Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -32,6 +32,14 @@
 
 enum class BuildIdKind { None, Fnv1, Md5, Sha1, Hexstring };
 
+// This struct contains symbols version definition that
+// can be found in version script if it is used for link.
+struct Version {
+  Version(llvm::StringRef Name) { this->Name = Name; }
+  llvm::StringRef Name;
+  std::vector<llvm::StringRef> Globals;
+};
+
 // This struct contains the global configuration for the linker.
 // Most fields are direct mapping from the command line options
 // and such fields have the same name as the corresponding options.
@@ -50,6 +58,7 @@
   llvm::StringRef SoName;
   llvm::StringRef Sysroot;
   std::string RPath;
+  std::vector<Version> SymbolVersions;
   std::vector<llvm::StringRef> DynamicList;
   std::vector<llvm::StringRef> SearchPaths;
   std::vector<llvm::StringRef> Undefined;
Index: ELF/OutputSections.h
===================================================================
--- ELF/OutputSections.h
+++ ELF/OutputSections.h
@@ -24,6 +24,7 @@
 
 class SymbolBody;
 struct SectionPiece;
+struct Version;
 template <class ELFT> class SymbolTable;
 template <class ELFT> class SymbolTableSection;
 template <class ELFT> class StringTableSection;
@@ -230,6 +231,34 @@
 // For more information about .gnu.version and .gnu.version_r see:
 // https://www.akkadia.org/drepper/symbol-versioning
 
+// The .gnu.version_d section which has a section type of SHT_GNU_verdef shall
+// contain symbol version definitions. The number of entries in this section
+// shall be contained in the DT_VERDEFNUM entry of the .dynamic section.
+// The section shall contain an array of Elf_Verdef structures, optionally
+// followed by an array of Elf_Verdaux structures.
+template <class ELFT>
+class VersionDefinitionSection final : public OutputSectionBase<ELFT> {
+  typedef typename ELFT::Verdef Elf_Verdef;
+  typedef typename ELFT::Verdaux Elf_Verdaux;
+
+  struct VerDefEntry {
+    uint32_t Flags; // Version definition flags.
+    uint32_t Hash;  // Name hash.
+    size_t NameOff; // Offset in string table.
+    size_t Ndx;     // Version definition index.
+  };
+
+  llvm::DenseMap<Version *, VerDefEntry> VerDefs;
+
+public:
+  VersionDefinitionSection();
+  void finalize() override;
+  void writeTo(uint8_t *Buf) override;
+  void createDefs();
+
+  unsigned getVerDefId(Version *Ver);
+};
+
 // The .gnu.version section specifies the required version of each symbol in the
 // dynamic symbol table. It contains one Elf_Versym for each dynamic symbol
 // table entry. An Elf_Versym is just a 16-bit integer that refers to a version
@@ -242,6 +271,7 @@
   VersionTableSection();
   void finalize() override;
   void writeTo(uint8_t *Buf) override;
+  bool isRequired();
 };
 
 // The .gnu.version_r section defines the version identifiers used by
@@ -258,9 +288,8 @@
   // string table offsets of their sonames.
   std::vector<std::pair<SharedFile<ELFT> *, size_t>> Needed;
 
-  // The next available version identifier. Identifiers start at 2 because 0 and
-  // 1 are reserved.
-  unsigned NextIndex = 2;
+  // The next available version identifier.
+  unsigned NextIndex;
 
 public:
   VersionNeedSection();
@@ -612,6 +641,7 @@
   static StringTableSection<ELFT> *StrTab;
   static SymbolTableSection<ELFT> *DynSymTab;
   static SymbolTableSection<ELFT> *SymTab;
+  static VersionDefinitionSection<ELFT> *VerDef;
   static VersionTableSection<ELFT> *VerSym;
   static VersionNeedSection<ELFT> *VerNeed;
   static Elf_Phdr *TlsPhdr;
@@ -640,6 +670,7 @@
 template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::StrTab;
 template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::DynSymTab;
 template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::SymTab;
+template <class ELFT> VersionDefinitionSection<ELFT> *Out<ELFT>::VerDef;
 template <class ELFT> VersionTableSection<ELFT> *Out<ELFT>::VerSym;
 template <class ELFT> VersionNeedSection<ELFT> *Out<ELFT>::VerNeed;
 template <class ELFT> typename ELFT::Phdr *Out<ELFT>::TlsPhdr;
Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -563,6 +563,16 @@
     V.push_back({Sym.Body, Sym.STName});
 }
 
