h"
+#include "lldb/Utility/LLDBAssert.h"
 #include <cassert>
 #include <optional>
-#include <vector>
 
 /// Identifies a DWARF debug info entry within a given Module. It contains three
 /// "coordinates":
-/// - dwo_num: identifies the dwo file in the Module. If this field is not set,
-///   the DIERef references the main file.
+/// - file_index: identifies the separate stand alone debug info file
+///   that is referred to by the main debug info file. This will be the
+///   index of a DWO file for fission, or the .o file on mac when not
+///   using a dSYM file. If this field is not set, then this references
+///   a DIE inside the original object file.
 /// - section: identifies the section of the debug info entry in the given file:
 ///   debug_info or debug_types.
 /// - die_offset: The offset of the debug info entry as an absolute offset from
@@ -26,17 +28,35 @@
 class DIERef {
 public:
   enum Section : uint8_t { DebugInfo, DebugTypes };
-
-  DIERef(std::optional<uint32_t> dwo_num, Section section,
+  DIERef(std::optional<uint32_t> file_index, Section section,
          dw_offset_t die_offset)
-      : m_dwo_num(dwo_num.value_or(0)), m_dwo_num_valid(bool(dwo_num)),
-        m_section(section), m_die_offset(die_offset) {
-    assert(this->dwo_num() == dwo_num && "Dwo number out of range?");
+      : m_die_offset(die_offset), m_file_index(file_index.value_or(0)),
+        m_file_index_valid(file_index ? true : false), m_section(section) {
+    assert(this->file_index() == file_index && "File Index is out of range?");
+  }
+
+  explicit DIERef(lldb::user_id_t uid) {
+    m_die_offset = uid & k_die_offset_mask;
+    m_file_index_valid = (uid & k_file_index_valid_bit) != 0;
+    m_file_index = m_file_index_valid
+                       ? (uid >> k_die_offset_bit_size) & k_file_index_mask
+                       : 0;
+    m_section =
+        (uid & k_section_bit) != 0 ? Section::DebugTypes : Section::DebugInfo;
+  }
+
+  lldb::user_id_t get_id() const {
+    if (m_die_offset == k_die_offset_mask)
+      return LLDB_INVALID_UID;
+
+    return lldb::user_id_t(file_index().value_or(0)) << k_die_offset_bit_size |
+           die_offset() | (m_file_index_valid ? k_file_index_valid_bit : 0) |
+           (section() == Section::DebugTypes ? k_section_bit : 0);
   }
 
-  std::optional<uint32_t> dwo_num() const {
-    if (m_dwo_num_valid)
-      return m_dwo_num;
+  std::optional<uint32_t> file_index() const {
+    if (m_file_index_valid)
+      return m_file_index;
     return std::nullopt;
   }
 
@@ -45,17 +65,17 @@
   dw_offset_t die_offset() const { return m_die_offset; }
 
   bool operator<(DIERef other) const {
-    if (m_dwo_num_valid != other.m_dwo_num_valid)
-      return m_dwo_num_valid < other.m_dwo_num_valid;
-    if (m_dwo_num_valid && (m_dwo_num != other.m_dwo_num))
-      return m_dwo_num < other.m_dwo_num;
+    if (m_file_index_valid != other.m_file_index_valid)
+      return m_file_index_valid < other.m_file_index_valid;
+    if (m_file_index_valid && (m_file_index != other.m_file_index))
+      return m_file_index < other.m_file_index;
     if (m_section != other.m_section)
       return m_section < other.m_section;
     return m_die_offset < other.m_die_offset;
   }
 
   bool operator==(const DIERef &rhs) const {
-    return dwo_num() == rhs.dwo_num() && m_section == rhs.m_section &&
+    return file_index() == rhs.file_index() && m_section == rhs.m_section &&
            m_die_offset == rhs.m_die_offset;
   }
 
@@ -85,11 +105,28 @@
   ///
   void Encode(lldb_private::DataEncoder &encoder) const;
 
+  static constexpr uint64_t k_die_offset_bit_size = DW_DIE_OFFSET_MAX_BITSIZE;
+  static constexpr uint64_t k_file_index_bit_size =
+      64 - DW_DIE_OFFSET_MAX_BITSIZE - /* size of control bits */ 2;
+
+  static constexpr uint64_t k_file_index_valid_bit =
+      (1ull << (k_file_index_bit_size + k_die_offset_bit_size));
+  static constexpr uint64_t k_section_bit =
+      (1ull << (k_file_index_bit_size + k_die_offset_bit_size + 1));
+  static constexpr uint64_t
+      k_file_index_mask = (~0ull) >> (64 - k_file_index_bit_size); // 0x3fffff;
+  static constexpr uint64_t k_die_offset_mask = (~0ull) >>
+                                                (64 - k_die_offset_bit_size);
+
 private:
-  uint32_t m_dwo_num : 30;
-  uint32_t m_dwo_num_valid : 1;
-  uint32_t m_section : 1;
-  dw_offset_t m_die_offset;
+  // Allow 2TB of .debug_info/.debug_types offset
+  dw_offset_t m_die_offset : k_die_offset_bit_size;
+  // Used for DWO index or for .o file index on mac
+  dw_offset_t m_file_index : k_file_index_bit_size;
+  // Set to 1 if m_file_index is a DWO number
+  dw_offset_t m_file_index_valid : 1;
+  // Set to 0 for .debug_info 1 for .debug_types,
+  dw_offset_t m_section : 1;
 };
 static_assert(sizeof(DIERef) == 8);
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.cpp
@@ -17,40 +17,22 @@
 
