Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -104,6 +104,7 @@
   bool Bsymbolic;
   bool BsymbolicFunctions;
   bool ColorDiagnostics = false;
+  bool CompressDebugSections;
   bool DefineCommon;
   bool Demangle = true;
   bool DisableVerify;
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -45,6 +45,7 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compression.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/TargetSelect.h"
@@ -551,12 +552,26 @@
   return Ret;
 }
 
+static bool getCompressDebugSections(opt::InputArgList &Args) {
+  if (auto *Arg = Args.getLastArg(OPT_compress_debug_sections)) {
+    StringRef S = Arg->getValue();
+    if (S == "none")
+      return false;
+    if (S == "zlib" || S == "zlib-gabi")
+      return zlib::isAvailable();
+    // We support only default zlib compression style now.
+    error("unknown --compress-debug-sections value: " + S);
+  }
+  return false;
+}
+
 // Initializes Config members by the command line options.
 void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->AllowMultipleDefinition = Args.hasArg(OPT_allow_multiple_definition);
   Config->AuxiliaryList = getArgs(Args, OPT_auxiliary);
   Config->Bsymbolic = Args.hasArg(OPT_Bsymbolic);
   Config->BsymbolicFunctions = Args.hasArg(OPT_Bsymbolic_functions);
+  Config->CompressDebugSections = getCompressDebugSections(Args);
   Config->DefineCommon = getArg(Args, OPT_define_common, OPT_no_define_common,
                                 !Args.hasArg(OPT_relocatable));
   Config->Demangle = getArg(Args, OPT_demangle, OPT_no_demangle, true);
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -22,6 +22,9 @@
 
 def build_id_eq: J<"build-id=">, HelpText<"Generate build ID note">;
 
+def compress_debug_sections : Joined<["--"], "compress-debug-sections=">,
+  HelpText<"Compresses DWARF debug sections">;
+
 def L: JoinedOrSeparate<["-"], "L">, MetaVarName<"<dir>">,
   HelpText<"Add a directory to the library search path">;
 
Index: ELF/OutputSections.h
===================================================================
--- ELF/OutputSections.h
+++ ELF/OutputSections.h
@@ -87,6 +87,13 @@
   void assignOffsets();
   std::vector<InputSection *> Sections;
 
+  // Contains compressed relocated content, used for implementation of
+  // --compress-debug-sections option.
+  std::vector<uint8_t> CompressedData;
+
+  // Size of decompressed data. Only has meaning if compression enabled.
+  size_t DecompressedSize;
+
   // Location in the output buffer.
   uint8_t *Loc = nullptr;
 };
Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -16,6 +16,7 @@
 #include "SyntheticSections.h"
 #include "Target.h"
 #include "Threads.h"
+#include "llvm/Support/Compression.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/MathExtras.h"
@@ -67,7 +68,13 @@
 OutputSection::OutputSection(StringRef Name, uint32_t Type, uint64_t Flags)
     : SectionBase(Output, Name, Flags, /*Entsize*/ 0, /*Alignment*/ 1, Type,
                   /*Info*/ 0,
-                  /*Link*/ 0) {}
+                  /*Link*/ 0) {
+  if (!Config->CompressDebugSections || !Name.startswith(".debug"))
+    return;
+  // SHF_COMPRESSED can not be used in conjunction with SHF_ALLOC flag.
+  if (!(Flags & SHF_ALLOC))
+    this->Flags |= SHF_COMPRESSED;
+}
 
 static bool compareByFilePosition(InputSection *A, InputSection *B) {
   // Synthetic doesn't have link order dependecy, stable_sort will keep it last
@@ -96,6 +103,33 @@
       this->Link = D->OutSec->SectionIndex;
   }
 
+  if (this->Flags & SHF_COMPRESSED) {
+    assignOffsets();
+
+    std::unique_ptr<zlib::StreamCompression> Compressor =
+        check(zlib::StreamCompression::create(1024));
+    for (size_t I = 0, E = Sections.size(); I != E; ++I) {
+      InputSection *Sec = Sections[I];
+      size_t Size;
+      if (I == E - 1)
+        Size = Sec->OutSecOff + Sec->getSize();
+      else
+        Size = Sections[I + 1]->OutSecOff - Sec->OutSecOff;
+
+      std::vector<uint8_t> RelData(Size);
+      Sec->relocate<ELFT>(RelData.data(), RelData.data() + Size);
+
+      Compressor->compress(RelData, I == E - 1, [&](ArrayRef<uint8_t> Piece) {
+        CompressedData.insert(CompressedData.end(), Piece.begin(), Piece.end());
+      });
+    }
+
+    this->DecompressedSize = this->Size;
+    this->Size = this->CompressedData.size() + Config->Is64
+                     ? sizeof(Elf64_Chdr)
+                     : sizeof(Elf32_Chdr);
+  }
+
   uint32_t Type = this->Type;
   if (!Config->CopyRelocs || (Type != SHT_RELA && Type != SHT_REL))
     return;
@@ -247,9 +281,40 @@
   return 0;
 }
 