+static unsigned getVerDefNum() {
+  // At least one version dependency must exist. Additional version dependencies
+  // can be present, the number being indicated by the vn_cnt value of
+  // Elf_Verdef. We do not support version hierarchies currently, so each
+  // Elf_Verdef associated exactly with single Elf_Verdaux for us.
+  // The base version definition is always present when version definitions, or
+  // symbol auto-reduction, have been applied to the file.
+  return Config->SymbolVersions.size() + 1;
+}
+
 template <class ELFT>
 DynamicSection<ELFT>::DynamicSection()
     : OutputSectionBase<ELFT>(".dynamic", SHT_DYNAMIC, SHF_ALLOC | SHF_WRITE) {
@@ -665,8 +675,15 @@
   if (!Config->Entry.empty())
     Add({DT_DEBUG, (uint64_t)0});
 
-  if (size_t NeedNum = Out<ELFT>::VerNeed->getNeedNum()) {
+  if (Out<ELFT>::VerSym->isRequired())
     Add({DT_VERSYM, Out<ELFT>::VerSym});
+
+  if (!Config->SymbolVersions.empty()) {
+    Add({DT_VERDEF, Out<ELFT>::VerDef});
+    Add({DT_VERDEFNUM, getVerDefNum()});
+  }
+
+  if (size_t NeedNum = Out<ELFT>::VerNeed->getNeedNum()) {
     Add({DT_VERNEED, Out<ELFT>::VerNeed});
     Add({DT_VERNEEDNUM, NeedNum});
   }
@@ -1407,6 +1424,65 @@
 }
 
 template <class ELFT>
+VersionDefinitionSection<ELFT>::VersionDefinitionSection()
+    : OutputSectionBase<ELFT>(".gnu.version_d", SHT_GNU_verdef, SHF_ALLOC) {}
+
+template <class ELFT> void VersionDefinitionSection<ELFT>::createDefs() {
+  size_t I = 1;
+  VerDefs[nullptr] = {VER_FLG_BASE, hashSysv(Config->OutputFile),
+                      Out<ELFT>::DynStrTab->addString(Config->OutputFile), I++};
+  for (Version &V : Config->SymbolVersions) {
+    VerDefs[&V] = {0, hashSysv(V.Name), Out<ELFT>::DynStrTab->addString(V.Name),
+                   I++};
+  } // Without this and opening bracket it does not compile under VS2015.
+}
+
+template <class ELFT> void VersionDefinitionSection<ELFT>::finalize() {
+  this->Header.sh_size =
+      (sizeof(Elf_Verdef) + sizeof(Elf_Verdaux)) * getVerDefNum();
+  this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
+
+  // sh_info should be set to amount of definitions. This fact is missed in
+  // documentation, but confirmed by binutils community:
+  // https://sourceware.org/ml/binutils/2014-11/msg00355.html
+  this->Header.sh_info = getVerDefNum();
+}
+
+template <class ELFT>
+void VersionDefinitionSection<ELFT>::writeTo(uint8_t *Buf) {
+  Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
+  Elf_Verdaux *Verdaux =
+      reinterpret_cast<Elf_Verdaux *>(Verdef + getVerDefNum());
+
+  for (std::pair<Version *, VerDefEntry> &VD : VerDefs) {
+    VerDefEntry& Def = VD.second;
+
+    Verdef->vd_version = 1;
+    Verdef->vd_flags = Def.Flags;
+    Verdef->vd_ndx = Def.Ndx;
+    Verdef->vd_cnt = 1;
+    Verdef->vd_hash = Def.Hash;
+
+    Verdef->vd_aux =
+        reinterpret_cast<char *>(Verdaux) - reinterpret_cast<char *>(Verdef);
+    Verdef->vd_next = sizeof(Elf_Verdef);
+    ++Verdef;
+
+    // Now write the single Elf_Verdaux entry.
+    Verdaux->vda_name = Def.NameOff;
+    Verdaux->vda_next = 0;
+    ++Verdaux;
+  }
+
+  Verdef[-1].vd_next = 0;
+}
+
+template <class ELFT>
+unsigned VersionDefinitionSection<ELFT>::getVerDefId(Version *Ver) {
+  return VerDefs.find(Ver)->second.Ndx;
+}
+
+template <class ELFT>
 VersionTableSection<ELFT>::VersionTableSection()
     : OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {
   this->Header.sh_addralign = sizeof(uint16_t);
@@ -1422,21 +1498,41 @@
 }
 