 void llvm::format_provider<DIERef>::format(const DIERef &ref, raw_ostream &OS,
                                            StringRef Style) {
-  if (ref.dwo_num())
-    OS << format_hex_no_prefix(*ref.dwo_num(), 8) << "/";
+  if (ref.file_index())
+    OS << format_hex_no_prefix(*ref.file_index(), 8) << "/";
   OS << (ref.section() == DIERef::DebugInfo ? "INFO" : "TYPE");
   OS << "/" << format_hex_no_prefix(ref.die_offset(), 8);
 }
 
-constexpr uint32_t k_dwo_num_mask = 0x3FFFFFFF;
-constexpr uint32_t k_dwo_num_valid_bitmask = (1u << 30);
-constexpr uint32_t k_section_bitmask = (1u << 31);
-
 std::optional<DIERef> DIERef::Decode(const DataExtractor &data,
                                      lldb::offset_t *offset_ptr) {
-  const uint32_t bitfield_storage = data.GetU32(offset_ptr);
-  uint32_t dwo_num = bitfield_storage & k_dwo_num_mask;
-  bool dwo_num_valid = (bitfield_storage & (k_dwo_num_valid_bitmask)) != 0;
-  Section section = (Section)((bitfield_storage & (k_section_bitmask)) != 0);
+  DIERef die_ref(data.GetU64(offset_ptr));
+
   // DIE offsets can't be zero and if we fail to decode something from data,
   // it will return 0
-  dw_offset_t die_offset = data.GetU32(offset_ptr);
-  if (die_offset == 0)
+  if (!die_ref.die_offset())
     return std::nullopt;
-  if (dwo_num_valid)
-    return DIERef(dwo_num, section, die_offset);
-  else
-    return DIERef(std::nullopt, section, die_offset);
-}
 
-void DIERef::Encode(DataEncoder &encoder) const {
-  uint32_t bitfield_storage = m_dwo_num;
-  if (m_dwo_num_valid)
-    bitfield_storage |= k_dwo_num_valid_bitmask;
-  if (m_section)
-    bitfield_storage |= k_section_bitmask;
-  encoder.AppendU32(bitfield_storage);
-  static_assert(sizeof(m_die_offset) == 4, "m_die_offset must be 4 bytes");
-  encoder.AppendU32(m_die_offset);
+  return die_ref;
 }
+
+void DIERef::Encode(DataEncoder &encoder) const { encoder.AppendU64(get_id()); }
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -731,10 +731,10 @@
     }
   }
 
-  type_sp = dwarf->MakeType(
-      die.GetID(), attrs.name, attrs.byte_size, nullptr,
-      dwarf->GetUID(attrs.type.Reference()), encoding_data_type, &attrs.decl,
-      clang_type, resolve_state, TypePayloadClang(GetOwningClangModule(die)));
+  type_sp = dwarf->MakeType(die.GetID(), attrs.name, attrs.byte_size, nullptr,
+                            attrs.type.Reference().GetID(), encoding_data_type,
+                            &attrs.decl, clang_type, resolve_state,
+                            TypePayloadClang(GetOwningClangModule(die)));
 
   dwarf->GetDIEToType()[die.GetDIE()] = type_sp.get();
   return type_sp;
@@ -834,11 +834,11 @@
 
   LinkDeclContextToDIE(TypeSystemClang::GetDeclContextForType(clang_type), die);
 
-  type_sp = dwarf->MakeType(die.GetID(), attrs.name, attrs.byte_size, nullptr,
-                            dwarf->GetUID(attrs.type.Reference()),
-                            Type::eEncodingIsUID, &attrs.decl, clang_type,
-                            Type::ResolveState::Forward,
-                            TypePayloadClang(GetOwningClangModule(die)));
+  type_sp =
+      dwarf->MakeType(die.GetID(), attrs.name, attrs.byte_size, nullptr,
+                      attrs.type.Reference().GetID(), Type::eEncodingIsUID,
+                      &attrs.decl, clang_type, Type::ResolveState::Forward,
+                      TypePayloadClang(GetOwningClangModule(die)));
 
   if (TypeSystemClang::StartTagDeclarationDefinition(clang_type)) {
     if (die.HasChildren()) {
@@ -1336,7 +1336,7 @@
   ConstString empty_name;
   TypeSP type_sp =
       dwarf->MakeType(die.GetID(), empty_name, array_element_bit_stride / 8,
-                      nullptr, dwarf->GetUID(type_die), Type::eEncodingIsUID,
+                      nullptr, type_die.GetID(), Type::eEncodingIsUID,
                       &attrs.decl, clang_type, Type::ResolveState::Full);
   type_sp->SetEncodingType(element_type);
   const clang::Type *type = ClangUtil::GetQualType(clang_type).getTypePtr();
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
@@ -23,8 +23,8 @@
   if (!IsValid())
     return std::nullopt;
 
