diff --git a/llvm/lib/MC/MCSection.cpp b/llvm/lib/MC/MCSection.cpp
index 65e86d3..291e40d 100644
--- a/llvm/lib/MC/MCSection.cpp
+++ b/llvm/lib/MC/MCSection.cpp
@@ -115,25 +115,272 @@
 // MCSectionMachO
 //===----------------------------------------------------------------------===//
 
-MCSectionMachO *MCSectionMachO::
-Create(const StringRef &Name, bool IsDirective, SectionKind K, MCContext &Ctx) {
-  return new (Ctx) MCSectionMachO(Name, IsDirective, K, Ctx);
-}
+/// SectionTypeDescriptors - These are strings that describe the various section
+/// types.  This *must* be kept in order with and stay synchronized with the
+/// section type list.
+static const struct {
+  const char *AssemblerName, *EnumName;
+} SectionTypeDescriptors[MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1] = {
+  { "regular",                  "S_REGULAR" },                    // 0x00
+  { 0,                          "S_ZEROFILL" },                   // 0x01
+  { "cstring_literals",         "S_CSTRING_LITERALS" },           // 0x02
+  { "4byte_literals",           "S_4BYTE_LITERALS" },             // 0x03
+  { "8byte_literals",           "S_8BYTE_LITERALS" },             // 0x04
+  { "literal_pointers",         "S_LITERAL_POINTERS" },           // 0x05
+  { "non_lazy_symbol_pointers", "S_NON_LAZY_SYMBOL_POINTERS" },   // 0x06
+  { "lazy_symbol_pointers",     "S_LAZY_SYMBOL_POINTERS" },       // 0x07
+  { "symbol_stubs",             "S_SYMBOL_STUBS" },               // 0x08
+  { "mod_init_funcs",           "S_MOD_INIT_FUNC_POINTERS" },     // 0x09
+  { "mod_term_funcs",           "S_MOD_TERM_FUNC_POINTERS" },     // 0x0A
+  { "coalesced",                "S_COALESCED" },                  // 0x0B
+  { 0, /*FIXME??*/              "S_GB_ZEROFILL" },                // 0x0C
+  { "interposing",              "S_INTERPOSING" },                // 0x0D
+  { "16byte_literals",          "S_16BYTE_LITERALS" },            // 0x0E
+  { 0, /*FIXME??*/              "S_DTRACE_DOF" },                 // 0x0F
+  { 0, /*FIXME??*/              "S_LAZY_DYLIB_SYMBOL_POINTERS" }  // 0x10
+};
 
-MCSectionMachO::MCSectionMachO(const StringRef &name, bool isDirective,
-                               SectionKind K, MCContext &Ctx)
-  : MCSection(K), Name(name), IsDirective(isDirective) {
-  Ctx.SetSection(Name, this);
+
+/// SectionAttrDescriptors - This is an array of descriptors for section
+/// attributes.  Unlike the SectionTypeDescriptors, this is not directly indexed
+/// by attribute, instead it is searched.  The last entry has a zero AttrFlag
+/// value.
+static const struct {
+  unsigned AttrFlag;
+  const char *AssemblerName, *EnumName;
+} SectionAttrDescriptors[] = {
+#define ENTRY(ASMNAME, ENUM) \
+  { MCSectionMachO::ENUM, ASMNAME, #ENUM },
+ENTRY("pure_instructions",   S_ATTR_PURE_INSTRUCTIONS)
+ENTRY("no_toc",              S_ATTR_NO_TOC)
+ENTRY("strip_static_syms",   S_ATTR_STRIP_STATIC_SYMS)
+ENTRY("no_dead_strip",       S_ATTR_NO_DEAD_STRIP)
+ENTRY("live_support",        S_ATTR_LIVE_SUPPORT)
+ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
+ENTRY("debug",               S_ATTR_DEBUG)
+ENTRY(0 /*FIXME*/,           S_ATTR_SOME_INSTRUCTIONS)
+ENTRY(0 /*FIXME*/,           S_ATTR_EXT_RELOC)
+ENTRY(0 /*FIXME*/,           S_ATTR_LOC_RELOC)
+#undef ENTRY
+  { 0, "none", 0 }
+};
+
+
+MCSectionMachO *MCSectionMachO::
+Create(const StringRef &Segment, const StringRef &Section,
+       unsigned TypeAndAttributes, unsigned Reserved2,
+       SectionKind K, MCContext &Ctx) {
+  // S_SYMBOL_STUBS must be set for Reserved2 to be non-zero.