+static void writeCompressed(uint8_t *Buf, ArrayRef<uint8_t> Data,
+                            size_t OrigSize, uint32_t OrigAlignment) {
+  llvm::support::endianness E = Config->Endianness;
+  write32(Buf, ELFCOMPRESS_ZLIB, E);
+  Buf += 4;
+
+  if (Config->Is64) {
+    Buf += sizeof(Elf64_Word); // Skip ch_reserved field.
+    write64(Buf, OrigSize, E);
+    Buf += sizeof(Elf64_Xword);
+    write64(Buf, OrigAlignment, E);
+    Buf += sizeof(Elf64_Xword);
+  } else {
+    write32(Buf, OrigSize, E);
+    Buf += sizeof(Elf32_Word);
+    write32(Buf, OrigAlignment, E);
+    Buf += sizeof(Elf32_Word);
+  }
+
+  memcpy(Buf, Data.data(), Data.size());
+}
+
 template <class ELFT> void OutputSection::writeTo(uint8_t *Buf) {
   Loc = Buf;
 
+  // If we have compressed output section here, we should write
+  // header and data that we already prepared in finilize().
+  // Sections compression header format is explaned here:
+  // https://docs.oracle.com/cd/E53394_01/html/E54813/section_compression.html
+  if (!CompressedData.empty()) {
+    writeCompressed(Buf, CompressedData, DecompressedSize, Alignment);
+    return;
+  }
+
   uint32_t Filler = getFill();
 
   // Write leading padding.
Index: test/ELF/compress-debug-sections.s
===================================================================
--- test/ELF/compress-debug-sections.s
+++ test/ELF/compress-debug-sections.s
@@ -0,0 +1,54 @@
+# REQUIRES: x86
+# REQUIRES: zlib
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+
+# RUN: ld.lld %t.o -o %t1 --compress-debug-sections=zlib
+# RUN: llvm-objdump -s %t1 | FileCheck %s --check-prefix=ZLIBCONTENT
+# RUN: llvm-readobj -s %t1 | FileCheck %s --check-prefix=ZLIBFLAGS
+# RUN: ld.lld %t.o -o %t2 --compress-debug-sections=zlib-gabi
+# RUN: llvm-objdump -s %t2 | FileCheck %s --check-prefix=ZLIBCONTENT
+# RUN: llvm-readobj -s %t2 | FileCheck %s --check-prefix=ZLIBFLAGS
+
+# ZLIBCONTENT:     Contents of section .debug_str:
+# ZLIBCONTENT-NEXT:  0000 01000000 00000000 38000000 00000000
+# ZLIBCONTENT-NEXT:  0010 01000000 00000000 789c6360 200f0000
+# ZLIBCONTENT-NEXT:  0020 00380001
+# ZLIBFLAGS:       Section {
+# ZLIBFLAGS:         Index:
+# ZLIBFLAGS:         Name: .debug_str
+# ZLIBFLAGS-NEXT:    Type: SHT_PROGBITS
+# ZLIBFLAGS-NEXT:    Flags [
+# ZLIBFLAGS-NEXT:      SHF_COMPRESSED
+# ZLIBFLAGS-NEXT:      SHF_MERGE
+# ZLIBFLAGS-NEXT:      SHF_STRINGS
+# ZLIBFLAGS-NEXT:    ]
+# ZLIBFLAGS-NEXT:    Address:
+# ZLIBFLAGS-NEXT:    Offset:
+# ZLIBFLAGS-NEXT:    Size: 36
+
+# RUN: ld.lld %t.o -o %t3 --compress-debug-sections=none
+# RUN: llvm-objdump -s %t3 | FileCheck %s --check-prefix=CONTENT
+# RUN: llvm-readobj -s %t3 | FileCheck %s --check-prefix=FLAGS
+
+# CONTENT:      Contents of section .debug_str:
+# CONTENT-NEXT:  0000 41414141 41414141 41414141 41414141  AAAAAAAAAAAAAAAA
+# CONTENT-NEXT:  0010 41414141 41414141 41414100 42424242  AAAAAAAAAAA.BBBB
+# CONTENT-NEXT:  0020 42424242 42424242 42424242 42424242  BBBBBBBBBBBBBBBB
+# CONTENT-NEXT:  0030 42424242 42424200                    BBBBBBB.
+# FLAGS:        Section {
+# FLAGS:          Index:
+# FLAGS:          Name: .debug_str
+# FLAGS-NEXT:     Type: SHT_PROGBITS
+# FLAGS-NEXT:     Flags [
+# FLAGS-NEXT:       SHF_MERGE
+# FLAGS-NEXT:       SHF_STRINGS
+# FLAGS-NEXT:     ]
+# FLAGS-NEXT:     Address: 0x0
+# FLAGS-NEXT:     Offset: 0x1000
+# FLAGS-NEXT:     Size: 56
+
+.section .debug_str,"MS",@progbits,1
+.Linfo_string0:
+  .asciz "AAAAAAAAAAAAAAAAAAAAAAAAAAA"
+.Linfo_string1:
+  .asciz "BBBBBBBBBBBBBBBBBBBBBBBBBBB"