-  return DIERef(m_cu->GetSymbolFileDWARF().GetDwoNum(), m_cu->GetDebugSection(),
-                m_die->GetOffset());
+  return DIERef(m_cu->GetSymbolFileDWARF().GetFileIndex(),
+                m_cu->GetDebugSection(), m_die->GetOffset());
 }
 
 dw_tag_t DWARFBaseDIE::Tag() const {
@@ -70,8 +70,10 @@
 }
 
 lldb::user_id_t DWARFBaseDIE::GetID() const {
-  if (IsValid())
-    return GetDWARF()->GetUID(*this);
+  const std::optional<DIERef> &ref = this->GetDIERef();
+  if (ref)
+    return ref->get_id();
+
   return LLDB_INVALID_UID;
 }
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
@@ -136,7 +136,7 @@
       });
   uint32_t idx = std::distance(m_units.begin(), pos);
   if (idx == 0)
-    return DW_INVALID_OFFSET;
+    return DW_INVALID_INDEX;
   return idx - 1;
 }
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
@@ -36,7 +36,8 @@
   typedef collection::const_iterator const_iterator;
 
   DWARFDebugInfoEntry()
-      : m_offset(DW_INVALID_OFFSET), m_sibling_idx(0), m_has_children(false) {}
+      : m_offset(DW_INVALID_OFFSET), m_parent_idx(0), m_sibling_idx(0),
+        m_has_children(false) {}
 
   explicit operator bool() const { return m_offset != DW_INVALID_OFFSET; }
   bool operator==(const DWARFDebugInfoEntry &rhs) const;
@@ -165,14 +166,16 @@
   static DWARFDeclContext
   GetDWARFDeclContextStatic(const DWARFDebugInfoEntry *die, DWARFUnit *cu);
 
-  dw_offset_t m_offset; // Offset within the .debug_info/.debug_types
-  uint32_t m_parent_idx = 0;   // How many to subtract from "this" to get the
-                               // parent. If zero this die has no parent
-  uint32_t m_sibling_idx : 31, // How many to add to "this" to get the sibling.
-      // If it is zero, then the DIE doesn't have children, or the
-      // DWARF claimed it had children but the DIE only contained
-      // a single NULL terminating child.
-      m_has_children : 1;
+  // Up to 2TB offset within the .debug_info/.debug_types
+  dw_offset_t m_offset : DW_DIE_OFFSET_MAX_BITSIZE;
+  // How many to subtract from "this" to get the parent. If zero this die has no
+  // parent
+  dw_offset_t m_parent_idx : 64 - DW_DIE_OFFSET_MAX_BITSIZE;
+  // How many to add to "this" to get the sibling.
+  // If it is zero, then the DIE doesn't have children,
+  // or the DWARF claimed it had children but the DIE
+  // only contained a single NULL terminating child.
+  uint32_t m_sibling_idx : 31, m_has_children : 1;
   uint16_t m_abbr_idx = 0;
   /// A copy of the DW_TAG value so we don't have to go through the compile
   /// unit abbrev table
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -64,7 +64,7 @@
         "[{0:x16}]: invalid abbreviation code {1}, "
         "please file a bug and "
         "attach the file at the start of this error message",
-        m_offset, (unsigned)abbr_idx);
+        (uint64_t)m_offset, (unsigned)abbr_idx);
     // WE can't parse anymore if the DWARF is borked...
     *offset_ptr = UINT32_MAX;
     return false;
@@ -195,7 +195,7 @@
               "[{0:x16}]: Unsupported DW_FORM_{1:x}, please file a bug "
               "and "
               "attach the file at the start of this error message",
-              m_offset, (unsigned)form);
+              (uint64_t)m_offset, (unsigned)form);
           *offset_ptr = m_offset;
           return false;
         }
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -341,7 +341,7 @@
   if (const llvm::DWARFUnitIndex::Entry *entry = m_header.GetIndexEntry()) {
     if (const auto *contribution =
             entry->getContribution(llvm::DW_SECT_STR_OFFSETS))
-      baseOffset = contribution->getOffset32();
+      baseOffset = contribution->getOffset();
     else
       return;
   }
@@ -489,7 +489,7 @@
           *GetDWOId());
       return;
     }
-    offset += contribution->getOffset32();
+    offset += contribution->getOffset();
   }
   m_loclists_base = loclists_base;
 
