Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -1488,12 +1488,16 @@
   this->Entsize = Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 }
 
+// Place R_*_RELATIVE first (required by DT_REL[A]COUNT). The second key is the
+// symbol index - the locality optimizes dynamic loader performance. The third
+// key is r_offset - relative relocations ordered by r_offset facilitate
+// debugging. It also breaks ties for non-relative relocations of the same
+// symbol.
 static bool compRelocations(const DynamicReloc &A, const DynamicReloc &B) {
-  bool AIsRel = A.Type == Target->RelativeRel;
-  bool BIsRel = B.Type == Target->RelativeRel;
-  if (AIsRel != BIsRel)
-    return AIsRel;
-  return A.getSymIndex() < B.getSymIndex();
+  return std::make_tuple(A.Type != Target->RelativeRel, A.getSymIndex(),
+                         A.getOffset()) <
+         std::make_tuple(B.Type != Target->RelativeRel, B.getSymIndex(),
+                         B.getOffset());
 }
 
 template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
Index: test/ELF/combreloc.s
===================================================================
--- /dev/null
+++ test/ELF/combreloc.s
@@ -0,0 +1,47 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
+# RUN: echo 'mov aaa@gotpcrel(%rip), %rax' | llvm-mc -filetype=obj -triple=x86_64 - -o %t1.o
+
+# RUN: ld.lld -shared %t.o %t1.o -o %t.so
+# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
+# RUN: ld.lld -shared %t.o %t1.o -o %t.so -z combreloc
+# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck %s
+
+# -z combreloc is the default: sort relocations by (!IsRelative, SymIndex, r_offset).
+# and emit DT_RELACOUNT to indicate the number of relative relocations.
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
+# CHECK-NEXT:     0x3020 R_X86_64_RELATIVE - 0x3028
+# CHECK-NEXT:     0x20B0 R_X86_64_GLOB_DAT aaa 0x0
+# CHECK-NEXT:     0x3000 R_X86_64_64 aaa 0x0
+# CHECK-NEXT:     0x3018 R_X86_64_64 aaa 0x0
+# CHECK-NEXT:     0x3010 R_X86_64_64 bbb 0x0
+# CHECK-NEXT:     0x3008 R_X86_64_64 ccc 0x0
+# CHECK-NEXT:   }
+# CHECK:      DynamicSection [
+# CHECK:        RELACOUNT 1
+
+# RUN: ld.lld -z nocombreloc -shared %t.o %t1.o -o %t.so
+# RUN: llvm-readobj -r --dynamic-table %t.so | FileCheck --check-prefix=NOCOMB %s
+
+# NOCOMB:      Relocations [
+# NOCOMB-NEXT:   Section ({{.*}}) .rela.dyn {
+# NOCOMB-NEXT:     0x3000 R_X86_64_64 aaa 0x0
+# NOCOMB-NEXT:     0x3008 R_X86_64_64 ccc 0x0
+# NOCOMB-NEXT:     0x3010 R_X86_64_64 bbb 0x0
+# NOCOMB-NEXT:     0x3018 R_X86_64_64 aaa 0x0
+# NOCOMB-NEXT:     0x3020 R_X86_64_RELATIVE - 0x3028
+# NOCOMB-NEXT:     0x20A0 R_X86_64_GLOB_DAT aaa 0x0
+# NOCOMB-NEXT:   }
+# NOCOMB:      DynamicSection [
+# NOCOMB-NOT:    RELACOUNT
+
+.data
+ .quad aaa
+ .quad ccc
+ .quad bbb
+ .quad aaa
+ .quad relative
+relative:
Index: test/ELF/combrelocs.s
===================================================================
--- test/ELF/combrelocs.s
+++ /dev/null
@@ -1,95 +0,0 @@
-# REQUIRES: x86
-
-# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
-# RUN: ld.lld -shared %t.o -o %t.out
-# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | FileCheck %s
-
-# RUN: ld.lld -shared %t.o -o %t.out -z combreloc
-# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | FileCheck %s
-
-# CHECK:      Relocations [
-# CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
-# CHECK-NEXT:     Relocation {
-# CHECK-NEXT:       Offset: 0x2000
-# CHECK-NEXT:       Type: R_X86_64_64
-# CHECK-NEXT:       Symbol: aaa (1)
-# CHECK-NEXT:       Addend: 0x0
-# CHECK-NEXT:     }
-# CHECK-NEXT:     Relocation {
-# CHECK-NEXT:       Offset: 0x2018
-# CHECK-NEXT:       Type: R_X86_64_64
-# CHECK-NEXT:       Symbol: aaa (1)
-# CHECK-NEXT:       Addend: 0x0
-# CHECK-NEXT:     }
-# CHECK-NEXT:     Relocation {
-# CHECK-NEXT:       Offset: 0x2010
-# CHECK-NEXT:       Type: R_X86_64_64
-# CHECK-NEXT:       Symbol: bbb (2)
-# CHECK-NEXT:       Addend: 0x0
-# CHECK-NEXT:     }
-# CHECK-NEXT:     Relocation {
-# CHECK-NEXT:       Offset: 0x2008
-# CHECK-NEXT:       Type: R_X86_64_64
-# CHECK-NEXT:       Symbol: ccc (3)
-# CHECK-NEXT:       Addend: 0x0
-# CHECK-NEXT:     }
-# CHECK-NEXT:     Relocation {
-# CHECK-NEXT:       Offset: 0x2020
-# CHECK-NEXT:       Type: R_X86_64_64
-# CHECK-NEXT:       Symbol: ddd (4)
-# CHECK-NEXT:       Addend: 0x0
-# CHECK-NEXT:     }
-# CHECK-NEXT:   }
-# CHECK-NEXT: ]
-# CHECK:      DynamicSection [
-# CHECK-NEXT:   Tag
-# CHECK-NOT:    RELACOUNT
-
-# RUN: ld.lld -z nocombreloc -shared %t.o -o %t.out
-# RUN: llvm-readobj -r --expand-relocs --dynamic-table %t.out | \
-# RUN:    FileCheck --check-prefix=NOCOMB %s
-
-# NOCOMB:      Relocations [
-# NOCOMB-NEXT:    Section ({{.*}}) .rela.dyn {
-# NOCOMB-NEXT:     Relocation {
-# NOCOMB-NEXT:       Offset: 0x2000
-# NOCOMB-NEXT:       Type: R_X86_64_64
-# NOCOMB-NEXT:       Symbol: aaa (1)
-# NOCOMB-NEXT:       Addend: 0x0
-# NOCOMB-NEXT:     }
-# NOCOMB-NEXT:     Relocation {
-# NOCOMB-NEXT:       Offset: 0x2008
-# NOCOMB-NEXT:       Type: R_X86_64_64
-# NOCOMB-NEXT:       Symbol: ccc (3)
-# NOCOMB-NEXT:       Addend: 0x0
-# NOCOMB-NEXT:     }
-# NOCOMB-NEXT:     Relocation {
-# NOCOMB-NEXT:       Offset: 0x2010
-# NOCOMB-NEXT:       Type: R_X86_64_64
-# NOCOMB-NEXT:       Symbol: bbb (2)
-# NOCOMB-NEXT:       Addend: 0x0
-# NOCOMB-NEXT:     }
-# NOCOMB-NEXT:     Relocation {
-# NOCOMB-NEXT:       Offset: 0x2018
-# NOCOMB-NEXT:       Type: R_X86_64_64
-# NOCOMB-NEXT:       Symbol: aaa (1)
-# NOCOMB-NEXT:       Addend: 0x0
-# NOCOMB-NEXT:     }
-# NOCOMB-NEXT:     Relocation {
-# NOCOMB-NEXT:       Offset: 0x2020
-# NOCOMB-NEXT:       Type: R_X86_64_64
-# NOCOMB-NEXT:       Symbol: ddd (4)
-# NOCOMB-NEXT:       Addend: 0x0
-# NOCOMB-NEXT:     }
-# NOCOMB-NEXT:   }
-# NOCOMB-NEXT:  ]
-# NOCOMB:      DynamicSection [
-# NOCOMB-NEXT:   Tag
-# NOCOMB-NOT:    RELACOUNT
-
-.data
- .quad aaa
- .quad ccc
- .quad bbb
- .quad aaa
- .quad ddd
Index: test/ELF/i386-got-and-copy.s
===================================================================
--- test/ELF/i386-got-and-copy.s
+++ test/ELF/i386-got-and-copy.s
@@ -14,8 +14,8 @@
 
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section (4) .rel.dyn {
-# CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_COPY foo
 # CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_GLOB_DAT foo
+# CHECK-NEXT:     0x{{[0-9A-F]+}} R_386_COPY foo
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]