Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -54,6 +54,24 @@
   error("Unknown emulation: " + S);
 }
 
+static StringRef getDefaultInterp() {
+  switch (Config->EMachine) {
+  case EM_386:
+    return "/lib/ld-linux-x86-64.so.2";
+  case EM_AARCH64:
+    return "/lib/ld-linux-aarch64.so.1";
+  case EM_PPC:
+    return "/lib/ld.so.1";
+  case EM_PPC64:
+    return "/lib64/ld64.so.1";
+  case EM_X86_64:
+    return "/lib64/ld-linux-x86-64.so.2";
+  }
+  // No interpreter specified.
+  // Assumes that it is taken from commandline.
+  return "";
+}
+
 // Opens and parses a file. Path has to be resolved already.
 // Newly created memory buffers are owned by this driver.
 void LinkerDriver::addFile(StringRef Path) {
@@ -146,7 +164,6 @@
   Config->Shared = Args.hasArg(OPT_shared);
   Config->Verbose = Args.hasArg(OPT_verbose);
 
-  Config->DynamicLinker = getString(Args, OPT_dynamic_linker);
   Config->Entry = getString(Args, OPT_entry);
   Config->Fini = getString(Args, OPT_fini, "_fini");
   Config->Init = getString(Args, OPT_init, "_init");
@@ -196,6 +213,9 @@
   SymbolTable<ELFT> Symtab;
   Target.reset(createTarget());
 
+  Config->DynamicLinker =
+      getString(Args, OPT_dynamic_linker, getDefaultInterp());
+
   if (!Config->Shared) {
     // Add entry symbol.
     if (Config->Entry.empty())
Index: test/elf2/dynamic-reloc.s
===================================================================
--- test/elf2/dynamic-reloc.s
+++ test/elf2/dynamic-reloc.s
@@ -6,7 +6,7 @@
 // RUN: llvm-readobj -dynamic-table -r --expand-relocs -s %t | FileCheck %s
 // REQUIRES: x86
 
-// CHECK:      Index: 1
+// CHECK:      Index: 2
 // CHECK-NEXT: Name: .dynsym
 
 // CHECK:      Name: .rela.dyn
@@ -17,7 +17,7 @@
 // CHECK-NEXT: Address: [[RELAADDR:.*]]
 // CHECK-NEXT: Offset:
 // CHECK-NEXT: Size: [[RELASIZE:.*]]
-// CHECK-NEXT: Link: 1
+// CHECK-NEXT: Link: 2
 // CHECK-NEXT: Info: 0
 // CHECK-NEXT: AddressAlignment: 8
 // CHECK-NEXT: EntrySize: 24
Index: test/elf2/interp.s
===================================================================
--- test/elf2/interp.s
+++ test/elf2/interp.s
@@ -0,0 +1,61 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=i686-unknown-linux %s -o %t86.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t64.o
+
+# RUN: ld.lld2 -shared %t86.o -o %t.so
+# RUN: ld.lld2 %t86.o %t.so -o %t
+# RUN: llvm-readobj --program-headers --dynamic-table -t -s -dyn-symbols -section-data -hash-table %t | FileCheck -check-prefix=CHECK_X86 %s
+
+# RUN: ld.lld2 -shared %t64.o -o %t.so
+# RUN: ld.lld2 %t64.o %t.so -o %t
+# RUN: llvm-readobj --program-headers --dynamic-table -t -s -dyn-symbols -section-data -hash-table %t | FileCheck -check-prefix=CHECK_X64 %s
+
+# RUN: ld.lld2 %t64.o %t.so -dynamic-linker /aaa/bbb -o %t
+# RUN: llvm-readobj --program-headers --dynamic-table -t -s -dyn-symbols -section-data -hash-table %t | FileCheck -check-prefix=CHECK_AAABBB %s
+
+# RUN: ld.lld2 %t64.o -o %t
+# RUN: llvm-readobj --program-headers --dynamic-table -t -s -dyn-symbols -section-data -hash-table %t | FileCheck -check-prefix=CHECK_NO %s
+
+# CHECK_X86:      Name: .interp
+# CHECK_X86-NEXT: Type: SHT_PROGBITS
+# CHECK_X86-NEXT: Flags [
+# CHECK_X86-NEXT:   SHF_ALLOC
+# CHECK_X86-NEXT: ]
+# CHECK_X86-NEXT: Address: 0x100D4
+# CHECK_X86-NEXT: Offset: 0xD4
+# CHECK_X86-NEXT: Size: 26
+# CHECK_X86-NEXT: Link: 0
+# CHECK_X86-NEXT: Info: 0
+# CHECK_X86-NEXT: AddressAlignment: 1
+# CHECK_X86-NEXT: EntrySize: 0
+# CHECK_X86-NEXT: SectionData (
+# CHECK_X86-NEXT:   0000: 2F6C6962 2F6C642D 6C696E75 782D7838  |/lib/ld-linux-x8|
+# CHECK_X86-NEXT:   0010: 362D3634 2E736F2E 3200               |6-64.so.2.|
+# CHECK_X86-NEXT: )
+
+# CHECK_X64:      Name: .interp
+# CHECK_X64-NEXT: Type: SHT_PROGBITS
+# CHECK_X64-NEXT: Flags [
+# CHECK_X64-NEXT:   SHF_ALLOC
+# CHECK_X64-NEXT: ]
+# CHECK_X64-NEXT: Address: 0x10158
+# CHECK_X64-NEXT: Offset: 0x158
+# CHECK_X64-NEXT: Size: 28
+# CHECK_X64-NEXT: Link: 0
+# CHECK_X64-NEXT: Info: 0
+# CHECK_X64-NEXT: AddressAlignment: 1
+# CHECK_X64-NEXT: EntrySize: 0
+# CHECK_X64-NEXT: SectionData (
+# CHECK_X64-NEXT:   0000: 2F6C6962 36342F6C 642D6C69 6E75782D  |/lib64/ld-linux-|
+# CHECK_X64-NEXT:   0010: 7838362D 36342E73 6F2E3200           |x86-64.so.2.|
+# CHECK_X64-NEXT: )
+
+# CHECK_AAABBB:      Name: .interp
+# CHECK_AAABBB:      SectionData (
+# CHECK_AAABBB-NEXT:   0000: 2F616161 2F626262 00                 |/aaa/bbb.|
+# CHECK_AAABBB-NEXT: )
+
+# CHECK_NO-NOT: Name: .interp
+
+.global _start
+_start:
Index: test/elf2/relocation.s
===================================================================
--- test/elf2/relocation.s
+++ test/elf2/relocation.s
@@ -86,7 +86,7 @@
  .quad R_X86_64_64
 
 // CHECK:      Contents of section .R_X86_64_64:
-// CHECK-NEXT:   10158 58010100 00000000
+// CHECK-NEXT:   101ac ac010100 00000000
 
 .section .R_X86_64_GOTPCREL,"a",@progbits
 .global R_X86_64_GOTPCREL
@@ -96,4 +96,4 @@
 // 0x120A8 - 0x10160 = 8008
 // 8008 = 0x481f0000   in little endian
 // CHECK:      Contents of section .R_X86_64_GOTPCREL
-// CHECK-NEXT:   10160 481f0000
+// CHECK-NEXT:   101b4 f41e0000