@@ -527,7 +527,7 @@
   if (const llvm::DWARFUnitIndex::Entry *entry = m_header.GetIndexEntry()) {
     if (const auto *contribution = entry->getContribution(
             GetVersion() >= 5 ? llvm::DW_SECT_LOCLISTS : llvm::DW_SECT_EXT_LOC))
-      return DWARFDataExtractor(data, contribution->getOffset32(),
+      return DWARFDataExtractor(data, contribution->getOffset(),
                                 contribution->getLength32());
     return DWARFDataExtractor();
   }
@@ -540,7 +540,7 @@
   if (const llvm::DWARFUnitIndex::Entry *entry = m_header.GetIndexEntry()) {
     if (const auto *contribution =
             entry->getContribution(llvm::DW_SECT_RNGLISTS))
-      return DWARFDataExtractor(data, contribution->getOffset32(),
+      return DWARFDataExtractor(data, contribution->getOffset(),
                                 contribution->getLength32());
     GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
         "Failed to find range list contribution for CU with signature {0:x16}",
@@ -935,7 +935,7 @@
           llvm::inconvertibleErrorCode(),
           "DWARF package index missing abbreviation column");
     }
-    header.m_abbr_offset = abbr_entry->getOffset32();
+    header.m_abbr_offset = abbr_entry->getOffset();
   }
 
   bool length_OK = data.ValidOffset(header.GetNextUnitOffset() - 1);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
@@ -54,7 +54,7 @@
 
   cu = &cu->GetNonSkeletonUnit();
   if (std::optional<uint64_t> die_offset = entry.getDIEUnitOffset())
-    return DIERef(cu->GetSymbolFileDWARF().GetDwoNum(),
+    return DIERef(cu->GetSymbolFileDWARF().GetFileIndex(),
                   DIERef::Section::DebugInfo, cu->GetOffset() + *die_offset);
 
   return std::nullopt;
@@ -126,7 +126,7 @@
 
 void DebugNamesDWARFIndex::GetGlobalVariables(
     DWARFUnit &cu, llvm::function_ref<bool(DWARFDIE die)> callback) {
-  lldbassert(!cu.GetSymbolFileDWARF().GetDwoNum());
+  lldbassert(!cu.GetSymbolFileDWARF().GetFileIndex());
   uint64_t cu_offset = cu.GetOffset();
   bool found_entry_for_cu = false;
   for (const DebugNames::NameIndex &ni: *m_debug_names_up) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -401,7 +401,6 @@
 
 void ManualDWARFIndex::GetGlobalVariables(
     DWARFUnit &unit, llvm::function_ref<bool(DWARFDIE die)> callback) {
-  lldbassert(!unit.GetSymbolFileDWARF().GetDwoNum());
   Index();
   m_set.globals.FindAllEntriesForUnit(unit, DIERefCallback(callback));
 }
@@ -539,7 +538,10 @@
   kDataIDEnd = 255u,
 
 };
-constexpr uint32_t CURRENT_CACHE_VERSION = 1;
+
+// Version 2 changes the encoding of DIERef objects used in the DWARF manual
+// index name tables. See DIERef class for details.
+constexpr uint32_t CURRENT_CACHE_VERSION = 2;
 
 bool ManualDWARFIndex::IndexSet::Decode(const DataExtractor &data,
                                         lldb::offset_t *offset_ptr) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp b/lldb/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
@@ -50,12 +50,11 @@
 
 void NameToDIE::FindAllEntriesForUnit(
     DWARFUnit &s_unit, llvm::function_ref<bool(DIERef ref)> callback) const {
-  lldbassert(!s_unit.GetSymbolFileDWARF().GetDwoNum());
   const DWARFUnit &ns_unit = s_unit.GetNonSkeletonUnit();
   const uint32_t size = m_map.GetSize();
   for (uint32_t i = 0; i < size; ++i) {
     const DIERef &die_ref = m_map.GetValueAtIndexUnchecked(i);
-    if (ns_unit.GetSymbolFileDWARF().GetDwoNum() == die_ref.dwo_num() &&
+    if (ns_unit.GetSymbolFileDWARF().GetFileIndex() == die_ref.file_index() &&
         ns_unit.GetDebugSection() == die_ref.section() &&
         ns_unit.GetOffset() <= die_ref.die_offset() &&
         die_ref.die_offset() < ns_unit.GetNextUnitOffset()) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -55,11 +55,11 @@
 class SymbolFileDWARFDebugMap;
 class SymbolFileDWARFDwo;
 class SymbolFileDWARFDwp;
+class UserID;
 
 #define DIE_IS_BEING_PARSED ((lldb_private::Type *)1)
 
-class SymbolFileDWARF : public lldb_private::SymbolFileCommon,
-                        public lldb_private::UserID {
+class SymbolFileDWARF : public lldb_private::SymbolFileCommon {
   /// LLVM RTTI support.
   static char ID;
 
