diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index 7b26d549377..f6279768ca2 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -84,6 +84,11 @@ namespace llvm {
     MCDwarfLoc CurrentDwarfLoc;
     bool DwarfLocSeen;
 
+    /// Honor temporary labels, this is useful for debugging semantic
+    /// differences between temporary and non-temporary labels (primarily on
+    /// Darwin).
+    bool AllowTemporaryLabels;
+
     /// The dwarf line information from the .loc directives for the sections
     /// with assembled machine instructions have after seeing .loc directives.
     DenseMap<const MCSection *, MCLineSection *> MCLineSections;
@@ -109,6 +114,8 @@ namespace llvm {
 
     const TargetAsmInfo &getTargetAsmInfo() const { return *TAI; }
 
+    void setAllowTemporaryLabels(bool Value) { AllowTemporaryLabels = Value; }
+
     /// @name Symbol Management
     /// @{
 
diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index 018f00c08f6..7c687135fc6 100644
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -28,7 +28,8 @@ typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
 
 MCContext::MCContext(const MCAsmInfo &mai, const TargetAsmInfo *tai) :
   MAI(mai), TAI(tai), NextUniqueID(0),
-  CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0) {
+  CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
+  AllowTemporaryLabels(true) {
   MachOUniquingMap = 0;
   ELFUniquingMap = 0;
   COFFUniquingMap = 0;
@@ -76,8 +77,10 @@ MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
 }
 
 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
-  // Determine whether this is an assembler temporary or normal label.
-  bool isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
+  // Determine whether this is an assembler temporary or normal label, if used.
+  bool isTemporary = false;
+  if (AllowTemporaryLabels)
+    isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
 
   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
   if (NameEntry->getValue()) {
diff --git a/test/MC/MachO/temp-labels.s b/test/MC/MachO/temp-labels.s
new file mode 100644
index 00000000000..b7382b7d2c8
--- /dev/null
+++ b/test/MC/MachO/temp-labels.s
@@ -0,0 +1,33 @@
+// RUN: llvm-mc -triple x86_64-apple-darwin10 %s -filetype=obj -L -o - | macho-dump --dump-section-data | FileCheck %s
+
+// CHECK:   # Load Command 1
+// CHECK:  (('command', 2)
+// CHECK:   ('size', 24)
+// CHECK:   ('symoff', 296)
+// CHECK:   ('nsyms', 2)
+// CHECK:   ('stroff', 328)
+// CHECK:   ('strsize', 8)
+// CHECK:   ('_string_data', '\x00_f0\x00L0\x00')
+// CHECK:   ('_symbols', [
+// CHECK:     # Symbol 0
+// CHECK:    (('n_strx', 1)
+// CHECK:     ('n_type', 0xe)
+// CHECK:     ('n_sect', 1)
+// CHECK:     ('n_desc', 0)
+// CHECK:     ('n_value', 0)
+// CHECK:     ('_string', '_f0')
+// CHECK:    ),
+// CHECK:     # Symbol 1
+// CHECK:    (('n_strx', 5)
+// CHECK:     ('n_type', 0xe)
+// CHECK:     ('n_sect', 1)
+// CHECK:     ('n_desc', 0)
+// CHECK:     ('n_value', 4)
+// CHECK:     ('_string', 'L0')
+// CHECK:    ),
+// CHECK:   ])
+// CHECK:  ),
+_f0:
+        .long 0
+L0:
+        .long 0
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index b7818665abf..f76b6edb80e 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -113,6 +113,10 @@ static cl::opt<bool>
 NoInitialTextSection("n", cl::desc(
                    "Don't assume assembly file starts in the text section"));
 
+static cl::opt<bool>
+SaveTempLabels("L", cl::desc(
+                 "Don't discard temporary labels"));
+
 enum ActionType {
   AC_AsLex,
   AC_Assemble,
@@ -327,6 +331,8 @@ static int AssembleInput(const char *ProgName) {
 
   const TargetAsmInfo *tai = new TargetAsmInfo(*TM);
   MCContext Ctx(*MAI, tai);
+  if (SaveTempLabels)
+    Ctx.setAllowTemporaryLabels(false);
 
   OwningPtr<tool_output_file> Out(GetOutputStream());
   if (!Out)