diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h
--- a/lld/MachO/InputFiles.h
+++ b/lld/MachO/InputFiles.h
@@ -64,7 +64,6 @@
   MemoryBufferRef mb;
 
   std::vector<Symbol *> symbols;
-  ArrayRef<llvm::MachO::section_64> sectionHeaders;
   std::vector<SubsectionMap> subsections;
   // Provides an easy way to sort InputFiles deterministically.
   const int id;
@@ -80,15 +79,6 @@
   InputFile(Kind kind, const llvm::MachO::InterfaceFile &interface)
       : id(idCount++), fileKind(kind), name(saver.save(interface.getPath())) {}
 
-  void parseSections(ArrayRef<llvm::MachO::section_64>);
-
-  void parseSymbols(ArrayRef<lld::structs::nlist_64> nList, const char *strtab,
-                    bool subsectionsViaSymbols);
-
-  Symbol *parseNonSectionSymbol(const structs::nlist_64 &sym, StringRef name);
-
-  void parseRelocations(const llvm::MachO::section_64 &, SubsectionMap &);
-
 private:
   const Kind fileKind;
   const StringRef name;
@@ -99,21 +89,26 @@
 // .o file
 class ObjFile : public InputFile {
 public:
-  explicit ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName);
+  ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName);
   static bool classof(const InputFile *f) { return f->kind() == ObjKind; }
 
   llvm::DWARFUnit *compileUnit = nullptr;
   const uint32_t modTime;
+  ArrayRef<llvm::MachO::section_64> sectionHeaders;
 
 private:
+  void parseSections(ArrayRef<llvm::MachO::section_64>);
+  void parseSymbols(ArrayRef<lld::structs::nlist_64> nList, const char *strtab,
+                    bool subsectionsViaSymbols);
+  Symbol *parseNonSectionSymbol(const structs::nlist_64 &sym, StringRef name);
+  void parseRelocations(const llvm::MachO::section_64 &, SubsectionMap &);
   void parseDebugInfo();
 };
 
 // command-line -sectcreate file
 class OpaqueFile : public InputFile {
 public:
-  explicit OpaqueFile(MemoryBufferRef mb, StringRef segName,
-                      StringRef sectName);
+  OpaqueFile(MemoryBufferRef mb, StringRef segName, StringRef sectName);
   static bool classof(const InputFile *f) { return f->kind() == OpaqueKind; }
 };
 
diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -155,7 +155,7 @@
   return nullptr;
 }
 
-void InputFile::parseSections(ArrayRef<section_64> sections) {
+void ObjFile::parseSections(ArrayRef<section_64> sections) {
   subsections.reserve(sections.size());
   auto *buf = reinterpret_cast<const uint8_t *>(mb.getBufferStart());
 
@@ -192,8 +192,8 @@
   return it->second;
 }
 
-void InputFile::parseRelocations(const section_64 &sec,
-                                 SubsectionMap &subsecMap) {
+void ObjFile::parseRelocations(const section_64 &sec,
+                               SubsectionMap &subsecMap) {
   auto *buf = reinterpret_cast<const uint8_t *>(mb.getBufferStart());
   ArrayRef<any_relocation_info> anyRelInfos(
       reinterpret_cast<const any_relocation_info *>(buf + sec.reloff),
@@ -266,8 +266,8 @@
                        /*isExternal=*/false);
 }
 
-macho::Symbol *InputFile::parseNonSectionSymbol(const structs::nlist_64 &sym,
-                                                StringRef name) {
+macho::Symbol *ObjFile::parseNonSectionSymbol(const structs::nlist_64 &sym,
+                                              StringRef name) {
   uint8_t type = sym.n_type & N_TYPE;
   switch (type) {
   case N_UNDF:
@@ -289,8 +289,8 @@
   }
 }
 
-void InputFile::parseSymbols(ArrayRef<structs::nlist_64> nList,
-                             const char *strtab, bool subsectionsViaSymbols) {
+void ObjFile::parseSymbols(ArrayRef<structs::nlist_64> nList,
+                           const char *strtab, bool subsectionsViaSymbols) {
   // resize(), not reserve(), because we are going to create N_ALT_ENTRY symbols
   // out-of-sequence.
   symbols.resize(nList.size());
diff --git a/lld/MachO/InputSection.h b/lld/MachO/InputSection.h
--- a/lld/MachO/InputSection.h
+++ b/lld/MachO/InputSection.h
@@ -35,27 +35,11 @@
   llvm::PointerUnion<Symbol *, InputSection *> referent;
 };
 
-inline bool isZeroFill(uint32_t flags) {
-  return llvm::MachO::isVirtualSection(flags & llvm::MachO::SECTION_TYPE);
-}
-
-inline bool isThreadLocalVariables(uint32_t flags) {
-  return (flags & llvm::MachO::SECTION_TYPE) ==
-         llvm::MachO::S_THREAD_LOCAL_VARIABLES;
-}
-
-inline bool isDebugSection(uint32_t flags) {
-  return (flags & llvm::MachO::SECTION_ATTRIBUTES_USR) ==
-         llvm::MachO::S_ATTR_DEBUG;
-}
-
 class InputSection {
 public:
   virtual ~InputSection() = default;
   virtual uint64_t getSize() const { return data.size(); }
-  virtual uint64_t getFileSize() const {
-    return isZeroFill(flags) ? 0 : getSize();
-  }
+  virtual uint64_t getFileSize() const;
   uint64_t getFileOffset() const;
   uint64_t getVA() const;
 
@@ -76,6 +60,20 @@
   std::vector<Reloc> relocs;
 };
 
+inline bool isZeroFill(uint32_t flags) {
+  return llvm::MachO::isVirtualSection(flags & llvm::MachO::SECTION_TYPE);
+}
+
+inline bool isThreadLocalVariables(uint32_t flags) {
+  return (flags & llvm::MachO::SECTION_TYPE) ==
+         llvm::MachO::S_THREAD_LOCAL_VARIABLES;
+}
+
+inline bool isDebugSection(uint32_t flags) {
+  return (flags & llvm::MachO::SECTION_ATTRIBUTES_USR) ==
+         llvm::MachO::S_ATTR_DEBUG;
+}
+
 bool isCodeSection(InputSection *);
 
 extern std::vector<InputSection *> inputSections;
diff --git a/lld/MachO/InputSection.cpp b/lld/MachO/InputSection.cpp
--- a/lld/MachO/InputSection.cpp
+++ b/lld/MachO/InputSection.cpp
@@ -26,6 +26,10 @@
   return parent->fileOff + outSecFileOff;
 }
 
+uint64_t InputSection::getFileSize() const {
+  return isZeroFill(flags) ? 0 : getSize();
+}
+
 uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
 
 void InputSection::writeTo(uint8_t *buf) {