Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -427,6 +427,16 @@
   return nullptr;
 }
 
+static void addMergeableStringSection(OutputSection *Sec,
+                                      InputSectionBase *IS) {
+  assert(Config->Relocatable);
+  if (Sec->Entsize != IS->Entsize)
+    Sec->Flags &= ~SHF_MERGE;
+  if (!(Sec->Flags & SHF_MERGE))
+    IS->Flags &= ~SHF_MERGE;
+  Sec->addSection(cast<InputSection>(IS));
+}
+
 static OutputSection *createSection(InputSectionBase *IS,
                                     StringRef OutsecName) {
   OutputSection *Sec = Script->createOutputSection(OutsecName, "<internal>");
@@ -466,11 +476,23 @@
     return Out->RelocationSection;
   }
 
-  // When control reaches here, mergeable sections have already been
-  // merged except the -r case. If that's the case, we do not combine them
-  // and let final link to handle this optimization.
-  if (Config->Relocatable && (IS->Flags & SHF_MERGE))
-    return createSection(IS, OutsecName);
+  // When control reaches here, mergeable sections have already been merged
+  // except the -r case. If that's the case, we do not really want to care about
+  // merging sections, leaving this task for final link. But unfortunately we
+  // still need to do that for .debug_str sections, because different tools
+  // like dwarfdump expects to see single instance in the output. To handle this
+  // case we merge string sections and just drop SHF_MERGE optimization flag if
+  // entry sizes of input and output sections are different. That normally
+  // should not happen as entry size usually is always 1 for strings sections.
+  if (Config->Relocatable && (IS->Flags & SHF_MERGE)) {
+    OutputSection *&Sec = Map[OutsecName];
+    if (!Sec || !(IS->Flags & SHF_STRINGS)) {
+      Sec = createSection(IS, OutsecName);
+      return Sec;
+    }
+    addMergeableStringSection(Sec, IS);
+    return nullptr;
+  }
 
   //  The ELF spec just says
   // ----------------------------------------------------------------
Index: test/ELF/relocatable-mergeable.s
===================================================================
--- test/ELF/relocatable-mergeable.s
+++ test/ELF/relocatable-mergeable.s
@@ -0,0 +1,67 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
+# RUN: ld.lld %t1 -o %t2 -r
+# RUN: llvm-readobj -sections %t2 | FileCheck %s
+
+## Check we merged 2 .strings sections together and dropped SHF_MERGE flag
+## because they have different sh_entsize. Check we created separate output
+## section for each non-string mergeable input and keeped SHF_MERGE.
+
+# CHECK:      Section {
+# CHECK:        Index:
+# CHECK:        Name: .strings
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_STRINGS
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address:
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size: 8
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize: 3
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .nonstrings
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_MERGE
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address:
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size: 4
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize: 2
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .nonstrings
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_MERGE
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address:
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size: 4
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize: 4
+# CHECK-NEXT: }
+
+.section .strings,"MS",@progbits,1,unique,10
+.asciz "foo"
+
+.section .nonstrings,"M",@progbits,2,unique,20
+.long 11
+
+.section .strings,"MS",@progbits,3,unique,30
+.asciz "bar"
+
+.section .nonstrings,"M",@progbits,4,unique,40
+.long 22