 template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
-  auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
+  auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf);
   for (const std::pair<SymbolBody *, size_t> &P :
        Out<ELFT>::DynSymTab->getSymbols()) {
-    if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(P.first))
+    ++OutVersym;
+
+    SymbolBody *Body = P.first;
+    if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(Body)) {
       OutVersym->vs_index = SS->VersionId;
-    else
+      continue;
+    }
+    if (!Body->VerDef) {
       OutVersym->vs_index = VER_NDX_GLOBAL;
-    ++OutVersym;
+      continue;
+    }
+
+    OutVersym->vs_index = Out<ELFT>::VerDef->getVerDefId(Body->VerDef);
   }
 }
 
+template <class ELFT> bool VersionTableSection<ELFT>::isRequired() {
+  return !Config->SymbolVersions.empty() ||
+         Out<ELFT>::VerNeed->getNeedNum() != 0;
+}
+
 template <class ELFT>
 VersionNeedSection<ELFT>::VersionNeedSection()
     : OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {
   this->Header.sh_addralign = sizeof(uint32_t);
+
+  // Identifiers in verneed section start at 2 because 0 and 1 are reserved
+  // for VER_NDX_LOCAL and VER_NDX_GLOBAL.
+  // First identifiers are reserved by verdef section if it is exist.
+  NextIndex = 2;
+  if (!Config->SymbolVersions.empty())
+    NextIndex = std::max(getVerDefNum() + 1, NextIndex);
 }
 
 template <class ELFT>
@@ -1716,6 +1812,11 @@
 template class VersionNeedSection<ELF64LE>;
 template class VersionNeedSection<ELF64BE>;
 
+template class VersionDefinitionSection<ELF32LE>;
+template class VersionDefinitionSection<ELF32BE>;
+template class VersionDefinitionSection<ELF64LE>;
+template class VersionDefinitionSection<ELF64BE>;
+
 template class BuildIdSection<ELF32LE>;
 template class BuildIdSection<ELF32BE>;
 template class BuildIdSection<ELF64LE>;
Index: ELF/SymbolListFile.h
===================================================================
--- ELF/SymbolListFile.h
+++ ELF/SymbolListFile.h
@@ -11,6 +11,7 @@
 #define LLD_ELF_SYMBOL_LIST_FILE_H
 
 #include "lld/Core/LLVM.h"
+#include "llvm/ADT/MapVector.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 namespace lld {
Index: ELF/SymbolListFile.cpp
===================================================================
--- ELF/SymbolListFile.cpp
+++ ELF/SymbolListFile.cpp
@@ -75,9 +75,13 @@
   VersionScriptParser(StringRef S) : ScriptParserBase(S) {}
 
   void run();
+
+private:
+  void parseUnversionedScript();
+  void parseVersionedScript();
 };
 
