Index: lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.h
===================================================================
--- lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.h
+++ lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.h
@@ -35,7 +35,7 @@
   // The size of co-processor 2 registers.
   Mips::AFL_REG CPR2Size;
   // Processor-specific extension.
-  uint32_t ISAExtensionSet;
+  Mips::AFL_EXT ISAExtension;
   // Mask of ASEs used.
   uint32_t ASESet;
 
@@ -51,8 +51,8 @@
   MipsABIFlagsSection()
       : Version(0), ISALevel(0), ISARevision(0), GPRSize(Mips::AFL_REG_NONE),
         CPR1Size(Mips::AFL_REG_NONE), CPR2Size(Mips::AFL_REG_NONE),
-        ISAExtensionSet(0), ASESet(0), OddSPReg(false), Is32BitABI(false),
-        FpABI(FpABIKind::ANY) {}
+        ISAExtension(Mips::AFL_EXT_NONE), ASESet(0), OddSPReg(false),
+        Is32BitABI(false), FpABI(FpABIKind::ANY) {}
 
   uint16_t getVersionValue() { return (uint16_t)Version; }
   uint8_t getISALevelValue() { return (uint8_t)ISALevel; }
@@ -61,7 +61,7 @@
   uint8_t getCPR1SizeValue();
   uint8_t getCPR2SizeValue() { return (uint8_t)CPR2Size; }
   uint8_t getFpABIValue();
-  uint32_t getISAExtensionSetValue() { return (uint32_t)ISAExtensionSet; }
+  uint32_t getISAExtensionValue() { return (uint32_t)ISAExtension; }
   uint32_t getASESetValue() { return (uint32_t)ASESet; }
 
   uint32_t getFlags1Value() {
@@ -141,6 +141,14 @@
   }
 
   template <class PredicateLibrary>
+  void setISAExtensionFromPredicates(const PredicateLibrary &P) {
+    if (P.hasCnMips())
+      ISAExtension = Mips::AFL_EXT_OCTEON;
+    else
+      ISAExtension = Mips::AFL_EXT_NONE;
+  }
+
+  template <class PredicateLibrary>
   void setASESetFromPredicates(const PredicateLibrary &P) {
     ASESet = 0;
     if (P.hasDSP())
@@ -179,6 +187,7 @@
     setISALevelAndRevisionFromPredicates(P);
     setGPRSizeFromPredicates(P);
     setCPR1SizeFromPredicates(P);
+    setISAExtensionFromPredicates(P);
     setASESetFromPredicates(P);
     setFpAbiFromPredicates(P);
     OddSPReg = P.useOddSPReg();
Index: lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.cpp
===================================================================
--- lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.cpp
+++ lib/Target/Mips/MCTargetDesc/MipsABIFlagsSection.cpp
@@ -53,17 +53,17 @@
 namespace llvm {
 MCStreamer &operator<<(MCStreamer &OS, MipsABIFlagsSection &ABIFlagsSection) {
   // Write out a Elf_Internal_ABIFlags_v0 struct
-  OS.EmitIntValue(ABIFlagsSection.getVersionValue(), 2);         // version
-  OS.EmitIntValue(ABIFlagsSection.getISALevelValue(), 1);        // isa_level
-  OS.EmitIntValue(ABIFlagsSection.getISARevisionValue(), 1);     // isa_rev
-  OS.EmitIntValue(ABIFlagsSection.getGPRSizeValue(), 1);         // gpr_size
-  OS.EmitIntValue(ABIFlagsSection.getCPR1SizeValue(), 1);        // cpr1_size
-  OS.EmitIntValue(ABIFlagsSection.getCPR2SizeValue(), 1);        // cpr2_size
-  OS.EmitIntValue(ABIFlagsSection.getFpABIValue(), 1);           // fp_abi
-  OS.EmitIntValue(ABIFlagsSection.getISAExtensionSetValue(), 4); // isa_ext
-  OS.EmitIntValue(ABIFlagsSection.getASESetValue(), 4);          // ases
-  OS.EmitIntValue(ABIFlagsSection.getFlags1Value(), 4);          // flags1
-  OS.EmitIntValue(ABIFlagsSection.getFlags2Value(), 4);          // flags2
+  OS.EmitIntValue(ABIFlagsSection.getVersionValue(), 2);      // version
+  OS.EmitIntValue(ABIFlagsSection.getISALevelValue(), 1);     // isa_level
+  OS.EmitIntValue(ABIFlagsSection.getISARevisionValue(), 1);  // isa_rev
+  OS.EmitIntValue(ABIFlagsSection.getGPRSizeValue(), 1);      // gpr_size
+  OS.EmitIntValue(ABIFlagsSection.getCPR1SizeValue(), 1);     // cpr1_size
+  OS.EmitIntValue(ABIFlagsSection.getCPR2SizeValue(), 1);     // cpr2_size
+  OS.EmitIntValue(ABIFlagsSection.getFpABIValue(), 1);        // fp_abi
+  OS.EmitIntValue(ABIFlagsSection.getISAExtensionValue(), 4); // isa_ext
+  OS.EmitIntValue(ABIFlagsSection.getASESetValue(), 4);       // ases
+  OS.EmitIntValue(ABIFlagsSection.getFlags1Value(), 4);       // flags1
+  OS.EmitIntValue(ABIFlagsSection.getFlags2Value(), 4);       // flags2
   return OS;
 }
 }
Index: lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
===================================================================
--- lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -705,6 +705,10 @@
   else
     EFlags |= ELF::EF_MIPS_ARCH_1;
 
