Index: ELF/MapFile.cpp
===================================================================
--- ELF/MapFile.cpp
+++ ELF/MapFile.cpp
@@ -27,9 +27,11 @@
 #include "SymbolTable.h"
 #include "SyntheticSections.h"
 #include "lld/Common/Threads.h"
+#include "llvm/BinaryFormat/ELF.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
+using namespace llvm::ELF;
 using namespace llvm::object;
 
 using namespace lld;
@@ -132,6 +134,15 @@
         OS << indent(1) << toString(IS) << '\n';
         for (Defined *Sym : SectionSyms[IS])
           OS << SymStr[Sym] << '\n';
+
+        // Dump synthetic mergeable sections layout.
+        if (!isa<SyntheticSection>(IS) || !(IS->Flags & SHF_MERGE))
+          continue;
+        MergeSyntheticSection *MS = static_cast<MergeSyntheticSection *>(IS);
+        for (MergeInputSection *Sec : MS->getSections()) {
+          writeHeader(OS, 0, Sec->getSize(), Sec->Alignment);
+          OS << indent(2) << toString(Sec) << '\n';
+        }
       }
     }
   }
Index: ELF/SyntheticSections.h
===================================================================
--- ELF/SyntheticSections.h
+++ ELF/SyntheticSections.h
@@ -682,6 +682,8 @@
 public:
   void addSection(MergeInputSection *MS);
 
+  ArrayRef<MergeInputSection *> getSections() { return Sections; }
+
 protected:
   MergeSyntheticSection(StringRef Name, uint32_t Type, uint64_t Flags,
                         uint32_t Alignment)
Index: test/ELF/Inputs/map-file2.s
===================================================================
--- test/ELF/Inputs/map-file2.s
+++ test/ELF/Inputs/map-file2.s
@@ -6,3 +6,7 @@
 .section .text.zed,"ax",@progbits
 .global zed
 zed:
+.section .strings,"MS",@progbits,1
+.align 2
+.asciz "AAA"
+.asciz "AAA"
Index: test/ELF/map-file.s
===================================================================
--- test/ELF/map-file.s
+++ test/ELF/map-file.s
@@ -29,6 +29,9 @@
 abs = 0xAB5
 labs = 0x1AB5
 
+.section .strings,"MS",@progbits,1
+.asciz "AAA"
+
 // CHECK:      Address          Size             Align Out     In      Symbol
 // CHECK-NEXT: 0000000000200158 0000000000000030     8 .eh_frame
 // CHECK-NEXT: 0000000000200158 0000000000000030     8         <internal>:(.eh_frame)
@@ -49,12 +52,18 @@
 // CHECK-NEXT: 0000000000202000 0000000000000004    16 .bss
 // CHECK-NEXT: 0000000000202000 0000000000000004    16         {{.*}}{{/|\\}}map-file.s.tmp1.o:(COMMON)
 // CHECK-NEXT: 0000000000202000 0000000000000004     0                 common
+// CHECK-NEXT: 0000000000000000 0000000000000008     2 .strings
+// CHECK-NEXT: 0000000000000000 0000000000000004     1         <internal>:(.strings)
+// CHECK-NEXT: 0000000000000000 0000000000000004     1                 {{.*}}{{/|\\}}map-file.s.tmp1.o:(.strings)
+// CHECK-NEXT: 0000000000000004 0000000000000004     2         <internal>:(.strings)
+// CHECK-NEXT: 0000000000000000 0000000000000008     2                 {{.*}}{{/|\\}}map-file.s.tmp2.o:(.strings)
 // CHECK-NEXT: 0000000000000000 0000000000000008     1 .comment
 // CHECK-NEXT: 0000000000000000 0000000000000008     1         <internal>:(.comment)
+// CHECK-NEXT: 0000000000000000 0000000000000008     1                 <internal>:(.comment)
 // CHECK-NEXT: 0000000000000000 0000000000000120     8 .symtab
 // CHECK-NEXT: 0000000000000000 0000000000000120     8         <internal>:(.symtab)
-// CHECK-NEXT: 0000000000000000 0000000000000039     1 .shstrtab
-// CHECK-NEXT: 0000000000000000 0000000000000039     1         <internal>:(.shstrtab)
+// CHECK-NEXT: 0000000000000000 0000000000000042     1 .shstrtab
+// CHECK-NEXT: 0000000000000000 0000000000000042     1         <internal>:(.shstrtab)
 // CHECK-NEXT: 0000000000000000 0000000000000038     1 .strtab
 // CHECK-NEXT: 0000000000000000 0000000000000038     1         <internal>:(.strtab)