Index: ELF/GdbIndex.cpp
===================================================================
--- ELF/GdbIndex.cpp
+++ ELF/GdbIndex.cpp
@@ -17,6 +17,7 @@
 #include "GdbIndex.h"
 #include "Memory.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugPubTable.h"
+#include "llvm/Object/Decompressor.h"
 #include "llvm/Object/ELFObjectFile.h"
 
 using namespace llvm;
@@ -33,6 +34,8 @@
                                  .Case(".debug_ranges", &RangeSection)
                                  .Case(".debug_line", &LineSection)
                                  .Default(nullptr)) {
+      if (Decompressor::isCompressedELFSection(Sec->Flags, Sec->Name))
+        Sec->uncompress();
       M->Data = toStringRef(Sec->Data);
       M->Sec = Sec;
       continue;
Index: test/ELF/compressed-debug-conflict.s
===================================================================
--- /dev/null
+++ test/ELF/compressed-debug-conflict.s
@@ -0,0 +1,29 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple i686-linux-gnu -compress-debug-sections=zlib %s -o %t.o
+# RUN: llvm-readobj -sections %t.o | FileCheck -check-prefix=OBJ %s
+# RUN: not ld.lld %t.o %t.o -o %tout 2>&1 | FileCheck -check-prefix=ERROR %s
+
+# OBJ:      Sections [
+# OBJ:        Section {
+# OBJ:          Index: 3
+# OBJ-NEXT:     Name: .debug_line (16)
+# OBJ-NEXT:     Type: SHT_PROGBITS (0x1)
+# OBJ-NEXT:     Flags [ (0x800)
+# OBJ-NEXT:       SHF_COMPRESSED (0x800)
+# OBJ-NEXT:     ]
+
+# ERROR:      error: duplicate symbol: main
+# ERROR-NEXT: >>> defined at reduced.c:2 (/tmp/reduced.c:2)
+# ERROR-NEXT: >>>
+# ERROR-NEXT: >>> defined at reduced.c:2 (/tmp/reduced.c:2)
+# ERROR-NEXT: >>>
+
+	.text
+	.file	"reduced.c"
+	.globl	main
+main:
+	.file	1 "/tmp" "reduced.c"
+	.loc	1 2 0
+	xorl	%eax, %eax
+	retl
+	.file	2 "/tmp/repeat/repeat/repeat/repeat" "repeat.h"