diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
index aa7a445de09..61d9c865e18 100644
--- a/include/llvm/MC/MCAssembler.h
+++ b/include/llvm/MC/MCAssembler.h
@@ -12,7 +12,6 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/ilist.h"
@@ -574,7 +573,7 @@ class MCAssembler {
   friend class MCAsmLayout;
 
 public:
-  typedef SetVector<MCSection *> SectionListType;
+  typedef std::vector<MCSection *> SectionListType;
   typedef std::vector<const MCSymbol *> SymbolDataListType;
 
   typedef pointee_iterator<SectionListType::const_iterator> const_iterator;
@@ -903,7 +902,13 @@ public:
   /// \name Backend Data Access
   /// @{
 
-  bool registerSection(MCSection &Section) { return Sections.insert(&Section); }
+  bool registerSection(MCSection &Section) {
+    if (Section.isRegistered())
+      return false;
+    Sections.push_back(&Section);
+    Section.setIsRegistered(true);
+    return true;
+  }
 
   bool hasSymbolData(const MCSymbol &Symbol) const { return Symbol.hasData(); }
 
diff --git a/include/llvm/MC/MCSection.h b/include/llvm/MC/MCSection.h
index ceb86cdc9aa..5f6e8ec1d50 100644
--- a/include/llvm/MC/MCSection.h
+++ b/include/llvm/MC/MCSection.h
@@ -78,6 +78,8 @@ private:
   /// Whether this section has had instructions emitted into it.
   unsigned HasInstructions : 1;
 
+  unsigned IsRegistered : 1;
+
   FragmentListType Fragments;
 
   /// Mapping from subsection number to insertion point for subsection numbers
@@ -130,6 +132,9 @@ public:
   bool hasInstructions() const { return HasInstructions; }
   void setHasInstructions(bool Value) { HasInstructions = Value; }
 
+  bool isRegistered() const { return IsRegistered; }
+  void setIsRegistered(bool Value) { IsRegistered = Value; }
+
   MCSection::FragmentListType &getFragmentList() { return Fragments; }
   const MCSection::FragmentListType &getFragmentList() const {
     return const_cast<MCSection *>(this)->getFragmentList();
diff --git a/lib/MC/MCSection.cpp b/lib/MC/MCSection.cpp
index d39cb5db731..9152f2b42a4 100644
--- a/lib/MC/MCSection.cpp
+++ b/lib/MC/MCSection.cpp
@@ -21,7 +21,7 @@ using namespace llvm;
 
 MCSection::MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin)
     : Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
-      Variant(V), Kind(K) {}
+      IsRegistered(false), Variant(V), Kind(K) {}
 
 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
   if (!End)
diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index 94c26cc0964..1ee3244684a 100644
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -789,9 +789,7 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
   uint64_t SectionDataSize = 0;
   uint64_t SectionDataFileSize = 0;
   uint64_t VMSize = 0;
-  for (MCAssembler::const_iterator it = Asm.begin(),
-         ie = Asm.end(); it != ie; ++it) {
-    const MCSection &Sec = *it;
+  for (const MCSection &Sec : Asm) {
     uint64_t Address = getSectionAddress(&Sec);
     uint64_t Size = Layout.getSectionAddressSize(&Sec);
     uint64_t FileSize = Layout.getSectionFileSize(&Sec);
@@ -799,7 +797,7 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
 
     VMSize = std::max(VMSize, Address + Size);
 
-    if (it->isVirtualSection())
+    if (Sec.isVirtualSection())
       continue;
 
     SectionDataSize = std::max(SectionDataSize, Address + Size);
@@ -820,12 +818,11 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
 
   // ... and then the section headers.
   uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
-  for (MCAssembler::const_iterator it = Asm.begin(),
-         ie = Asm.end(); it != ie; ++it) {
-    std::vector<RelAndSymbol> &Relocs = Relocations[&*it];
+  for (const MCSection &Sec : Asm) {
+    std::vector<RelAndSymbol> &Relocs = Relocations[&Sec];
     unsigned NumRelocs = Relocs.size();
-    uint64_t SectionStart = SectionDataStart + getSectionAddress(&*it);
-    WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
+    uint64_t SectionStart = SectionDataStart + getSectionAddress(&Sec);
+    WriteSection(Asm, Layout, Sec, SectionStart, RelocTableEnd, NumRelocs);
     RelocTableEnd += NumRelocs * sizeof(MachO::any_relocation_info);
   }
 
@@ -899,9 +896,7 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
   }
 
   // Write the actual section data.
-  for (MCAssembler::const_iterator it = Asm.begin(),
-         ie = Asm.end(); it != ie; ++it) {
-    MCSection &Sec = *it;
+  for (const MCSection &Sec : Asm) {
     Asm.writeSectionData(&Sec, Layout);
 
     uint64_t Pad = getPaddingSize(&Sec, Layout);
@@ -912,11 +907,10 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
   WriteZeros(SectionDataPadding);
 
   // Write the relocation entries.
-  for (MCAssembler::const_iterator it = Asm.begin(),
-         ie = Asm.end(); it != ie; ++it) {
+  for (const MCSection &Sec : Asm) {
     // Write the section relocation entries, in reverse order to match 'as'
     // (approximately, the exact algorithm is more complicated than this).
-    std::vector<RelAndSymbol> &Relocs = Relocations[&*it];
+    std::vector<RelAndSymbol> &Relocs = Relocations[&Sec];
     for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
       Write32(Relocs[e - i - 1].MRE.r_word0);
       Write32(Relocs[e - i - 1].MRE.r_word1);
diff --git a/lib/MC/WinCOFFObjectWriter.cpp b/lib/MC/WinCOFFObjectWriter.cpp
index 2f6d1805605..0290880bde7 100644
--- a/lib/MC/WinCOFFObjectWriter.cpp
+++ b/lib/MC/WinCOFFObjectWriter.cpp
@@ -1021,7 +1021,7 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
 
   {
     sections::iterator i, ie;
-    MCAssembler::const_iterator j, je;
+    MCAssembler::iterator j, je;
 
     for (auto &Section : Sections) {
       if (Section->Number != -1) {