diff --git a/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.h b/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.h
--- a/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.h
+++ b/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.h
@@ -32,6 +32,12 @@
 class RISCVRegisterBankInfo final : public RISCVGenRegisterBankInfo {
 public:
   RISCVRegisterBankInfo(unsigned HwMode);
+
+  const RegisterBank &getRegBankFromRegClass(const TargetRegisterClass &RC,
+                                             LLT Ty) const override;
+
+  const InstructionMapping &
+  getInstrMapping(const MachineInstr &MI) const override;
 };
 } // end namespace llvm
 #endif
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp b/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp
--- a/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp
@@ -12,6 +12,7 @@
 
 #include "RISCVRegisterBankInfo.h"
 #include "MCTargetDesc/RISCVMCTargetDesc.h"
+#include "RISCVSubtarget.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterBank.h"
 #include "llvm/CodeGen/RegisterBankInfo.h"
@@ -20,7 +21,111 @@
 #define GET_TARGET_REGBANK_IMPL
 #include "RISCVGenRegisterBank.inc"
 
+namespace llvm {
+namespace RISCV {
+
+RegisterBankInfo::PartialMapping PartMappings[] = {
+    {0, 32, GPRRegBank},
+    {0, 64, GPRRegBank}
+};
+
+enum PartialMappingIdx {
+  PMI_GPR32 = 0,
+  PMI_GPR64 = 1
+};
+
+RegisterBankInfo::ValueMapping ValueMappings[] = {
+    // Invalid value mapping.
+    {nullptr, 0},
+    // Maximum 3 GPR operands; 32 bit.
+    {&PartMappings[PMI_GPR32], 1},
+    {&PartMappings[PMI_GPR32], 1},
+    {&PartMappings[PMI_GPR32], 1},
+    // Maximum 3 GPR operands; 64 bit.
+    {&PartMappings[PMI_GPR64], 1},
+    {&PartMappings[PMI_GPR64], 1},
+    {&PartMappings[PMI_GPR64], 1}
+};
+
+enum ValueMappingsIdx {
+  InvalidIdx = 0,
+  GPR32Idx = 1,
+  GPR64Idx = 4
+};
+} // namespace RISCV
+} // namespace llvm
+
 using namespace llvm;
 
 RISCVRegisterBankInfo::RISCVRegisterBankInfo(unsigned HwMode)
     : RISCVGenRegisterBankInfo(HwMode) {}
+
+
+const RegisterBank &
+RISCVRegisterBankInfo::getRegBankFromRegClass(const TargetRegisterClass &RC,
+                                              LLT Ty) const {
+  switch (RC.getID()) {
+  default:
+    llvm_unreachable("Register class not supported");
+  case RISCV::GPRRegClassID:
+  case RISCV::GPRNoX0RegClassID:
+  case RISCV::GPRNoX0X2RegClassID:
+  case RISCV::GPRTCRegClassID:
+  case RISCV::GPRCRegClassID:
+  case RISCV::GPRC_and_GPRTCRegClassID:
+  case RISCV::GPRX0RegClassID:
+  case RISCV::SPRegClassID:
+    return getRegBank(RISCV::GPRRegBankID);
+  case RISCV::FPR32RegClassID:
+  case RISCV::FPR32CRegClassID:
+  case RISCV::FPR64RegClassID:
+  case RISCV::FPR64CRegClassID:
+    llvm_unreachable("Register class not supported");
+  }
+}
+
+const RegisterBankInfo::InstructionMapping &
+RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
+  const auto &Mapping = getInstrMappingImpl(MI);
+  if (Mapping.isValid())
+    return Mapping;
+
+  const MachineFunction &MF = *MI.getParent()->getParent();
+  bool IsRV64 = MF.getSubtarget<RISCVSubtarget>().is64Bit();
+
+  size_t NumOperands = MI.getNumOperands();
+  const ValueMapping *GPRValueMapping =
+      &RISCV::ValueMappings[IsRV64 ? RISCV::GPR64Idx : RISCV::GPR32Idx];
+  const ValueMapping *OperandsMapping = GPRValueMapping;
+  unsigned MappingID = DefaultMappingID;
+
+  switch (MI.getOpcode()) {
+  case TargetOpcode::G_ADD:
+  case TargetOpcode::G_SUB:
+  case TargetOpcode::G_SHL:
+  case TargetOpcode::G_ASHR:
+  case TargetOpcode::G_LSHR:
+  case TargetOpcode::G_AND:
+  case TargetOpcode::G_OR:
+  case TargetOpcode::G_XOR:
+  case TargetOpcode::G_MUL:
+  case TargetOpcode::G_SDIV:
+  case TargetOpcode::G_SREM:
+  case TargetOpcode::G_UDIV:
+  case TargetOpcode::G_UREM:
+  case TargetOpcode::G_UMULH:
+    break;
+  case TargetOpcode::G_CONSTANT:
+    OperandsMapping = getOperandsMapping({GPRValueMapping, nullptr});
+    break;
+  case TargetOpcode::G_ICMP:
+    OperandsMapping = getOperandsMapping(
+        {GPRValueMapping, nullptr, GPRValueMapping, GPRValueMapping});
+    break;
+  default:
+    return getInvalidInstructionMapping();
+  }
+
+  return getInstructionMapping(MappingID, /*Cost=*/1, OperandsMapping,
+                               NumOperands);
+}