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.test
===================================================================
--- /dev/null
+++ test/ELF/compressed-debug-conflict.test
@@ -0,0 +1,181 @@
+# REQUIRES: x86
+# RUN: yaml2obj %s -o %t.o
+# RUN: not ld.lld %t.o %t.o -o %tout 2>&1 | FileCheck %s
+
+# CHECK:      error: duplicate symbol: main
+# CHECK-NEXT: >>> defined at reduced.c:2 (/tmp/reduced.c:2)
+# CHECK-NEXT: >>>
+# CHECK-NEXT: >>> defined at reduced.c:2 (/tmp/reduced.c:2)
+# CHECK-NEXT: >>>
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_386
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000010
+    Content:         5589E55031C0C745FC0000000083C4045DC3
+  - Name:            .debug_str
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x0000000000000001
+    Content:         636C616E672076657273696F6E20362E302E3020287472756E6B203331343730382920286C6C766D2F7472756E6B2033313437313529002F746D702F726564756365642E63002F746D70006D61696E00696E74006D79696E7400
+  - Name:            .debug_abbrev
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         011101250E1305030E10171B0EB44219110112060000022E00110112064018030E3A0B3B0B49133F1900000316004913030E3A0B3B0B0000042400030E3E0B0B0B000000
+  - Name:            .debug_info
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_COMPRESSED ]
+    AddressAlign:    0x0000000000000001
+    Content:         010000004E00000001000000789CF362606060610001164610C9C3800E84809809C6600C05B11899AC8124B31B54051323D80456160600373F0173
+  - Name:            .rel.debug_info
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .debug_info
+    Relocations:
+      - Offset:          0x0000000000000006
+        Symbol:          .debug_abbrev
+        Type:            R_386_32
+      - Offset:          0x000000000000000C
+        Symbol:          ''
+        Type:            R_386_32
+      - Offset:          0x0000000000000012
+        Symbol:          ''
+        Type:            R_386_32
+      - Offset:          0x0000000000000016
+        Symbol:          .debug_line
+        Type:            R_386_32
+      - Offset:          0x000000000000001A
+        Symbol:          ''
+        Type:            R_386_32
+      - Offset:          0x000000000000001E
+        Symbol:          .text
+        Type:            R_386_32
+      - Offset:          0x0000000000000027
+        Symbol:          .text
+        Type:            R_386_32
+      - Offset:          0x0000000000000031
+        Symbol:          ''
+        Type:            R_386_32
+      - Offset:          0x0000000000000040
+        Symbol:          ''
+        Type:            R_386_32
+      - Offset:          0x0000000000000047
+        Symbol:          ''
+        Type:            R_386_32
+  - Name:            .debug_ranges
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+  - Name:            .debug_macinfo
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         '00'
+  - Name:            .debug_pubnames
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         170000000200000000004E000000260000006D61696E0000000000
+  - Name:            .rel.debug_pubnames
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .debug_pubnames
+    Relocations:
+      - Offset:          0x0000000000000006
+        Symbol:          .debug_info
+        Type:            R_386_32
+  - Name:            .debug_pubtypes
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         200000000200000000004E0000003B0000006D79696E740046000000696E740000000000
+  - Name:            .rel.debug_pubtypes
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .debug_pubtypes
+    Relocations:
+      - Offset:          0x0000000000000006
+        Symbol:          .debug_info
+        Type:            R_386_32
+  - Name:            .comment
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x0000000000000001
+    Content:         00636C616E672076657273696F6E20362E302E3020287472756E6B203331343730382920286C6C766D2F7472756E6B203331343731352900
+  - Name:            .note.GNU-stack
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+  - Name:            .debug_frame
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000004
+    Content:         10000000FFFFFFFF04000400017C080C0404880114000000000000000000000012000000410E088502420D05
+  - Name:            .rel.debug_frame
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .debug_frame
+    Relocations:
+      - Offset:          0x0000000000000018
+        Symbol:          .debug_frame
+        Type:            R_386_32
+      - Offset:          0x000000000000001C
+        Symbol:          .text
+        Type:            R_386_32
+  - Name:            .debug_line
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_COMPRESSED ]
+    AddressAlign:    0x0000000000000001
+    Content:         010000006D00000001000000789CCB64606060620802928C8CBFF97881242323880344FA25B9050C2042BF28B52035B1042BC5C050949A529A9C9AA2970CD20411D4CB009A0904AC6052985580EB04132BD0680001C8172D
+  - Name:            .rel.debug_line
+    Type:            SHT_REL
+    Link:            .symtab
+    AddressAlign:    0x0000000000000004
+    Info:            .debug_line
+    Relocations:
+      - Offset:          0x000000000000005F
+        Symbol:          .text
+        Type:            R_386_32
+Symbols:
+  Local:
+    - Name:            reduced.c
+      Type:            STT_FILE
+    - Section:         .debug_str
+    - Section:         .debug_str
+      Value:           0x0000000000000037
+    - Section:         .debug_str
+      Value:           0x0000000000000046
+    - Section:         .debug_str
+      Value:           0x000000000000004B
+    - Section:         .debug_str
+      Value:           0x0000000000000050
+    - Section:         .debug_str
+      Value:           0x0000000000000054
+    - Name:            .text
+      Type:            STT_SECTION
+      Section:         .text
+    - Name:            .debug_abbrev
+      Type:            STT_SECTION
+      Section:         .debug_abbrev
+    - Name:            .debug_info
+      Type:            STT_SECTION
+      Section:         .debug_info
+    - Name:            .debug_frame
+      Type:            STT_SECTION
+      Section:         .debug_frame
+    - Name:            .debug_line
+      Type:            STT_SECTION
+      Section:         .debug_line
+  Global:
+    - Name:            main
+      Type:            STT_FUNC
+      Section:         .text
+      Size:            0x0000000000000012
+...