Index: lib/Target/Mips/Mips.td
===================================================================
--- lib/Target/Mips/Mips.td
+++ lib/Target/Mips/Mips.td
@@ -57,6 +57,8 @@
 // Mips Subtarget features                                                    //
 //===----------------------------------------------------------------------===//
 
+def FeatureABICalls    : SubtargetFeature<"abicalls", "IsABICallsbit", "true",
+                                "SVR4-style position-independent code.">;
 def FeatureGP64Bit     : SubtargetFeature<"gp64", "IsGP64bit", "true",
                                 "General Purpose Registers are 64-bit wide.">;
 def FeatureFP64Bit     : SubtargetFeature<"fp64", "IsFP64bit", "true",
Index: lib/Target/Mips/MipsAsmPrinter.cpp
===================================================================
--- lib/Target/Mips/MipsAsmPrinter.cpp
+++ lib/Target/Mips/MipsAsmPrinter.cpp
@@ -620,9 +620,7 @@
 }
 
 void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
-  // TODO: Need to add -mabicalls and -mno-abicalls flags.
-  // Currently we assume that -mabicalls is the default.
-  bool IsABICalls = true;
+  bool IsABICalls = Subtarget->isABICalls();
   if (IsABICalls) {
     getTargetStreamer().emitDirectiveAbiCalls();
     Reloc::Model RM = Subtarget->getRelocationModel();
Index: lib/Target/Mips/MipsRegisterInfo.cpp
===================================================================
--- lib/Target/Mips/MipsRegisterInfo.cpp
+++ lib/Target/Mips/MipsRegisterInfo.cpp
@@ -143,6 +143,12 @@
   for (unsigned I = 0; I < array_lengthof(ReservedGPR64); ++I)
     Reserved.set(ReservedGPR64[I]);
 
+  // For mno-abicalls, GP is a program invariant!
+  if (!Subtarget.isABICalls()) {
+    Reserved.set(Mips::GP);
+    Reserved.set(Mips::GP_64);
+  }
+
   if (Subtarget.isFP64bit()) {
     // Reserve all registers in AFGR64.
     for (RegIter Reg = Mips::AFGR64RegClass.begin(),
Index: lib/Target/Mips/MipsSubtarget.h
===================================================================
--- lib/Target/Mips/MipsSubtarget.h
+++ lib/Target/Mips/MipsSubtarget.h
@@ -56,6 +56,9 @@
   // floating point registers instead of only using even ones.
   bool IsSingleFloat;
 
+  // IsABICallsbit - SVR4-style position-independent code.
+  bool IsABICallsbit;
+
   // IsFP64bit - The target processor has 64-bit floating point registers.
   bool IsFP64bit;
 
@@ -178,6 +181,7 @@
   bool hasCnMips() const { return HasCnMips; }
 
   bool isLittle() const { return IsLittle; }
+  bool isABICalls() const { return IsABICallsbit; }
   bool isFP64bit() const { return IsFP64bit; }
   bool isNaN2008() const { return IsNaN2008bit; }
   bool isNotFP64bit() const { return !IsFP64bit; }
Index: lib/Target/Mips/MipsSubtarget.cpp
===================================================================
--- lib/Target/Mips/MipsSubtarget.cpp
+++ lib/Target/Mips/MipsSubtarget.cpp
@@ -79,13 +79,14 @@
                              Reloc::Model _RM, MipsTargetMachine *_TM)
     : MipsGenSubtargetInfo(TT, CPU, FS), MipsArchVersion(Mips32),
       MipsABI(UnknownABI), IsLittle(little), IsSingleFloat(false),
-      IsFP64bit(false), IsNaN2008bit(false), IsGP64bit(false), HasVFPU(false),
-      HasCnMips(false), IsLinux(true), HasMips3_32(false), HasMips3_32r2(false),
-      HasMips4_32(false), HasMips4_32r2(false), HasMips5_32r2(false),
-      InMips16Mode(false), InMips16HardFloat(Mips16HardFloat),
-      InMicroMipsMode(false), HasDSP(false), HasDSPR2(false),
-      AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16), HasMSA(false),
-      RM(_RM), OverrideMode(NoOverride), TM(_TM), TargetTriple(TT) {
+      IsABICallsbit(true), IsFP64bit(false), IsNaN2008bit(false),
+      IsGP64bit(false), HasVFPU(false), HasCnMips(false), IsLinux(true),
+      HasMips3_32(false), HasMips3_32r2(false), HasMips4_32(false),
+      HasMips4_32r2(false), HasMips5_32r2(false), InMips16Mode(false),
+      InMips16HardFloat(Mips16HardFloat), InMicroMipsMode(false), HasDSP(false),
+      HasDSPR2(false), AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16),
+      HasMSA(false), RM(_RM), OverrideMode(NoOverride), TM(_TM),
+      TargetTriple(TT) {
   std::string CPUName = CPU;
   CPUName = selectMipsCPU(TT, CPUName);