Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -240,6 +240,8 @@
   Loc = Buf;
   if (uint32_t Filler = Script<ELFT>::X->getFiller(this->Name))
     fill(Buf, this->Size, Filler);
+  else if (Flags & SHF_EXECINSTR)
+    fill(Buf, this->Size, Target->DefaultExecutableFill);
 
   auto Fn = [=](InputSection *IS) { IS->writeTo<ELFT>(Buf); };
   forEach(Sections.begin(), Sections.end(), Fn);
Index: ELF/Target.h
===================================================================
--- ELF/Target.h
+++ ELF/Target.h
@@ -98,6 +98,8 @@
   virtual void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
   virtual void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
   virtual void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
+
+  uint32_t DefaultExecutableFill = 0;
 };
 
 uint64_t getPPC64TocBase();
Index: ELF/Target.cpp
===================================================================
--- ELF/Target.cpp
+++ ELF/Target.cpp
@@ -355,6 +355,8 @@
   PltEntrySize = 16;
   PltHeaderSize = 16;
   TlsGdRelaxSkip = 2;
+  // 0xCC is the "int3" (call debug exception handler) instruction.
+  DefaultExecutableFill = 0xcccccccc;
 }
 
 RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
@@ -647,6 +649,8 @@
   // Align to the large page size (known as a superpage or huge page).
   // FreeBSD automatically promotes large, superpage-aligned allocations.
   DefaultImageBase = 0x200000;
+  // 0xCC is the "int3" (call debug exception handler) instruction.
+  DefaultExecutableFill = 0xcccccccc;
 }
 
 template <class ELFT>
Index: test/ELF/default-fill.s
===================================================================
--- test/ELF/default-fill.s
+++ test/ELF/default-fill.s
@@ -0,0 +1,22 @@
+# REQUIRES: x86
+# Verify that the fill between sections has a default of interrupt instructions
+# (0xcc on x86)
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t.elf
+# RUN: llvm-objdump -disassemble %t.elf | FileCheck %s
+# CHECK-NOT: 00 00 addb
+# CHECK: cc int3
+# CHECK-NOT: 00 00 addb
+
+.section .text.1,"ax",@progbits
+.align 16
+.globl _start
+_start:
+  retq
+
+.section .text.2,"ax",@progbits
+.align 16
+.globl other
+other:
+  retq
Index: test/ELF/linkerscript/excludefile.s
===================================================================
--- test/ELF/linkerscript/excludefile.s
+++ test/ELF/linkerscript/excludefile.s
@@ -13,11 +13,13 @@
 # CHECK: _start:
 # CHECK-NEXT: :       48 c7 c0 3c 00 00 00    movq    $60, %rax
 # CHECK-NEXT: :       48 c7 c7 2a 00 00 00    movq    $42, %rdi
-# CHECK-NEXT: :       00 00   addb    %al, (%rax)
+# CHECK-NEXT: :       cc      int3
+# CHECK-NEXT: :       cc      int3
 # CHECK: _potato:
 # CHECK-NEXT: :       90      nop
 # CHECK-NEXT: :       90      nop
-# CHECK-NEXT: :       00 00   addb    %al, (%rax)
+# CHECK-NEXT: :       cc      int3
+# CHECK-NEXT: :       cc      int3
 # CHECK: tomato:
 # CHECK-NEXT: :       b8 01 00 00 00  movl    $1, %eax
 
@@ -31,7 +33,8 @@
 # EXCLUDE: _start:
 # EXCLUDE-NEXT: :       48 c7 c0 3c 00 00 00    movq    $60, %rax
 # EXCLUDE-NEXT: :       48 c7 c7 2a 00 00 00    movq    $42, %rdi
-# EXCLUDE-NEXT: :       00 00   addb    %al, (%rax)
+# EXCLUDE-NEXT: :       cc      int3
+# EXCLUDE-NEXT: :       cc      int3
 # EXCLUDE: _potato:
 # EXCLUDE-NEXT: :       90      nop
 # EXCLUDE-NEXT: :       90      nop