Index: lib/Target/RISCV/MCTargetDesc/CMakeLists.txt
===================================================================
--- lib/Target/RISCV/MCTargetDesc/CMakeLists.txt
+++ lib/Target/RISCV/MCTargetDesc/CMakeLists.txt
@@ -5,4 +5,6 @@
   RISCVMCCodeEmitter.cpp
   RISCVMCExpr.cpp
   RISCVMCTargetDesc.cpp
+  RISCVTargetStreamer.cpp
+  RISCVELFStreamer.cpp
 )
Index: lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.h
===================================================================
--- /dev/null
+++ lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.h
@@ -0,0 +1,24 @@
+//===-- RISCVELFStreamer.h - RISCV ELF Target Streamer ---------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_RISCVELFSTREAMER_H
+#define LLVM_LIB_TARGET_RISCV_RISCVELFSTREAMER_H
+
+#include "RISCVTargetStreamer.h"
+#include "llvm/MC/MCELFStreamer.h"
+
+namespace llvm {
+
+class RISCVTargetELFStreamer : public RISCVTargetStreamer {
+public:
+  MCELFStreamer &getStreamer();
+  RISCVTargetELFStreamer(MCStreamer &S, const MCSubtargetInfo &STI);
+};
+}
+#endif
Index: lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp
===================================================================
--- /dev/null
+++ lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp
@@ -0,0 +1,39 @@
+//===-- RISCVELFStreamer.cpp - RISCV ELF Target Streamer Methods ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides RISCV specific target streamer methods.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCVMCTargetDesc.h"
+#include "RISCVELFStreamer.h"
+#include "llvm/BinaryFormat/ELF.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+
+using namespace llvm;
+
+// This part is for ELF object output.
+RISCVTargetELFStreamer::RISCVTargetELFStreamer(MCStreamer &S,
+                                               const MCSubtargetInfo &STI)
+    : RISCVTargetStreamer(S) {
+  MCAssembler &MCA = getStreamer().getAssembler();
+
+  const FeatureBitset &Features = STI.getFeatureBits();
+
+  unsigned EFlags = MCA.getELFHeaderEFlags();
+
+  if (Features[RISCV::FeatureStdExtC])
+    EFlags |= ELF::EF_RISCV_RVC;
+
+  MCA.setELFHeaderEFlags(EFlags);
+}
+
+MCELFStreamer &RISCVTargetELFStreamer::getStreamer() {
+  return static_cast<MCELFStreamer &>(Streamer);
+}
Index: lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
===================================================================
--- lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
+++ lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
@@ -14,6 +14,8 @@
 #include "RISCVMCTargetDesc.h"
 #include "InstPrinter/RISCVInstPrinter.h"
 #include "RISCVMCAsmInfo.h"
+#include "RISCVELFStreamer.h"
+#include "RISCVTargetStreamer.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCInstrInfo.h"
@@ -67,6 +69,14 @@
   return new RISCVInstPrinter(MAI, MII, MRI);
 }
 
+static MCTargetStreamer *
+createRISCVObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
+  const Triple &TT = STI.getTargetTriple();
+  if (TT.isOSBinFormatELF())
+    return new RISCVTargetELFStreamer(S, STI);
+  return new RISCVTargetStreamer(S);
+}
+
 extern "C" void LLVMInitializeRISCVTargetMC() {
   for (Target *T : {&getTheRISCV32Target(), &getTheRISCV64Target()}) {
     TargetRegistry::RegisterMCAsmInfo(*T, createRISCVMCAsmInfo);
@@ -76,5 +86,7 @@
     TargetRegistry::RegisterMCCodeEmitter(*T, createRISCVMCCodeEmitter);
     TargetRegistry::RegisterMCInstPrinter(*T, createRISCVMCInstPrinter);
     TargetRegistry::RegisterMCSubtargetInfo(*T, createRISCVMCSubtargetInfo);
+    TargetRegistry::RegisterObjectTargetStreamer(
+        *T, createRISCVObjectTargetStreamer);
   }
 }
Index: lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.h
===================================================================
--- /dev/null
+++ lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.h
@@ -0,0 +1,22 @@
+//===-- RISCVTargetStreamer.h - RISCV Target Streamer ----------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_RISCVTARGETSTREAMER_H
+#define LLVM_LIB_TARGET_RISCV_RISCVTARGETSTREAMER_H
+
+#include "llvm/MC/MCStreamer.h"
+
+namespace llvm {
+
+class RISCVTargetStreamer : public MCTargetStreamer {
+public:
+  RISCVTargetStreamer(MCStreamer &S);
+};
+}
+#endif
Index: lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
===================================================================
--- /dev/null
+++ lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -0,0 +1,19 @@
+//===-- RISCVTargetStreamer.cpp - RISCV Target Streamer Methods -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides RISCV specific target streamer methods.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCVTargetStreamer.h"
+
+using namespace llvm;
+
+RISCVTargetStreamer::RISCVTargetStreamer(MCStreamer &S)
+    : MCTargetStreamer(S) {}
Index: test/MC/RISCV/elf-flags.s
===================================================================
--- /dev/null
+++ test/MC/RISCV/elf-flags.s
@@ -0,0 +1,13 @@
+# RUN: llvm-mc -triple=riscv32 -filetype=obj < %s | llvm-readobj -file-headers - | FileCheck -check-prefixes=CHECK-RVI %s
+# RUN: llvm-mc -triple=riscv64 -filetype=obj < %s | llvm-readobj -file-headers - | FileCheck -check-prefixes=CHECK-RVI %s
+# RUN: llvm-mc -triple=riscv32 -mattr=+c -filetype=obj < %s | llvm-readobj -file-headers - | FileCheck -check-prefixes=CHECK-RVIC %s
+# RUN: llvm-mc -triple=riscv64 -mattr=+c -filetype=obj < %s | llvm-readobj -file-headers - | FileCheck -check-prefixes=CHECK-RVIC %s
+
+# CHECK-RVI:       Flags [ (0x0)
+# CHECK-RVI-NEXT:  ]
+
+# CHECK-RVIC:       Flags [ (0x1)
+# CHECK-RVIC-NEXT:    EF_RISCV_RVC (0x1)
+# CHECK-RVIC-NEXT:  ]
+
+nop