-void VersionScriptParser::run() {
+void VersionScriptParser::parseUnversionedScript() {
   expect("{");
   if (peek() == "global:") {
     next();
@@ -97,6 +101,43 @@
     setError("expected EOF");
 }
 
+void VersionScriptParser::parseVersionedScript() {
+  while (!atEOF() && !Error) {
+    Config->SymbolVersions.push_back(Version(next()));
+    Version &V = Config->SymbolVersions.back();
+
+    expect("{");
+    if (peek() == "global:") {
+      next();
+      while (!Error) {
+        V.Globals.push_back(next());
+        expect(";");
+        if (peek() == "local:" || peek() == "}")
+          break;
+      }
+    }
+
+    if (peek() == "local:") {
+      expect("local:");
+      expect("*");
+      expect(";");
+    }
+
+    expect("}");
+    // Skip parent if exist.
+    if (peek() != ";")
+      next();
+    expect(";");
+  }
+}
+
+void VersionScriptParser::run() {
+  if (peek() == "{")
+    parseUnversionedScript();
+  else
+    parseVersionedScript();
+}
+
 void elf::parseVersionScript(MemoryBufferRef MB) {
   VersionScriptParser(MB.getBuffer()).run();
 }
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -510,9 +510,21 @@
 // symbols with the VersionScriptGlobal flag, which acts as a filter on the
 // dynamic symbol table.
 template <class ELFT> void SymbolTable<ELFT>::scanVersionScript() {
-  for (StringRef S : Config->VersionScriptGlobals)
-    if (SymbolBody *B = find(S))
-      B->symbol()->VersionScriptGlobal = true;
+  // If version script does not contain versions declarations,
+  // we just should mark global symbols.
+  if (!Config->VersionScriptGlobals.empty()) {
+    for (StringRef S : Config->VersionScriptGlobals)
+      if (SymbolBody *B = find(S))
+        B->symbol()->VersionScriptGlobal = true;
+    return;
+  }
+
+  // If we have symbols version declarations, we should
+  // assign version references for each symbol.
+  for (Version &V : Config->SymbolVersions)
+    for (StringRef Name : V.Globals)
+      if (SymbolBody *B = find(Name))
+        B->VerDef = &V;
 }
 
 template class elf::SymbolTable<ELF32LE>;
Index: ELF/Symbols.h
===================================================================
--- ELF/Symbols.h
+++ ELF/Symbols.h
@@ -29,6 +29,7 @@
 class BitcodeFile;
 class InputFile;
 class SymbolBody;
+struct Version;
 template <class ELFT> class ObjectFile;
 template <class ELFT> class OutputSection;
 template <class ELFT> class OutputSectionBase;
@@ -137,6 +138,9 @@
   // symbol's type in order to check for TLS mismatches.
   enum { UnknownType = 255 };
 
+  // This is reference to version definition for symbol.
+  Version* VerDef = nullptr;
+
   bool isSection() const { return Type == llvm::ELF::STT_SECTION; }
   bool isTls() const { return Type == llvm::ELF::STT_TLS; }
   bool isFunc() const { return Type == llvm::ELF::STT_FUNC; }
Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -263,8 +263,8 @@
 bool Symbol::includeInDynsym() const {
   if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
     return false;
-  return (ExportDynamic && VersionScriptGlobal) || body()->isShared() ||
-         (body()->isUndefined() && Config->Shared);
+  return (ExportDynamic && (VersionScriptGlobal || body()->VerDef)) ||
+         body()->isShared() || (body()->isUndefined() && Config->Shared);
 }
 
 template InputFile *SymbolBody::template getSourceFile<ELF32LE>();
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -118,6 +118,7 @@
   StringTableSection<ELFT> DynStrTab(".dynstr", true);
   StringTableSection<ELFT> ShStrTab(".shstrtab", false);
   SymbolTableSection<ELFT> DynSymTab(DynStrTab);
+  VersionDefinitionSection<ELFT> VerDef;
   VersionTableSection<ELFT> VerSym;
   VersionNeedSection<ELFT> VerNeed;
 
