Index: llvm/trunk/include/llvm/MC/MCStreamer.h
===================================================================
--- llvm/trunk/include/llvm/MC/MCStreamer.h
+++ llvm/trunk/include/llvm/MC/MCStreamer.h
@@ -131,6 +131,10 @@
 
   void finish() override;
 
+  /// Reset any state between object emissions, i.e. the equivalent of
+  /// MCStreamer's reset method.
+  virtual void reset();
+
   /// Callback used to implement the ldr= pseudo.
   /// Add a new entry to the constant pool for the current section and return an
   /// MCExpr that can be used to refer to the constant pool location.
Index: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -388,6 +388,9 @@
 
   size_t calculateContentSize() const;
 
+  // Reset state between object emissions
+  void reset() override;
+
 public:
   ARMTargetELFStreamer(MCStreamer &S)
     : ARMTargetStreamer(S), CurrentVendor("aeabi"), FPU(ARM::FK_INVALID),
@@ -415,7 +418,7 @@
                  MCCodeEmitter *Emitter, bool IsThumb)
       : MCELFStreamer(Context, TAB, OS, Emitter), IsThumb(IsThumb),
         MappingSymbolCounter(0), LastEMS(EMS_None) {
-    Reset();
+    EHReset();
   }
 
   ~ARMELFStreamer() {}
@@ -579,7 +582,10 @@
   }
 
   // Helper functions for ARM exception handling directives
-  void Reset();
+  void EHReset();
+
+  // Reset state between object emissions
+  void reset() override;
 
   void EmitPersonalityFixup(StringRef Name);
   void FlushPendingOffset();
@@ -1040,6 +1046,8 @@
   getStreamer().emitInst(Inst, Suffix);
 }
 
+void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
+
 void ARMELFStreamer::FinishImpl() {
   MCTargetStreamer &TS = *getTargetStreamer();
   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
@@ -1048,6 +1056,18 @@
   MCELFStreamer::FinishImpl();
 }
 
+void ARMELFStreamer::reset() {
+  MCTargetStreamer &TS = *getTargetStreamer();
+  ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
+  ATS.reset();
+  MappingSymbolCounter = 0;
+  MCELFStreamer::reset();
+  // MCELFStreamer clear's the assembler's e_flags. However, for
+  // arm we manually set the ABI version on streamer creation, so
+  // do the same here
+  getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
+}
+
 inline void ARMELFStreamer::SwitchToEHSection(const char *Prefix,
                                               unsigned Type,
                                               unsigned Flags,
@@ -1094,7 +1114,7 @@
                                               Kind));
 }
 
-void ARMELFStreamer::Reset() {
+void ARMELFStreamer::EHReset() {
   ExTab = nullptr;
   FnStart = nullptr;
   Personality = nullptr;
@@ -1164,7 +1184,7 @@
   SwitchSection(&FnStart->getSection());
 
   // Clean exception handling frame information
-  Reset();
+  EHReset();
 }
 
 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
Index: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
@@ -38,6 +38,9 @@
 // finish() - write out any non-empty assembler constant pools.
 void ARMTargetStreamer::finish() { ConstantPools->emitAll(Streamer); }
 
+// reset() - Reset any state
+void ARMTargetStreamer::reset() {}
+
 // The remaining callbacks should be handled separately by each
 // streamer.
 void ARMTargetStreamer::emitFnStart() {}
Index: llvm/trunk/test/MC/ARM/twice.ll
===================================================================
--- llvm/trunk/test/MC/ARM/twice.ll
+++ llvm/trunk/test/MC/ARM/twice.ll
@@ -0,0 +1,9 @@
+; Check for state persistence bugs in the ARM MC backend
+; This should neither fail (in the comparison that the second object
+; is bit-identical to the first) nor crash. Either failure would most
+; likely indicate some state that is not properly reset in the
+; appropriate ::reset method.
+; RUN: llc -compile-twice -filetype=obj %s -o -
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv4t-unknown-linux-gnueabi"