@@ -265,22 +265,10 @@
 
   DWARFDIE GetDIE(lldb::user_id_t uid);
 
-  lldb::user_id_t GetUID(const DWARFBaseDIE &die) {
-    return GetUID(die.GetDIERef());
-  }
-
-  lldb::user_id_t GetUID(const std::optional<DIERef> &ref) {
-    return ref ? GetUID(*ref) : LLDB_INVALID_UID;
-  }
-
-  lldb::user_id_t GetUID(DIERef ref);
-
   std::shared_ptr<SymbolFileDWARFDwo>
   GetDwoSymbolFileForCompileUnit(DWARFUnit &dwarf_cu,
                                  const DWARFDebugInfoEntry &cu_die);
 
-  virtual std::optional<uint32_t> GetDwoNum() { return std::nullopt; }
-
   /// If this is a DWARF object with a single CU, return its DW_AT_dwo_id.
   std::optional<uint64_t> GetDWOId();
 
@@ -289,7 +277,7 @@
                    const DWARFDIE &die);
 
   std::vector<std::unique_ptr<lldb_private::CallEdge>>
-  ParseCallEdgesInFunction(UserID func_id) override;
+  ParseCallEdgesInFunction(lldb_private::UserID func_id) override;
 
   void Dump(lldb_private::Stream &s) override;
 
@@ -347,6 +335,11 @@
 
   lldb_private::ConstString ConstructFunctionDemangledName(const DWARFDIE &die);
 
+  std::optional<uint64_t> GetFileIndex() const { return m_file_index; }
+  void SetFileIndex(std::optional<uint64_t> file_index) {
+    m_file_index = file_index;
+  }
+
 protected:
   typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb_private::Type *>
       DIEToTypePtr;
@@ -521,12 +514,6 @@
   void BuildCuTranslationTable();
   std::optional<uint32_t> GetDWARFUnitIndex(uint32_t cu_idx);
 
-  struct DecodedUID {
-    SymbolFileDWARF &dwarf;
-    DIERef ref;
-  };
-  std::optional<DecodedUID> DecodeUID(lldb::user_id_t uid);
-
   void FindDwpSymbolFile();
 
   const lldb_private::FileSpecList &GetTypeUnitSupportFiles(DWARFTypeUnit &tu);
@@ -580,6 +567,11 @@
   lldb::addr_t m_first_code_address = LLDB_INVALID_ADDRESS;
   lldb_private::StatsDuration m_parse_time;
   std::atomic_flag m_dwo_warning_issued = ATOMIC_FLAG_INIT;
+  /// If this DWARF file a .DWO file or a DWARF .o file on mac when
+  /// no dSYM file is being used, this file index will be set to a
+  /// valid value that can be used in DIERef objects which will contain
+  /// an index that identifies the .DWO or .o file.
+  std::optional<uint64_t> m_file_index = std::nullopt;
 };
 
 #endif // LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARF_H
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -408,11 +408,8 @@
 
 SymbolFileDWARF::SymbolFileDWARF(ObjectFileSP objfile_sp,
                                  SectionList *dwo_section_list)
-    : SymbolFileCommon(std::move(objfile_sp)),
-      UserID(0x7fffffff00000000), // Used by SymbolFileDWARFDebugMap to
-                                  // when this class parses .o files to
-                                  // contain the .o file index/ID
-      m_debug_map_module_wp(), m_debug_map_symfile(nullptr),
+    : SymbolFileCommon(std::move(objfile_sp)), m_debug_map_module_wp(),
+      m_debug_map_symfile(nullptr),
       m_context(m_objfile_sp->GetModule()->GetSectionList(), dwo_section_list),
       m_fetched_external_modules(false),
       m_supports_DW_AT_APPLE_objc_complete_type(eLazyBoolCalculate) {}
@@ -587,6 +584,14 @@
       }
     }
 
+    constexpr uint64_t MaxDebugInfoSize = (1ull) << DW_DIE_OFFSET_MAX_BITSIZE;
+    if (debug_info_file_size >= MaxDebugInfoSize) {
+      m_objfile_sp->GetModule()->ReportWarning(
+          "SymbolFileDWARF can't load this DWARF. It's larger then {0:x+16}",
+          MaxDebugInfoSize);
+      return 0;
+    }
+
     if (debug_abbrev_file_size > 0 && debug_info_file_size > 0)
       abilities |= CompileUnits | Functions | Blocks | GlobalVariables |
                    LocalVariables | VariableTypes;
@@ -1396,62 +1401,8 @@
         decl_ctx);
 }
 