@@ -189,6 +190,7 @@
   Out<ELFT>::ShStrTab = &ShStrTab;
   Out<ELFT>::StrTab = StrTab.get();
   Out<ELFT>::SymTab = SymTabSec.get();
+  Out<ELFT>::VerDef = &VerDef;
   Out<ELFT>::VerSym = &VerSym;
   Out<ELFT>::VerNeed = &VerNeed;
   Out<ELFT>::MipsRldMap = MipsRldMap.get();
@@ -807,6 +809,9 @@
     });
   }
 
+  if (!Config->SymbolVersions.empty())
+    Out<ELFT>::VerDef->createDefs();
+
   // Now that we have defined all possible symbols including linker-
   // synthesized ones. Visit all symbols to give the finishing touches.
   std::vector<DefinedCommon *> CommonSymbols;
@@ -904,10 +909,14 @@
   Add(Out<ELFT>::StrTab);
   if (isOutputDynamic()) {
     Add(Out<ELFT>::DynSymTab);
-    if (Out<ELFT>::VerNeed->getNeedNum() != 0) {
+
+    if (Out<ELFT>::VerSym->isRequired())
       Add(Out<ELFT>::VerSym);
+    if (!Config->SymbolVersions.empty())
+      Add(Out<ELFT>::VerDef);
+    if (Out<ELFT>::VerNeed->getNeedNum() != 0)
       Add(Out<ELFT>::VerNeed);
-    }
+
     Add(Out<ELFT>::GnuHashTab);
     Add(Out<ELFT>::HashTab);
     Add(Out<ELFT>::Dynamic);
Index: test/ELF/Inputs/verdef.s
===================================================================
--- test/ELF/Inputs/verdef.s
+++ test/ELF/Inputs/verdef.s
@@ -0,0 +1,6 @@
+.text
+.globl _start
+_start:
+ callq a
+ callq b
+ callq c
Index: test/ELF/verdef.s
===================================================================
--- test/ELF/verdef.s
+++ test/ELF/verdef.s
@@ -0,0 +1,131 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "LIBSAMPLE_1.0{  \
+# RUN:          global: a;   \
+# RUN:          local: *; }; \
+# RUN:       LIBSAMPLE_2.0{  \
+# RUN:          global: b;   \
+# RUN:          local: *; }; \
+# RUN:       LIBSAMPLE_3.0{  \
+# RUN:          global: c;   \
+# RUN:          local: *; };" > %t.script
+# RUN: ld.lld --version-script %t.script -shared %t.o -o %t.so
+# RUN: llvm-readobj -V %t.so | FileCheck --check-prefix=DSO %s
+
+# DSO:        Version symbols {
+# DSO-NEXT:   Section Name: .gnu.version
+# DSO-NEXT:   Address: 0x228
+# DSO-NEXT:   Offset: 0x228
+# DSO-NEXT:   Link: 1
+# DSO-NEXT:   Symbols [
+# DSO-NEXT:     Symbol {
+# DSO-NEXT:       Version: 0
+# DSO-NEXT:       Name: @
+# DSO-NEXT:     }
+# DSO-NEXT:     Symbol {
+# DSO-NEXT:       Version: 2
+# DSO-NEXT:       Name: a@@LIBSAMPLE_1.0
+# DSO-NEXT:     }
+# DSO-NEXT:     Symbol {
+# DSO-NEXT:       Version: 3
+# DSO-NEXT:       Name: b@@LIBSAMPLE_2.0
+# DSO-NEXT:     }
+# DSO-NEXT:     Symbol {
+# DSO-NEXT:       Version: 4