+  return new (Ctx) MCSectionMachO(Segment, Section, TypeAndAttributes,
+                                  Reserved2, K);
 }
 
 void MCSectionMachO::PrintSwitchToSection(const TargetAsmInfo &TAI,
                                           raw_ostream &OS) const {
-  if (!isDirective())
-    OS << "\t.section\t" << getName() << '\n';
+  OS << "\t.section\t" << getSegmentName() << ',' << getSectionName();
+  
+  // Get the section type and attributes.
+  unsigned TAA = getTypeAndAttributes();
+  if (TAA == 0) {
+    OS << '\n';
+    return;
+  }
+
+  OS << ',';
+  
+  unsigned SectionType = TAA & MCSectionMachO::SECTION_TYPE;
+  assert(SectionType <= MCSectionMachO::LAST_KNOWN_SECTION_TYPE &&
+         "Invalid SectionType specified!");
+
+  if (SectionTypeDescriptors[SectionType].AssemblerName)
+    OS << SectionTypeDescriptors[SectionType].AssemblerName;
   else
-    OS << getName() << '\n';
+    OS << "<<" << SectionTypeDescriptors[SectionType].EnumName << ">>";
+  
+  // If we don't have any attributes, we're done.
+  unsigned SectionAttrs = TAA & MCSectionMachO::SECTION_ATTRIBUTES;
+  if (SectionAttrs == 0) {
+    // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
+    // the attribute specifier.
+    if (Reserved2 != 0)
+      OS << ",none," << Reserved2;
+    OS << '\n';
+    return;
+  }
+
+  // Check each attribute to see if we have it.
+  char Separator = ',';
+  for (unsigned i = 0; SectionAttrDescriptors[i].AttrFlag; ++i) {
+    // Check to see if we have this attribute.
+    if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0)
+      continue;
+    
+    // Yep, clear it and print it.
+    SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag;
+    
+    OS << Separator;
+    if (SectionAttrDescriptors[i].AssemblerName)
+      OS << SectionAttrDescriptors[i].AssemblerName;
+    else
+      OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>";
+    Separator = '+';
+  }
+  
+  assert(SectionAttrs == 0 && "Unknown section attributes!");
+  
+  // If we have a S_SYMBOL_STUBS size specified, print it.
+  if (Reserved2 != 0)
+    OS << ',' << Reserved2;
+  OS << '\n';
 }
 
+/// StripSpaces - This removes leading and trailing spaces from the StringRef.
+static void StripSpaces(StringRef &Str) {
+  while (!Str.empty() && isspace(Str[0]))
+    Str = Str.substr(1);
+  while (!Str.empty() && isspace(Str.back()))
+    Str = Str.substr(0, Str.size()-1);
+}
+
+/// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
+/// This is a string that can appear after a .section directive in a mach-o
+/// flavored .s file.  If successful, this fills in the specified Out
+/// parameters and returns an empty string.  When an invalid section
+/// specifier is present, this returns a string indicating the problem.
+std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
+                                                  StringRef &Segment,    // Out.
+                                                  StringRef &Section,    // Out.
+                                                  unsigned  &TAA,        // Out.
+                                                  unsigned  &StubSize) { // Out.
+  // Find the first comma.
+  std::pair<StringRef, StringRef> Comma = Spec.split(',');
+  
+  // If there is no comma, we fail.
+  if (Comma.second.empty())
+    return "mach-o section specifier requires a segment and section "
+           "separated by a comma";
+  
+  // Capture segment, remove leading and trailing whitespace.
+  Segment = Comma.first;
+  StripSpaces(Segment);
+
+  // Verify that the segment is present and not too long.
+  if (Segment.empty() || Segment.size() > 16)
+    return "mach-o section specifier requires a segment whose length is "
+           "between 1 and 16 characters";
+  
+  // Split the section name off from any attributes if present.