-user_id_t SymbolFileDWARF::GetUID(DIERef ref) {
-  if (GetDebugMapSymfile())
-    return GetID() | ref.die_offset();
-
-  lldbassert(GetDwoNum().value_or(0) <= 0x3fffffff);
-  return user_id_t(GetDwoNum().value_or(0)) << 32 | ref.die_offset() |
-         lldb::user_id_t(GetDwoNum().has_value()) << 62 |
-         lldb::user_id_t(ref.section() == DIERef::Section::DebugTypes) << 63;
-}
-
-std::optional<SymbolFileDWARF::DecodedUID>
-SymbolFileDWARF::DecodeUID(lldb::user_id_t uid) {
-  // This method can be called without going through the symbol vendor so we
-  // need to lock the module.
-  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
-  // Anytime we get a "lldb::user_id_t" from an lldb_private::SymbolFile API we
-  // must make sure we use the correct DWARF file when resolving things. On
-  // MacOSX, when using SymbolFileDWARFDebugMap, we will use multiple
-  // SymbolFileDWARF classes, one for each .o file. We can often end up with
-  // references to other DWARF objects and we must be ready to receive a
-  // "lldb::user_id_t" that specifies a DIE from another SymbolFileDWARF
-  // instance.
-  if (SymbolFileDWARFDebugMap *debug_map = GetDebugMapSymfile()) {
-    SymbolFileDWARF *dwarf = debug_map->GetSymbolFileByOSOIndex(
-        debug_map->GetOSOIndexFromUserID(uid));
-    return DecodedUID{
-        *dwarf, {std::nullopt, DIERef::Section::DebugInfo, dw_offset_t(uid)}};
-  }
-  dw_offset_t die_offset = uid;
-  if (die_offset == DW_INVALID_OFFSET)
-    return std::nullopt;
-
-  DIERef::Section section =
-      uid >> 63 ? DIERef::Section::DebugTypes : DIERef::Section::DebugInfo;
-
-  std::optional<uint32_t> dwo_num;
-  bool dwo_valid = uid >> 62 & 1;
-  if (dwo_valid)
-    dwo_num = uid >> 32 & 0x3fffffff;
-
-  return DecodedUID{*this, {dwo_num, section, die_offset}};
-}
-
 DWARFDIE
-SymbolFileDWARF::GetDIE(lldb::user_id_t uid) {
-  // This method can be called without going through the symbol vendor so we
-  // need to lock the module.
-  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
-
-  std::optional<DecodedUID> decoded = DecodeUID(uid);
-
-  if (decoded)
-    return decoded->dwarf.GetDIE(decoded->ref);
-
-  return DWARFDIE();
-}
+SymbolFileDWARF::GetDIE(lldb::user_id_t uid) { return GetDIE(DIERef(uid)); }
 
 CompilerDecl SymbolFileDWARF::GetDeclForUID(lldb::user_id_t type_uid) {
   // This method can be called without going through the symbol vendor so we
@@ -1693,15 +1644,41 @@
 
 DWARFDIE
 SymbolFileDWARF::GetDIE(const DIERef &die_ref) {
-  if (die_ref.dwo_num()) {
-    SymbolFileDWARF *dwarf = *die_ref.dwo_num() == 0x3fffffff
-                                 ? m_dwp_symfile.get()
-                                 : this->DebugInfo()
-                                       .GetUnitAtIndex(*die_ref.dwo_num())
-                                       ->GetDwoSymbolFile();
-    return dwarf->DebugInfo().GetDIE(die_ref);
+  // This method can be called without going through the symbol vendor so we
+  // need to lock the module.
+  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
+
+  SymbolFileDWARF *symbol_file = nullptr;
+
+  // Anytime we get a "lldb::user_id_t" from an lldb_private::SymbolFile API we
+  // must make sure we use the correct DWARF file when resolving things. On
+  // MacOSX, when using SymbolFileDWARFDebugMap, we will use multiple
+  // SymbolFileDWARF classes, one for each .o file. We can often end up with
+  // references to other DWARF objects and we must be ready to receive a
+  // "lldb::user_id_t" that specifies a DIE from another SymbolFileDWARF
+  // instance.
+  std::optional<uint32_t> file_index = die_ref.file_index();
+  if (file_index) {
+    if (SymbolFileDWARFDebugMap *debug_map = GetDebugMapSymfile()) {
+      symbol_file = debug_map->GetSymbolFileByOSOIndex(*file_index); // OSO case
+      if (symbol_file)
+        return symbol_file->DebugInfo().GetDIE(die_ref);
+      return DWARFDIE();
+    }
+
+    if (*file_index == DIERef::k_file_index_mask)
+      symbol_file = m_dwp_symfile.get(); // DWP case
+    else
+      symbol_file = this->DebugInfo()
+                        .GetUnitAtIndex(*die_ref.file_index())
+                        ->GetDwoSymbolFile(); // DWO case
+  } else if (die_ref.die_offset() == DW_INVALID_OFFSET) {
+    return DWARFDIE();
   }
 
+  if (symbol_file)
+    return symbol_file->GetDIE(die_ref);
+
   return DebugInfo().GetDIE(die_ref);
 }
 