+  // Machine
+  if (Features[Mips::FeatureCnMips])
+    EFlags |= ELF::EF_MIPS_MACH_OCTEON;
+
   // Other options.
   if (Features[Mips::FeatureNaN2008])
     EFlags |= ELF::EF_MIPS_NAN2008;
Index: test/MC/Mips/elf_eflags.s
===================================================================
--- test/MC/Mips/elf_eflags.s
+++ test/MC/Mips/elf_eflags.s
@@ -125,3 +125,6 @@
 
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-NAN2008 %s
 # MIPS64EL-MIPS64-NAN2008: Flags [ (0x60000406)
+
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=octeon %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-OCTEON %s
+# MIPSEL-OCTEON: Flags [ (0x808B0006)
Index: test/MC/Mips/mips_abi_flags_xx.s
===================================================================
--- test/MC/Mips/mips_abi_flags_xx.s
+++ test/MC/Mips/mips_abi_flags_xx.s
@@ -3,22 +3,30 @@
 #
 # RUN: llvm-mc %s -arch=mips -mcpu=mips32 -filetype=obj -o - | \
 # RUN:   llvm-readobj -sections -section-data -section-relocations -mips-abi-flags - | \
-# RUN:     FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-R1
+# RUN:   FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-32R1 \
+# RUN:   -check-prefix=CHECK-OBJ-MIPS
 
 # RUN: llvm-mc /dev/null -arch=mips -mcpu=mips32 -mattr=fpxx -filetype=obj -o - | \
 # RUN:   llvm-readobj -sections -section-data -section-relocations -mips-abi-flags - | \
-# RUN:     FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-R1
+# RUN:   FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-32R1 \
+# RUN:   -check-prefix=CHECK-OBJ-MIPS
 
 # RUN: llvm-mc /dev/null -arch=mips -mcpu=mips32r6 -mattr=fpxx -filetype=obj -o - | \
 # RUN:   llvm-readobj -sections -section-data -section-relocations -mips-abi-flags - | \
-# RUN:     FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-R6
+# RUN:   FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-32R6 \
+# RUN:   -check-prefix=CHECK-OBJ-MIPS
+
+# RUN: llvm-mc /dev/null -arch=mips -mcpu=octeon -filetype=obj -o - | \
+# RUN:   llvm-readobj -sections -section-data -section-relocations -mips-abi-flags - | \
+# RUN:   FileCheck %s -check-prefix=CHECK-OBJ -check-prefix=CHECK-OBJ-64R2 \
+# RUN:   -check-prefix=CHECK-OBJ-OCTEON
 
 # CHECK-ASM: .module fp=xx
 
 # Checking if the Mips.abiflags were correctly emitted.
 # CHECK-OBJ:       Section {
 # CHECK-OBJ:         Index: 5
-# CHECK-OBJ-LABEL:   Name: .MIPS.abiflags (12)
+# CHECK-OBJ-LABEL:   Name: .MIPS.abiflags
 # CHECK-OBJ:         Type: SHT_MIPS_ABIFLAGS (0x7000002A)
 # CHECK-OBJ:          Flags [ (0x2)
 # CHECK-OBJ:           SHF_ALLOC (0x2)
@@ -34,14 +42,22 @@
 # CHECK-OBJ-LABEL: }
 # CHECK-OBJ:       MIPS ABI Flags {
 # CHECK-OBJ-NEXT:    Version: 0
-# CHECK-OBJ-R1-NEXT: ISA: {{MIPS32$}}
-# CHECK-OBJ-R6-NEXT: ISA: MIPS32r6
-# CHECK-OBJ-NEXT:    ISA Extension: None (0x0)
-# CHECK-OBJ-NEXT:    ASEs [ (0x0)
-# CHECK-OBJ-NEXT:    ]
-# CHECK-OBJ-NEXT:    FP ABI: Hard float (32-bit CPU, Any FPU) (0x5)
-# CHECK-OBJ-NEXT:    GPR size: 32
-# CHECK-OBJ-NEXT:    CPR1 size: 32
+# CHECK-OBJ-32R1-NEXT: ISA: {{MIPS32$}}
+# CHECK-OBJ-32R6-NEXT: ISA: MIPS32r6
+# CHECK-OBJ-64R2-NEXT: ISA: MIPS64r2
+# CHECK-OBJ-MIPS-NEXT:   ISA Extension: None (0x0)
+# CHECK-OBJ-OCTEON-NEXT: ISA Extension: Cavium Networks Octeon (0x5)
+# CHECK-OBJ-NEXT:    ASEs [ (0x0)          
+# CHECK-OBJ-NEXT:    ]                     
+# CHECK-OBJ-32R1-NEXT: FP ABI: Hard float (32-bit CPU, Any FPU) (0x5)
+# CHECK-OBJ-32R6-NEXT: FP ABI: Hard float (32-bit CPU, Any FPU) (0x5)
+# CHECK-OBJ-64R2-NEXT: FP ABI: Hard float (double precision) (0x1)
+# CHECK-OBJ-32R1-NEXT: GPR size: 32
+# CHECK-OBJ-32R6-NEXT: GPR size: 32
+# CHECK-OBJ-64R2-NEXT: GPR size: 64
+# CHECK-OBJ-32R1-NEXT: CPR1 size: 32
+# CHECK-OBJ-32R6-NEXT: CPR1 size: 32
+# CHECK-OBJ-64R2-NEXT: CPR1 size: 64
 # CHECK-OBJ-NEXT:    CPR2 size: 0
 # CHECK-OBJ-NEXT:    Flags 1 [ (0x1)
 # CHECK-OBJ-NEXT:      ODDSPREG (0x1)