Index: ELF/InputSection.h
===================================================================
--- ELF/InputSection.h
+++ ELF/InputSection.h
@@ -12,6 +12,7 @@
 
 #include "Config.h"
 #include "lld/Core/LLVM.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Object/ELF.h"
 
@@ -143,10 +144,6 @@
   SplitInputSection(ObjectFile<ELFT> *File, const Elf_Shdr *Header,
                     typename InputSectionBase<ELFT>::Kind SectionKind);
 
-  // For each piece of data, we maintain the offsets in the input section and
-  // in the output section.
-  std::vector<std::pair<uintX_t, uintX_t>> Offsets;
-
   // Merge input sections may use the following special values as the output
   // section offset:
   enum {
@@ -161,6 +158,18 @@
 
   std::pair<std::pair<uintX_t, uintX_t> *, uintX_t>
   getRangeAndSize(uintX_t Offset);
+
+  std::vector<std::pair<uintX_t, uintX_t>> &getOffsets() {
+    ensureOffsets();
+    return Offsets;
+  }
+
+private:
+  void ensureOffsets();
+
+  // For each piece of data, we maintain the offsets in the input section and
+  // in the output section.
+  std::vector<std::pair<uintX_t, uintX_t>> Offsets;
 };
 
 // This corresponds to a SHF_MERGE section of an input file.
Index: ELF/InputSection.cpp
===================================================================
--- ELF/InputSection.cpp
+++ ELF/InputSection.cpp
@@ -413,11 +413,20 @@
 template <class ELFT>
 MergeInputSection<ELFT>::MergeInputSection(elf::ObjectFile<ELFT> *F,
                                            const Elf_Shdr *Header)
-    : SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::Merge) {
+    : SplitInputSection<ELFT>(F, Header, InputSectionBase<ELFT>::Merge) {}
+
+template <class ELFT>
+bool MergeInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
+  return S->SectionKind == InputSectionBase<ELFT>::Merge;
+}
+
+template <class ELFT> void SplitInputSection<ELFT>::ensureOffsets() {
+  if (this->SectionKind != InputSectionBase<ELFT>::Merge || !Offsets.empty())
+    return;
+
   uintX_t EntSize = Header->sh_entsize;
   ArrayRef<uint8_t> D = this->getSectionData();
   StringRef Data((const char *)D.data(), D.size());
-  std::vector<std::pair<uintX_t, uintX_t>> &Offsets = this->Offsets;
 
   uintX_t V = Config->GcSections ? MergeInputSection<ELFT>::PieceDead
                                  : MergeInputSection<ELFT>::PieceLive;
@@ -443,14 +452,10 @@
 }
 
 template <class ELFT>
-bool MergeInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
-  return S->SectionKind == InputSectionBase<ELFT>::Merge;
-}
-
-template <class ELFT>
 std::pair<std::pair<typename ELFT::uint, typename ELFT::uint> *,
           typename ELFT::uint>
 SplitInputSection<ELFT>::getRangeAndSize(uintX_t Offset) {
+  MutableArrayRef<std::pair<uintX_t, uintX_t>> Offsets = getOffsets();
   ArrayRef<uint8_t> D = this->getSectionData();
   StringRef Data((const char *)D.data(), D.size());
   uintX_t Size = Data.size();
Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -983,7 +983,7 @@
 
 template <class ELFT> StringRef EHRegion<ELFT>::data() const {
   ArrayRef<uint8_t> SecData = S->getSectionData();
-  ArrayRef<std::pair<uintX_t, uintX_t>> Offsets = S->Offsets;
+  ArrayRef<std::pair<uintX_t, uintX_t>> Offsets = S->getOffsets();
   size_t Start = Offsets[Index].first;
   size_t End =
       Index == Offsets.size() - 1 ? SecData.size() : Offsets[Index + 1].first;
@@ -1137,8 +1137,8 @@
 
   DenseMap<unsigned, unsigned> OffsetToIndex;
   while (!D.empty()) {
-    unsigned Index = S->Offsets.size();
-    S->Offsets.push_back(std::make_pair(Offset, -1));
+    unsigned Index = S->getOffsets().size();
+    S->getOffsets().push_back(std::make_pair(Offset, -1));
 
     uintX_t Length = readEntryLength<ELFT>(D);
     // If CIE/FDE data length is zero then Length is 4, this
@@ -1225,11 +1225,11 @@
 
   size_t Offset = 0;
   for (const Cie<ELFT> &C : Cies) {
-    C.S->Offsets[C.Index].second = Offset;
+    C.S->getOffsets()[C.Index].second = Offset;
     Offset += alignTo(C.data().size(), sizeof(uintX_t));
 
     for (const EHRegion<ELFT> &F : C.Fdes) {
-      F.S->Offsets[F.Index].second = Offset;
+      F.S->getOffsets()[F.Index].second = Offset;
       Offset += alignTo(F.data().size(), sizeof(uintX_t));
     }
   }
@@ -1238,11 +1238,11 @@
 template <class ELFT> void EHOutputSection<ELFT>::writeTo(uint8_t *Buf) {
   const endianness E = ELFT::TargetEndianness;
   for (const Cie<ELFT> &C : Cies) {
-    size_t CieOffset = C.S->Offsets[C.Index].second;
+    size_t CieOffset = C.S->getOffsets()[C.Index].second;
     writeAlignedCieOrFde<ELFT>(C.data(), Buf + CieOffset);
 
     for (const EHRegion<ELFT> &F : C.Fdes) {
-      size_t Offset = F.S->Offsets[F.Index].second;
+      size_t Offset = F.S->getOffsets()[F.Index].second;
       writeAlignedCieOrFde<ELFT>(F.data(), Buf + Offset);
       write32<E>(Buf + Offset + 4, Offset + 4 - CieOffset); // Pointer
 
@@ -1282,7 +1282,7 @@
   StringRef Data((const char *)D.data(), D.size());
   uintX_t EntSize = S->getSectionHdr()->sh_entsize;
   this->Header.sh_entsize = EntSize;
-  MutableArrayRef<std::pair<uintX_t, uintX_t>> Offsets = S->Offsets;
+  MutableArrayRef<std::pair<uintX_t, uintX_t>> Offsets = S->getOffsets();
 
   // If this is of type string, the contents are null-terminated strings.
   if (this->Header.sh_flags & SHF_STRINGS) {