@@ -3190,7 +3167,7 @@
     return 0;
 
   size_t functions_added = 0;
-  const dw_offset_t function_die_offset = func.GetID();
+  const dw_offset_t function_die_offset = DIERef(func.GetID()).die_offset();
   DWARFDIE function_die =
       dwarf_cu->GetNonSkeletonUnit().GetDIE(function_die_offset);
   if (function_die) {
@@ -3612,7 +3589,7 @@
   }
 
   auto type_sp = std::make_shared<SymbolFileType>(
-      *this, GetUID(type_die_form.Reference()));
+      *this, type_die_form.Reference().GetID());
 
   if (use_type_size_for_value && type_sp->GetType()) {
     DWARFExpression *location = location_list.GetMutableExpressionAtAddress();
@@ -4108,7 +4085,7 @@
 }
 
 std::vector<std::unique_ptr<lldb_private::CallEdge>>
-SymbolFileDWARF::ParseCallEdgesInFunction(UserID func_id) {
+SymbolFileDWARF::ParseCallEdgesInFunction(lldb_private::UserID func_id) {
   // ParseCallEdgesInFunction must be called at the behest of an exclusively
   // locked lldb::Function instance. Storage for parsed call edges is owned by
   // the lldb::Function instance: locking at the SymbolFile level would be too
@@ -4166,8 +4143,8 @@
           dwp_file_data_offset);
       if (!dwp_obj_file)
         return;
-      m_dwp_symfile =
-          std::make_shared<SymbolFileDWARFDwo>(*this, dwp_obj_file, 0x3fffffff);
+      m_dwp_symfile = std::make_shared<SymbolFileDWARFDwo>(
+          *this, dwp_obj_file, DIERef::k_file_index_mask);
     }
   });
   return m_dwp_symfile;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -9,6 +9,7 @@
 #ifndef LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARFDEBUGMAP_H
 #define LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARFDEBUGMAP_H
 
+#include "DIERef.h"
 #include "lldb/Symbol/SymbolFile.h"
 #include "lldb/Utility/RangeMap.h"
 #include "llvm/Support/Chrono.h"
@@ -209,7 +210,9 @@
   lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
 
   static uint32_t GetOSOIndexFromUserID(lldb::user_id_t uid) {
-    return (uint32_t)((uid >> 32ull) - 1ull);
+    std::optional<uint32_t> OsoNum = DIERef(uid).file_index();
+    lldbassert(OsoNum && "Invalid OSO Index");
+    return *OsoNum;
   }
 
   static SymbolFileDWARF *GetSymbolFileAsSymbolFileDWARF(SymbolFile *sym_file);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -211,7 +211,7 @@
             // Set the ID of the symbol file DWARF to the index of the OSO
             // shifted left by 32 bits to provide a unique prefix for any
             // UserID's that get created in the symbol file.
-            oso_symfile->SetID(((uint64_t)m_cu_idx + 1ull) << 32ull);
+            oso_symfile->SetFileIndex((uint64_t)m_cu_idx);
           }
           return symfile;
         }
@@ -1121,7 +1121,8 @@
 }
 
 std::vector<std::unique_ptr<lldb_private::CallEdge>>
-SymbolFileDWARFDebugMap::ParseCallEdgesInFunction(UserID func_id) {
+SymbolFileDWARFDebugMap::ParseCallEdgesInFunction(
+    lldb_private::UserID func_id) {
   uint32_t oso_idx = GetOSOIndexFromUserID(func_id.GetID());
   SymbolFileDWARF *oso_dwarf = GetSymbolFileByOSOIndex(oso_idx);
   if (oso_dwarf)
@@ -1468,7 +1469,8 @@
       for (size_t idx = 0; idx < file_range_map.GetSize(); idx++) {
         const FileRangeMap::Entry *entry = file_range_map.GetEntryAtIndex(idx);
         if (entry) {
-          debug_aranges->AppendRange(dwarf2Data->GetID(), entry->GetRangeBase(),
+          debug_aranges->AppendRange(*dwarf2Data->GetFileIndex(),
+                                     entry->GetRangeBase(),
                                      entry->GetRangeEnd());
           num_line_entries_added++;
         }
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
@@ -41,8 +41,6 @@
   DWARFDIE
   GetDIE(const DIERef &die_ref) override;
 
-  std::optional<uint32_t> GetDwoNum() override { return GetID() >> 32; }
-
   lldb::offset_t
   GetVendorDWARFOpcodeSize(const lldb_private::DataExtractor &data,
                            const lldb::offset_t data_offset,
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
@@ -29,7 +29,7 @@
     : SymbolFileDWARF(objfile, objfile->GetSectionList(
                                    /*update_module_section_list*/ false)),
       m_base_symbol_file(base_symbol_file) {
-  SetID(user_id_t(id) << 32);
+  SetFileIndex(id);
 