+  Comma = Comma.second.split(',');
+
+  // Capture section, remove leading and trailing whitespace.
+  Section = Comma.first;
+  StripSpaces(Section);
+  
+  // Verify that the section is present and not too long.
+  if (Section.empty() || Section.size() > 16)
+    return "mach-o section specifier requires a section whose length is "
+           "between 1 and 16 characters";
+
+  // If there is no comma after the section, we're done.
+  TAA = 0;
+  StubSize = 0;
+  if (Comma.second.empty())
+    return "";
+  
+  // Otherwise, we need to parse the section type and attributes.
+  Comma = Comma.second.split(',');
+  
+  // Get the section type.
+  StringRef SectionType = Comma.first;
+  StripSpaces(SectionType);
+  
+  // Figure out which section type it is.
+  unsigned TypeID;
+  for (TypeID = 0; TypeID !=MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1; ++TypeID)
+    if (SectionTypeDescriptors[TypeID].AssemblerName &&
+        SectionType == SectionTypeDescriptors[TypeID].AssemblerName)
+      break;
+  
+  // If we didn't find the section type, reject it.
+  if (TypeID > MCSectionMachO::LAST_KNOWN_SECTION_TYPE)
+    return "mach-o section specifier uses an unknown section type";
+  
+  // Remember the TypeID.
+  TAA = TypeID;
+
+  // If we have no comma after the section type, there are no attributes.
+  if (Comma.second.empty()) {
+    // S_SYMBOL_STUBS always require a symbol stub size specifier.
+    if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
+      return "mach-o section specifier of type 'symbol_stubs' requires a size "
+             "specifier";
+    return "";
+  }
+
+  // Otherwise, we do have some attributes.  Split off the size specifier if
+  // present.
+  Comma = Comma.second.split(',');
+  StringRef Attrs = Comma.first;
+  
+  // The attribute list is a '+' separated list of attributes.
+  std::pair<StringRef, StringRef> Plus = Attrs.split('+');
+  
+  while (1) {
+    StringRef Attr = Plus.first;
+    StripSpaces(Attr);
+
+    // Look up the attribute.
+    for (unsigned i = 0; ; ++i) {
+      if (SectionAttrDescriptors[i].AttrFlag == 0)
+        return "mach-o section specifier has invalid attribute";
+      
+      if (SectionAttrDescriptors[i].AssemblerName &&
+          Attr == SectionAttrDescriptors[i].AssemblerName) {
+        TAA |= SectionAttrDescriptors[i].AttrFlag;
+        break;
+      }
+    }
+    
+    if (Plus.second.empty()) break;
+    Plus = Plus.second.split('+');
+  };
+
+  // Okay, we've parsed the section attributes, see if we have a stub size spec.
+  if (Comma.second.empty()) {
+    // S_SYMBOL_STUBS always require a symbol stub size specifier.
+    if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
+      return "mach-o section specifier of type 'symbol_stubs' requires a size "
+      "specifier";
+    return "";
+  }
+
+  // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
+  if ((TAA & MCSectionMachO::SECTION_TYPE) != MCSectionMachO::S_SYMBOL_STUBS)
+    return "mach-o section specifier cannot have a stub size specified because "
+           "it does not have type 'symbol_stubs'";
+  
+  // Okay, if we do, it must be a number.
+  StringRef StubSizeStr = Comma.second;
+  StripSpaces(StubSizeStr);
+  
+  // Convert the a null terminated buffer for strtoul.
+  char TmpBuffer[32];
+  if (StubSizeStr.size() >= 32)
+    return"mach-o section specifier has a stub size specifier that is too long";
+  
+  memcpy(TmpBuffer, StubSizeStr.data(), StubSizeStr.size());
+  TmpBuffer[StubSizeStr.size()] = 0;
+  
+  char *EndPtr;
+  StubSize = strtoul(TmpBuffer, &EndPtr, 0);
+
+  if (EndPtr[0] != 0)
+    return "mach-o section specifier has a malformed stub size";
+  
+  return "";
+}
+
+
 //===----------------------------------------------------------------------===//
 // MCSectionCOFF
 //===----------------------------------------------------------------------===//