Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/MC/MCELFStreamer.h b/linux-x64/clang/include/llvm/MC/MCELFStreamer.h
new file mode 100644
index 0000000..2f23cd6
--- /dev/null
+++ b/linux-x64/clang/include/llvm/MC/MCELFStreamer.h
@@ -0,0 +1,102 @@
+//===- MCELFStreamer.h - MCStreamer ELF Object File Interface ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCELFSTREAMER_H
+#define LLVM_MC_MCELFSTREAMER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCObjectStreamer.h"
+
+namespace llvm {
+
+class MCAsmBackend;
+class MCCodeEmitter;
+class MCExpr;
+class MCInst;
+
+class MCELFStreamer : public MCObjectStreamer {
+public:
+  MCELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
+                raw_pwrite_stream &OS, std::unique_ptr<MCCodeEmitter> Emitter);
+
+  ~MCELFStreamer() override = default;
+
+  /// state management
+  void reset() override {
+    SeenIdent = false;
+    BundleGroups.clear();
+    MCObjectStreamer::reset();
+  }
+
+  /// \name MCStreamer Interface
+  /// @{
+
+  void InitSections(bool NoExecStack) override;
+  void ChangeSection(MCSection *Section, const MCExpr *Subsection) override;
+  void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
+  void EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F) override;
+  void EmitAssemblerFlag(MCAssemblerFlag Flag) override;
+  void EmitThumbFunc(MCSymbol *Func) override;
+  void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
+  bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
+  void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
+  void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                        unsigned ByteAlignment) override;
+
+  void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
+  void emitELFSymverDirective(StringRef AliasName,
+                              const MCSymbol *Aliasee) override;
+
+  void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                             unsigned ByteAlignment) override;
+
+  void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
+                    uint64_t Size = 0, unsigned ByteAlignment = 0) override;
+  void EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
+                      unsigned ByteAlignment = 0) override;
+  void EmitValueImpl(const MCExpr *Value, unsigned Size,
+                     SMLoc Loc = SMLoc()) override;
+
+  void EmitIdent(StringRef IdentString) override;
+
+  void EmitValueToAlignment(unsigned, int64_t, unsigned, unsigned) override;
+
+  void FinishImpl() override;
+
+  void EmitBundleAlignMode(unsigned AlignPow2) override;
+  void EmitBundleLock(bool AlignToEnd) override;
+  void EmitBundleUnlock() override;
+
+private:
+  bool isBundleLocked() const;
+  void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &) override;
+  void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo &) override;
+
+  void fixSymbolsInTLSFixups(const MCExpr *expr);
+
+  /// \brief Merge the content of the fragment \p EF into the fragment \p DF.
+  void mergeFragment(MCDataFragment *, MCDataFragment *);
+
+  bool SeenIdent = false;
+
+  /// BundleGroups - The stack of fragments holding the bundle-locked
+  /// instructions.
+  SmallVector<MCDataFragment *, 4> BundleGroups;
+};
+
+MCELFStreamer *createARMELFStreamer(MCContext &Context,
+                                    std::unique_ptr<MCAsmBackend> TAB,
+                                    raw_pwrite_stream &OS,
+                                    std::unique_ptr<MCCodeEmitter> Emitter,
+                                    bool RelaxAll, bool IsThumb);
+
+} // end namespace llvm
+
+#endif // LLVM_MC_MCELFSTREAMER_H