Index: ELF/SyntheticSections.h
===================================================================
--- ELF/SyntheticSections.h
+++ ELF/SyntheticSections.h
@@ -784,9 +784,13 @@
 
 class ARMExidxSentinelSection : public SyntheticSection {
 public:
+  static ARMExidxSentinelSection *create();
+
   ARMExidxSentinelSection();
   size_t getSize() const override { return 8; }
   void writeTo(uint8_t *Buf) override;
+
+  InputSection *Highest = 0;
 };
 
 // A container for one or more linker generated thunks. Instances of these
Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -2556,6 +2556,20 @@
     : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, Config->Wordsize,
                        ".rld_map") {}
 
+ARMExidxSentinelSection *ARMExidxSentinelSection::create() {
+  if (Config->Relocatable)
+    return nullptr;
+
+  // Find if there are live ARM exidx input sections.
+  if (InputSections.end() ==
+      llvm::find_if(InputSections, [](InputSectionBase *Sec) {
+        return Sec->Type == SHT_ARM_EXIDX && Sec->Live;
+      }))
+    return nullptr;
+
+  return make<ARMExidxSentinelSection>();
+}
+
 ARMExidxSentinelSection::ARMExidxSentinelSection()
     : SyntheticSection(SHF_ALLOC | SHF_LINK_ORDER, SHT_ARM_EXIDX,
                        Config->Wordsize, ".ARM.exidx") {}
@@ -2567,23 +2581,6 @@
 // The sentinel must have the PREL31 value of an address higher than any
 // address described by any other table entry.
 void ARMExidxSentinelSection::writeTo(uint8_t *Buf) {
-  // The Sections are sorted in order of ascending PREL31 address with the
-  // sentinel last. We need to find the InputSection that precedes the
-  // sentinel.
-  OutputSection *C = getParent();
-  InputSection *Highest = nullptr;
-  unsigned Skip = 1;
-  for (const BaseCommand *Base : llvm::reverse(C->SectionCommands)) {
-    if (!isa<InputSectionDescription>(Base))
-      continue;
-    auto L = cast<InputSectionDescription>(Base);
-    if (Skip >= L->Sections.size()) {
-      Skip -= L->Sections.size();
-      continue;
-    }
-    Highest = L->Sections[L->Sections.size() - Skip - 1];
-    break;
-  }
   assert(Highest);
   InputSection *LS = Highest->getLinkOrderDep();
   uint64_t S = LS->getParent()->Addr + LS->getOffset(LS->getSize());
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -54,7 +54,6 @@
   void resolveShfLinkOrder();
   void sortInputSections();
   void finalizeSections();
-  void addPredefinedSections();
   void setReservedSymbolSections();
 
   std::vector<PhdrEntry *> createPhdrs();
@@ -390,6 +389,12 @@
   Add(InX::ShStrTab);
   if (InX::StrTab)
     Add(InX::StrTab);
+
+  if (Config->EMachine == EM_ARM)
+    // Add a sentinel to terminate .ARM.exidx. It helps an unwinder
+    // to find the exact address range of the last entry.
+    if (auto *Sec = ARMExidxSentinelSection::create())
+      Add(Sec);
 }
 
 // The main function of the writer.
@@ -1145,10 +1150,10 @@
 }
 
 static bool compareByFilePosition(InputSection *A, InputSection *B) {
-  // Synthetic doesn't have link order dependecy, stable_sort will keep it last
+  // Synthetic, i. e. a sentinel section, should go last.
   if (A->kind() == InputSectionBase::Synthetic ||
       B->kind() == InputSectionBase::Synthetic)
-    return false;
+    return A->kind() != InputSectionBase::Synthetic;
   InputSection *LA = A->getLinkOrderDep();
   InputSection *LB = B->getLinkOrderDep();
   OutputSection *AOut = LA->getParent();
@@ -1175,9 +1180,21 @@
         }
       }
     }
+    if (Sections.empty())
+      continue;
+
     std::stable_sort(Sections.begin(), Sections.end(), compareByFilePosition);
     for (int I = 0, N = Sections.size(); I < N; ++I)
       *ScriptSections[I] = Sections[I];
+
+    // The last actual entry is required to fill the sentinel.
+    // Remember it here so that we don't have to find it again.
+    if (auto *Sentinel = dyn_cast<ARMExidxSentinelSection>(Sections.back())) {
+      assert(Sections.size() >= 2 &&
+             "We should create a sentinel section only if there are "
+             "alive regular exidx sections.");
+      Sentinel->Highest = Sections[Sections.size() - 2];
+    }
   }
 }
 
@@ -1331,7 +1348,6 @@
   if (errorCount())
     return;
 
-  addPredefinedSections();
   removeUnusedSyntheticSections();
 
   sortSections();
@@ -1427,17 +1443,6 @@
                  [](SyntheticSection *SS) { SS->postThunkContents(); });
 }
 
-template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
-  // ARM ABI requires .ARM.exidx to be terminated by some piece of data.
-  // We have the terminater synthetic section class. Add that at the end.
-  OutputSection *Cmd = findSection(".ARM.exidx");
-  if (!Cmd || !Cmd->Live || Config->Relocatable)
-    return;
-
-  auto *Sentinel = make<ARMExidxSentinelSection>();
-  Cmd->addSection(Sentinel);
-}
-
 // The linker is expected to define SECNAME_start and SECNAME_end
 // symbols for a few sections. This function defines them.
 template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {
Index: test/ELF/linkerscript/arm-exidx-sentinel-and-assignment.s
===================================================================
--- test/ELF/linkerscript/arm-exidx-sentinel-and-assignment.s
+++ test/ELF/linkerscript/arm-exidx-sentinel-and-assignment.s
@@ -7,7 +7,8 @@
 ## We used to crash if the last output section command for .ARM.exidx
 ## was anything but an input section description.
 # RUN: ld.lld -T %t.script %t.o -shared -o %t.so
-# RUN: llvm-objdump -s -triple=armv7a-none-linux-gnueabi %t.so | FileCheck %s
+# RUN: llvm-objdump -s -triple=armv7a-none-linux-gnueabi %t.so | FileCheck %s --check-prefix=DUMP
+# RUN: llvm-readobj -s -t %t.so | FileCheck %s
 
  .syntax unified
  .text
@@ -18,7 +19,23 @@
  bx lr
  .fnend
 
-// CHECK: Contents of section .ARM.exidx:
-// 1000 + 1000 = 0x2000 = _start
-// 1008 + 0ffc = 0x2004 = _start + sizeof(_start)
-// CHECK-NEXT: 1000 00100000 01000000 fc0f0000 01000000
+# DUMP: Contents of section .ARM.exidx:
+# 1000 + 1000 = 0x2000 = _start
+# 1008 + 0ffc = 0x2004 = _start + sizeof(_start)
+# DUMP-NEXT: 1000 00100000 01000000 fc0f0000 01000000
+
+# CHECK:       Section {
+# CHECK:         Name: .ARM.exidx
+# CHECK-NEXT:    Type: SHT_ARM_EXIDX
+# CHECK-NEXT:    Flags [
+# CHECK-NEXT:      SHF_ALLOC
+# CHECK-NEXT:      SHF_LINK_ORDER
+# CHECK-NEXT:    ]
+# CHECK-NEXT:    Address: 0x1000
+# CHECK-NEXT:    Offset:
+# CHECK-NEXT:    Size: 16
+
+# Symbol 'foo' is expected to point at the end of the section.
+# CHECK:       Symbol {
+# CHECK:         Name: foo
+# CHECK-NEXT:    Value: 0x1010