diff --git a/llvm/utils/TableGen/PredicateExpander.cpp b/llvm/utils/TableGen/PredicateExpander.cpp
index 0882ab8..83f67c0 100644
--- a/llvm/utils/TableGen/PredicateExpander.cpp
+++ b/llvm/utils/TableGen/PredicateExpander.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "PredicateExpander.h"
+#include "CodeGenSchedule.h" // Definition of STIPredicateFunction.
 
 namespace llvm {
 
@@ -313,4 +314,158 @@
   llvm_unreachable("No known rules to expand this MCInstPredicate");
 }
 
+void STIPredicateExpander::expandHeader(raw_ostream &OS,
+                                        const STIPredicateFunction &Fn) {
+  const Record *Rec = Fn.getDeclaration();
+  StringRef FunctionName = Rec->getValueAsString("Name");
+
+  OS.indent(getIndentLevel() * 2);
+  OS << "bool ";
+  if (shouldExpandDefinition())
+    OS << getClassPrefix() << "::";
+  OS << FunctionName << "(";
+  if (shouldExpandForMC())
+    OS << "const MCInst " << (isByRef() ? "&" : "*") << "MI";
+  else
+    OS << "const MachineInstr " << (isByRef() ? "&" : "*") << "MI";
+  if (Rec->getValueAsBit("UpdatesOpcodeMask"))
+    OS << ", APInt &Mask";
+  OS << (shouldExpandForMC() ? ", unsigned ProcessorID) const " : ") const ");
+  if (shouldExpandDefinition()) {
+    OS << "{\n";
+    return;
+  }
+
+  if (Rec->getValueAsBit("OverridesBaseClassMember"))
+    OS << "override";
+  OS << ";\n";
+}
+
+void STIPredicateExpander::expandPrologue(raw_ostream &OS,
+                                          const STIPredicateFunction &Fn) {
+  RecVec Delegates = Fn.getDeclaration()->getValueAsListOfDefs("Delegates");
+  bool UpdatesOpcodeMask =
+      Fn.getDeclaration()->getValueAsBit("UpdatesOpcodeMask");
+
+  increaseIndentLevel();
+  unsigned IndentLevel = getIndentLevel();
+  for (const Record *Delegate : Delegates) {
+    OS.indent(IndentLevel * 2);
+    OS << "if (" << Delegate->getValueAsString("Name") << "(MI";
+    if (UpdatesOpcodeMask)
+      OS << ", Mask";
+    if (shouldExpandForMC())
+      OS << ", ProcessorID";
+    OS << "))\n";
+    OS.indent((1 + IndentLevel) * 2);
+    OS << "return true;\n\n";
+  }
+
+  if (shouldExpandForMC())
+    return;
+
+  OS.indent(IndentLevel * 2);
+  OS << "unsigned ProcessorID = getSchedModel().getProcessorID();\n";
+}
+
+void STIPredicateExpander::expandOpcodeGroup(raw_ostream &OS, const OpcodeGroup &Group,
+                                             bool ShouldUpdateOpcodeMask) {
+  const OpcodeInfo &OI = Group.getOpcodeInfo();
+  for (const PredicateInfo &PI : OI.getPredicates()) {
+    const APInt &ProcModelMask = PI.ProcModelMask;
+    bool FirstProcID = true;
+    for (unsigned I = 0, E = ProcModelMask.getActiveBits(); I < E; ++I) {
+      if (!ProcModelMask[I])
+        continue;
+
+      if (FirstProcID) {
+        OS.indent(getIndentLevel() * 2);
+        OS << "if (ProcessorID == " << I;
+      } else {
+        OS << " || ProcessorID == " << I;
+      }
+      FirstProcID = false;
+    }
+
+    OS << ") {\n";
+
+    increaseIndentLevel();
+    OS.indent(getIndentLevel() * 2);
+    if (ShouldUpdateOpcodeMask) {
+      if (PI.OperandMask.isNullValue())
+        OS << "Mask.clearAllBits();\n";
+      else
+        OS << "Mask = " << PI.OperandMask << ";\n";
+      OS.indent(getIndentLevel() * 2);
+    }
+    OS << "return ";
+    expandPredicate(OS, PI.Predicate);
+    OS << ";\n";
+    decreaseIndentLevel();
+    OS.indent(getIndentLevel() * 2);
+    OS << "}\n";
+  }
+}
+
+void STIPredicateExpander::expandBody(raw_ostream &OS,
+                                      const STIPredicateFunction &Fn) {
+  bool UpdatesOpcodeMask =
+      Fn.getDeclaration()->getValueAsBit("UpdatesOpcodeMask");
+
+  unsigned IndentLevel = getIndentLevel();
+  OS.indent(IndentLevel * 2);
+  OS << "switch(MI" << (isByRef() ? "." : "->") << "getOpcode()) {\n";
+  OS.indent(IndentLevel * 2);
+  OS << "default:\n";
+  OS.indent(IndentLevel * 2);
+  OS << "  break;";
+
+  for (const OpcodeGroup &Group : Fn.getGroups()) {
+    for (const Record *Opcode : Group.getOpcodes()) {
+      OS << '\n';
+      OS.indent(IndentLevel * 2);
+      OS << "case " << getTargetName() << "::" << Opcode->getName() << ":";
+    }
+
+    OS << '\n';
+    increaseIndentLevel();
+    expandOpcodeGroup(OS, Group, UpdatesOpcodeMask);
+
+    OS.indent(getIndentLevel() * 2);
+    OS << "break;\n";
+    decreaseIndentLevel();
+  }
+
+  OS.indent(IndentLevel * 2);
+  OS << "}\n";
+}
+
+void STIPredicateExpander::expandEpilogue(raw_ostream &OS,
+                                          const STIPredicateFunction &Fn) {
+  OS << '\n';
+  OS.indent(getIndentLevel() * 2);
+  OS << "return ";
+  expandPredicate(OS, Fn.getDefaultReturnPredicate());
+  OS << ";\n";
+
+  decreaseIndentLevel();
+  OS.indent(getIndentLevel() * 2);
+  StringRef FunctionName = Fn.getDeclaration()->getValueAsString("Name");
+  OS << "} // " << ClassPrefix << "::" << FunctionName << "\n\n";
+}
+
+void STIPredicateExpander::expandSTIPredicate(raw_ostream &OS,
+                                              const STIPredicateFunction &Fn) {
+  const Record *Rec = Fn.getDeclaration();
+  if (shouldExpandForMC() && !Rec->getValueAsBit("ExpandForMC"))
+    return;
+
+  expandHeader(OS, Fn);
+  if (shouldExpandDefinition()) {
+    expandPrologue(OS, Fn);
+    expandBody(OS, Fn);
+    expandEpilogue(OS, Fn);
+  }
+}
+
 } // namespace llvm