Index: ELF/InputSection.h
===================================================================
--- ELF/InputSection.h
+++ ELF/InputSection.h
@@ -127,6 +127,11 @@
 
   void relocate(uint8_t *Buf, uint8_t *BufEnd);
   std::vector<Relocation> Relocations;
+
+private:
+  void maybeUnpackContent();
+
+  SmallVector<char, 0> Unpacked;
 };
 
 template <class ELFT> InputSectionBase<ELFT> InputSectionBase<ELFT>::Discarded;
Index: ELF/InputSection.cpp
===================================================================
--- ELF/InputSection.cpp
+++ ELF/InputSection.cpp
@@ -14,6 +14,7 @@
 #include "OutputSections.h"
 #include "Target.h"
 
+#include "llvm/Support/Compression.h"
 #include "llvm/Support/Endian.h"
 
 using namespace llvm;
@@ -25,6 +26,28 @@
 using namespace lld::elf;
 
 template <class ELFT>
+void InputSectionBase<ELFT>::maybeUnpackContent() {
+  const endianness E = ELFT::TargetEndianness;
+  if (!(Header->sh_flags & SHF_COMPRESSED))
+    return;
+  if (!zlib::isAvailable())
+    fatal("build lld with zlib to enable compressed sections support");
+
+  ArrayRef<uint8_t> Data = getSectionData();
+  if (read32<E>(Data.data()) != ELFCOMPRESS_ZLIB)
+    fatal("unsupported elf compression type");
+
+  size_t UnpackedSize =
+      read<size_t, E>(ELFT::Is64Bits ? (Data.data() + sizeof(Elf64_Word) * 2)
+                                     : (Data.data() + sizeof(Elf32_Word)));
+
+  size_t HdrSize = ELFT::Is64Bits ? sizeof(Elf64_Chdr) : sizeof(Elf32_Chdr);
+  StringRef Buf((const char *)Data.data() + HdrSize, Data.size() - HdrSize);
+  if (zlib::uncompress(Buf, Unpacked, UnpackedSize) != zlib::StatusOK)
+    fatal("error uncompressing section");
+}
+
+template <class ELFT>
 InputSectionBase<ELFT>::InputSectionBase(elf::ObjectFile<ELFT> *File,
                                          const Elf_Shdr *Header,
                                          Kind SectionKind)
@@ -36,6 +59,8 @@
   // The ELF spec states that a value of 0 means the section has
   // no alignment constraits.
   Align = std::max<uintX_t>(Header->sh_addralign, 1);
+
+  maybeUnpackContent();
 }
 
 template <class ELFT> size_t InputSectionBase<ELFT>::getSize() const {
@@ -51,6 +76,8 @@
 
 template <class ELFT>
 ArrayRef<uint8_t> InputSectionBase<ELFT>::getSectionData() const {
+  if (!Unpacked.empty())
+    return ArrayRef<uint8_t>((const uint8_t *)Unpacked.data(), Unpacked.size());
   return check(this->File->getObj().getSectionContents(this->Header));
 }
 
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1192,6 +1192,7 @@
                                       StringRef OutsecName) {
   const Elf_Shdr *H = C->getSectionHdr();
   uintX_t Flags = H->sh_flags & ~SHF_GROUP;
+  Flags &= ~SHF_COMPRESSED;
 
   // For SHF_MERGE we create different output sections for each alignment.
   // This makes each output section simple and keeps a single level mapping from
Index: test/ELF/compressed-debug.s
===================================================================
--- test/ELF/compressed-debug.s
+++ test/ELF/compressed-debug.s
@@ -0,0 +1,67 @@
+## zlib support is disabled under windows now (https://llvm.org/bugs/show_bug.cgi?id=19403).
+## So this test requires *nix to run.
+
+# REQUIRES: shell
+# REQUIRES: x86
+
+## Test uses pre-generated object file. That is because llvm-mc does not support zlib compressed
+## sections in not gnu style at this moment. lld does not and probably will not support zlib-gnu
+## inputs as them are depricated in binutils. Instruction how to build the object input is below:
+##
+## Use the following compressed-debug.s file:
+##
+##.section .debug_str,"MS",@progbits,1
+##.LASF2:
+## .string "short unsigned int"
+##.LASF3:
+## .string "unsigned int"
+##.LASF0:
+## .string "long unsigned int"
+##.LASF8:
+## .string "char"
+##.LASF1:
+## .string "unsigned char"
+##
+## Generate the object, use objcopy tool to compress the debug sections:
+## llvm-mc -filetype=obj -triple=x86_64-pc-linux compressed-debug.s -o compressed-debug-tmp.o
+## objcopy --compress-debug-sections=zlib compressed-debug-tmp.o compressed-debug.o
+
+# RUN: llvm-readobj -sections %S/Inputs/compressed-debug.o | FileCheck -check-prefix=PACKED %s
+# PACKED:      Section {
+# PACKED:        Index: 2
+# PACKED:        Name: .debug_str
+# PACKED-NEXT:   Type: SHT_PROGBITS
+# PACKED-NEXT:   Flags [
+# PACKED-NEXT:     SHF_MERGE (0x10)
+# PACKED-NEXT:     SHF_STRINGS (0x20)
+# PACKED-NEXT:     0x800
+# PACKED-NEXT:   ]
+# PACKED-NEXT:   Address: 0x0
+# PACKED-NEXT:   Offset: 0x40
+# PACKED-NEXT:   Size: 66
+# PACKED-NEXT:   Link: 0
+# PACKED-NEXT:   Info: 0
+# PACKED-NEXT:   AddressAlignment: 1
+# PACKED-NEXT:   EntrySize: 1
+# PACKED-NEXT: }
+
+# RUN: ld.lld %S/Inputs/compressed-debug.o -o %t.so -shared
+# RUN: llvm-readobj -sections %t.so | FileCheck -check-prefix=UNPACKED %s
+
+## Check that section is decompressed and compression flag is removed.
+# UNPACKED:      Section {
+# UNPACKED:        Index: 6
+# UNPACKED:        Name: .debug_str
+# UNPACKED-NEXT:   Type: SHT_PROGBITS
+# UNPACKED-NEXT:   Flags [
+# UNPACKED-NEXT:     SHF_MERGE (0x10)
+# UNPACKED-NEXT:     SHF_STRINGS (0x20)
+# UNPACKED-NEXT:   ]
+# UNPACKED-NEXT:   Address: 0x0
+# UNPACKED-NEXT:   Offset: 0x1060
+# UNPACKED-NEXT:   Size: 69
+# UNPACKED-NEXT:   Link: 0
+# UNPACKED-NEXT:   Info: 0
+# UNPACKED-NEXT:   AddressAlignment: 1
+# UNPACKED-NEXT:   EntrySize: 1
+# UNPACKED-NEXT: }