   // Parsing of the dwarf unit index is not thread-safe, so we need to prime it
   // to enable subsequent concurrent lookups.
@@ -42,7 +42,7 @@
       if (auto *unit_contrib = entry->getContribution())
         return llvm::dyn_cast_or_null<DWARFCompileUnit>(
             DebugInfo().GetUnitAtOffset(DIERef::Section::DebugInfo,
-                                        unit_contrib->getOffset32()));
+                                        unit_contrib->getOffset()));
     }
     return nullptr;
   }
@@ -137,7 +137,7 @@
 
 DWARFDIE
 SymbolFileDWARFDwo::GetDIE(const DIERef &die_ref) {
-  if (die_ref.dwo_num() == GetDwoNum())
+  if (die_ref.file_index() == GetFileIndex())
     return DebugInfo().GetDIE(die_ref);
   return GetBaseSymbolFile().GetDIE(die_ref);
 }
diff --git a/lldb/test/Shell/SymbolFile/DWARF/DW_AT_range-DW_FORM_sec_offset.s b/lldb/test/Shell/SymbolFile/DWARF/DW_AT_range-DW_FORM_sec_offset.s
--- a/lldb/test/Shell/SymbolFile/DWARF/DW_AT_range-DW_FORM_sec_offset.s
+++ b/lldb/test/Shell/SymbolFile/DWARF/DW_AT_range-DW_FORM_sec_offset.s
@@ -8,7 +8,7 @@
 # RUN:   -o exit | FileCheck %s
 
 # Failure was the block range 1..2 was not printed plus:
-# error: DW_AT_range-DW_FORM_sec_offset.s.tmp {0x0000003f}: DIE has DW_AT_ranges(0xc) attribute, but range extraction failed (missing or invalid range list table), please file a bug and attach the file at the start of this error message
+# error: DW_AT_range-DW_FORM_sec_offset.s.tmp {0x000000000000003f}: DIE has DW_AT_ranges(0xc) attribute, but range extraction failed (missing or invalid range list table), please file a bug and attach the file at the start of this error message
 
 # CHECK-LABEL: image lookup -v -s lookup_rnglists
 # CHECK:  Function: id = {0x00000029}, name = "rnglists", range = [0x0000000000000000-0x0000000000000003)
diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp
--- a/lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -713,7 +713,7 @@
   //       Entries:
   //         - AbbrCode:        0x1
   //           Values:
-  //             - Value:           0x01020304
+  //             - Value:           0x0120304
   //         - AbbrCode:        0x0
   const char *dwo_yamldata = R"(
 --- !ELF
@@ -750,7 +750,7 @@
   auto dwo_module_sp = std::make_shared<Module>(dwo_file->moduleSpec());
   SymbolFileDWARFDwo dwo_symfile(
       skeleton_symfile, dwo_module_sp->GetObjectFile()->shared_from_this(),
-      0x01020304);
+      0x0120304);
   auto *dwo_dwarf_unit = dwo_symfile.DebugInfo().GetUnitAtIndex(0);
 
   testExpressionVendorExtensions(dwo_module_sp, *dwo_dwarf_unit);
diff --git a/lldb/unittests/SymbolFile/DWARF/DWARFIndexCachingTest.cpp b/lldb/unittests/SymbolFile/DWARF/DWARFIndexCachingTest.cpp
--- a/lldb/unittests/SymbolFile/DWARF/DWARFIndexCachingTest.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/DWARFIndexCachingTest.cpp
@@ -45,6 +45,26 @@
   EncodeDecode(DIERef(200, DIERef::Section::DebugTypes, 0x11223344));
 }
 
+TEST(DWARFIndexCachingTest, DIERefEncodeDecodeMax) {
+  // Tests DIERef::Encode(...) and DIERef::Decode(...)
+  EncodeDecode(DIERef(std::nullopt, DIERef::Section::DebugInfo,
+                      DIERef::k_die_offset_mask - 1));
+  EncodeDecode(DIERef(std::nullopt, DIERef::Section::DebugTypes,
+                      DIERef::k_die_offset_mask - 1));
+  EncodeDecode(
+      DIERef(100, DIERef::Section::DebugInfo, DIERef::k_die_offset_mask - 1));
+  EncodeDecode(
+      DIERef(200, DIERef::Section::DebugTypes, DIERef::k_die_offset_mask - 1));
+  EncodeDecode(DIERef(DIERef::k_file_index_mask, DIERef::Section::DebugInfo,
+                      DIERef::k_file_index_mask));
+  EncodeDecode(DIERef(DIERef::k_file_index_mask, DIERef::Section::DebugTypes,
+                      DIERef::k_file_index_mask));
+  EncodeDecode(DIERef(DIERef::k_file_index_mask, DIERef::Section::DebugInfo,
+                      0x11223344));
+  EncodeDecode(DIERef(DIERef::k_file_index_mask, DIERef::Section::DebugTypes,
+                      0x11223344));
+}
+
 static void EncodeDecode(const NameToDIE &object, ByteOrder byte_order) {
   const uint8_t addr_size = 8;
   DataEncoder encoder(byte_order, addr_size);