+# DSO-NEXT:       Name: c@@LIBSAMPLE_3.0
+# DSO-NEXT:     }
+# DSO-NEXT:   ]
+# DSO-NEXT: }
+# DSO-NEXT: Version definition {
+# DSO-NEXT:   Section Name: .gnu.version_d
+# DSO-NEXT:   Address: 0x230
+# DSO-NEXT:   Offset: 0x230
+# DSO-NEXT:   Link: 5
+# DSO-NEXT:   Entries [
+# DSO-NEXT:     Entry {
+# DSO-NEXT:       Offset: 0x0
+# DSO-NEXT:       Rev: 1
+# DSO-NEXT:       Flags: 1
+# DSO-NEXT:       Index: 1
+# DSO-NEXT:       Cnt: 1
+# DSO-NEXT:       Hash: 146942095
+# DSO-NEXT:       Name:
+# DSO-NEXT:     }
+# DSO-NEXT:     Entry {
+# DSO-NEXT:       Offset: 0x14
+# DSO-NEXT:       Rev: 1
+# DSO-NEXT:       Flags: 0
+# DSO-NEXT:       Index: 2
+# DSO-NEXT:       Cnt: 1
+# DSO-NEXT:       Hash: 98457184
+# DSO-NEXT:       Name: LIBSAMPLE_1.0
+# DSO-NEXT:     }
+# DSO-NEXT:     Entry {
+# DSO-NEXT:       Offset: 0x28
+# DSO-NEXT:       Rev: 1
+# DSO-NEXT:       Flags: 0
+# DSO-NEXT:       Index: 4
+# DSO-NEXT:       Cnt: 1
+# DSO-NEXT:       Hash: 98456672
+# DSO-NEXT:       Name: LIBSAMPLE_3.0
+# DSO-NEXT:     }
+# DSO-NEXT:     Entry {
+# DSO-NEXT:       Offset: 0x3C
+# DSO-NEXT:       Rev: 1
+# DSO-NEXT:       Flags: 0
+# DSO-NEXT:       Index: 3
+# DSO-NEXT:       Cnt: 1
+# DSO-NEXT:       Hash: 98456416
+# DSO-NEXT:       Name: LIBSAMPLE_2.0
+# DSO-NEXT:     }
+# DSO-NEXT:   ]
+# DSO-NEXT: }
+# DSO-NEXT: SHT_GNU_verneed {
+# DSO-NEXT: }
+
+## Check that we can link agains DSO we produced.
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %S/Inputs/verdef.s -o %tmain.o
+# RUN: ld.lld %tmain.o %t.so -o %tout
+# RUN: llvm-readobj -V %tout | FileCheck --check-prefix=MAIN %s
+
+# MAIN:      Version symbols {
+# MAIN-NEXT:   Section Name: .gnu.version
+# MAIN-NEXT:   Address: 0x10228
+# MAIN-NEXT:   Offset: 0x228
+# MAIN-NEXT:   Link: 1
+# MAIN-NEXT:   Symbols [
+# MAIN-NEXT:     Symbol {
+# MAIN-NEXT:       Version: 0
+# MAIN-NEXT:       Name: @
+# MAIN-NEXT:     }
+# MAIN-NEXT:     Symbol {
+# MAIN-NEXT:       Version: 2
+# MAIN-NEXT:       Name: a@LIBSAMPLE_1.0
+# MAIN-NEXT:     }
+# MAIN-NEXT:     Symbol {
+# MAIN-NEXT:       Version: 3
+# MAIN-NEXT:       Name: b@LIBSAMPLE_2.0
+# MAIN-NEXT:     }
+# MAIN-NEXT:     Symbol {
+# MAIN-NEXT:       Version: 4
+# MAIN-NEXT:       Name: c@LIBSAMPLE_3.0
+# MAIN-NEXT:     }
+# MAIN-NEXT:   ]
+# MAIN-NEXT: }
+# MAIN-NEXT: Version definition {
+# MAIN-NEXT: }
+
+.globl a
+.type  a,@function
+a:
+retq
+
+.globl b
+.type  b,@function
+b:
+retq
+
+.globl c
+.type  c,@function
+c:
+retq