Index: llvm/trunk/include/llvm/CodeGen/TargetPassConfig.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/TargetPassConfig.h
+++ llvm/trunk/include/llvm/CodeGen/TargetPassConfig.h
@@ -317,10 +317,6 @@
   /// verification is enabled.
   void addVerifyPass(const std::string &Banner);
 
-  /// Check whether or not GlobalISel should be enabled by default.
-  /// Fallback/abort behavior is controlled via other methods.
-  virtual bool isGlobalISelEnabled() const;
-
   /// Check whether or not GlobalISel should abort on error.
   /// When this is disabled, GlobalISel will fall back on SDISel instead of
   /// erroring out.
Index: llvm/trunk/include/llvm/Target/TargetMachine.h
===================================================================
--- llvm/trunk/include/llvm/Target/TargetMachine.h
+++ llvm/trunk/include/llvm/Target/TargetMachine.h
@@ -184,6 +184,7 @@
   void setFastISel(bool Enable) { Options.EnableFastISel = Enable; }
   bool getO0WantsFastISel() { return O0WantsFastISel; }
   void setO0WantsFastISel(bool Enable) { O0WantsFastISel = Enable; }
+  void setGlobalISel(bool Enable) { Options.EnableGlobalISel = Enable; }
 
   bool shouldPrintMachineCode() const { return Options.PrintMachineCode; }
 
Index: llvm/trunk/include/llvm/Target/TargetOptions.h
===================================================================
--- llvm/trunk/include/llvm/Target/TargetOptions.h
+++ llvm/trunk/include/llvm/Target/TargetOptions.h
@@ -104,7 +104,7 @@
           NoSignedZerosFPMath(false),
           HonorSignDependentRoundingFPMathOption(false), NoZerosInBSS(false),
           GuaranteedTailCallOpt(false), StackSymbolOrdering(true),
-          EnableFastISel(false), UseInitArray(false),
+          EnableFastISel(false), EnableGlobalISel(false), UseInitArray(false),
           DisableIntegratedAS(false), RelaxELFRelocations(false),
           FunctionSections(false), DataSections(false),
           UniqueSectionNames(true), TrapUnreachable(false), EmulatedTLS(false),
@@ -186,6 +186,9 @@
     /// compile time.
     unsigned EnableFastISel : 1;
 
+    /// EnableGlobalISel - This flag enables global instruction selection.
+    unsigned EnableGlobalISel : 1;
+
     /// UseInitArray - Use .init_array instead of .ctors for static
     /// constructors.
     unsigned UseInitArray : 1;
Index: llvm/trunk/lib/CodeGen/TargetPassConfig.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/TargetPassConfig.cpp
+++ llvm/trunk/lib/CodeGen/TargetPassConfig.cpp
@@ -123,9 +123,9 @@
 EnableFastISelOption("fast-isel", cl::Hidden,
   cl::desc("Enable the \"fast\" instruction selector"));
 
-static cl::opt<cl::boolOrDefault>
-    EnableGlobalISel("global-isel", cl::Hidden,
-                     cl::desc("Enable the \"global\" instruction selector"));
+static cl::opt<cl::boolOrDefault> EnableGlobalISelOption(
+    "global-isel", cl::Hidden,
+    cl::desc("Enable the \"global\" instruction selector"));
 
 static cl::opt<std::string> PrintMachineInstrs(
     "print-machineinstrs", cl::ValueOptional, cl::desc("Print machine instrs"),
@@ -704,19 +704,23 @@
 }
 
 bool TargetPassConfig::addCoreISelPasses() {
-  // Enable FastISel with -fast, but allow that to be overridden.
+  // Enable FastISel with -fast-isel, but allow that to be overridden.
   TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
   if (EnableFastISelOption == cl::BOU_TRUE ||
       (TM->getOptLevel() == CodeGenOpt::None && TM->getO0WantsFastISel()))
     TM->setFastISel(true);
 
-  // Ask the target for an isel.
-  // Enable GlobalISel if the target wants to, but allow that to be overriden.
+  // Ask the target for an instruction selector.
+  bool EnableGlobalISel = TM->Options.EnableGlobalISel;
   // Explicitly enabling fast-isel should override implicitly enabled
   // global-isel.
-  if (EnableGlobalISel == cl::BOU_TRUE ||
-      (EnableGlobalISel == cl::BOU_UNSET && isGlobalISelEnabled() &&
-       EnableFastISelOption != cl::BOU_TRUE)) {
+  if (EnableGlobalISel && (EnableGlobalISelOption == cl::BOU_UNSET) &&
+      (EnableFastISelOption == cl::BOU_TRUE))
+    EnableGlobalISel = false;
+  if (EnableGlobalISelOption == cl::BOU_TRUE)
+    EnableGlobalISel = true;
+
+  if (EnableGlobalISel) {
     if (addIRTranslator())
       return true;
 
@@ -1130,18 +1134,13 @@
 //===---------------------------------------------------------------------===//
 /// GlobalISel Configuration
 //===---------------------------------------------------------------------===//
-
-bool TargetPassConfig::isGlobalISelEnabled() const {
-  return false;
-}
-
 bool TargetPassConfig::isGlobalISelAbortEnabled() const {
   if (EnableGlobalISelAbort.getNumOccurrences() > 0)
     return EnableGlobalISelAbort == 1;
 
   // When no abort behaviour is specified, we don't abort if the target says
   // that GISel is enabled.
-  return !isGlobalISelEnabled();
+  return !TM->Options.EnableGlobalISel;
 }
 
 bool TargetPassConfig::reportDiagnosticWhenGlobalISelFallback() const {
Index: llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -243,6 +243,10 @@
                         getEffectiveCodeModel(TT, CM, JIT), OL),
       TLOF(createTLOF(getTargetTriple())), isLittle(LittleEndian) {
   initAsmInfo();
+
+  // Enable GlobalISel at or below EnableGlobalISelAt0.
+  if (getOptLevel() <= EnableGlobalISelAtO)
+    setGlobalISel(true);
 }
 
 AArch64TargetMachine::~AArch64TargetMachine() = default;
@@ -340,8 +344,6 @@
   void addPostRegAlloc() override;
   void addPreSched2() override;
   void addPreEmitPass() override;
-
-  bool isGlobalISelEnabled() const override;
 };
 
 } // end anonymous namespace
@@ -455,10 +457,6 @@
   return false;
 }
 
-bool AArch64PassConfig::isGlobalISelEnabled() const {
-  return TM->getOptLevel() <= EnableGlobalISelAtO;
-}
-
 bool AArch64PassConfig::addILPOpts() {
   if (EnableCondOpt)
     addPass(createAArch64ConditionOptimizerPass());