diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -161,6 +161,15 @@
   bool enableSaveRestore() const { return EnableSaveRestore; }
   MVT getXLenVT() const { return XLenVT; }
   unsigned getXLen() const { return XLen; }
+  unsigned getFLen() const {
+    if (HasStdExtD)
+      return 64;
+
+    if (HasStdExtF)
+      return 32;
+
+    return 0;
+  }
   RISCVABI::ABI getTargetABI() const { return TargetABI; }
   bool isRegisterReservedByUser(Register i) const {
     assert(i < RISCV::NUM_TARGET_REGS && "Register out of range");
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
@@ -60,6 +60,8 @@
 
   TypeSize getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const;
 
+  InstructionCost getRegUsageForType(Type *Ty);
+
   void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                TTI::UnrollingPreferences &UP,
                                OptimizationRemarkEmitter *ORE);
@@ -176,6 +178,20 @@
     // Let regular unroll to unroll the loop.
     return VF == 1 ? 1 : ST->getMaxInterleaveFactor();
   }
+
+  // TODO: We should define RISC-V's own register classes.
+  //       e.g. register class for FPR.
+  unsigned getNumberOfRegisters(unsigned ClassID) const {
+    bool Vector = (ClassID == 1);
+    if (Vector) {
+      if (ST->hasVInstructions())
+        return 32;
+      return 0;
+    }
+    // 31 = 32 GPR - x0 (zero register)
+    // FIXME: Should we exclude fixed registers like SP, TP or GP?
+    return 31;
+  }
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -275,3 +275,16 @@
                                          TTI::PeelingPreferences &PP) {
   BaseT::getPeelingPreferences(L, SE, PP);
 }
+
+InstructionCost RISCVTTIImpl::getRegUsageForType(Type *Ty) {
+  TypeSize Size = Ty->getPrimitiveSizeInBits();
+  if (Ty->isVectorTy()) {
+    if (Size.isScalable() && ST->hasVInstructions())
+      return divideCeil(Size.getKnownMinValue(), RISCV::RVVBitsPerBlock);
+
+    if (ST->useRVVForFixedLengthVectors())
+      return divideCeil(Size, ST->getMinRVVVectorSizeInBits());
+  }
+
+  return BaseT::getRegUsageForType(Ty);
+}
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/reg-usage.ll b/llvm/test/Transforms/LoopVectorize/RISCV/reg-usage.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/reg-usage.ll
@@ -0,0 +1,62 @@
+; REQUIRES: asserts
+; RUN: opt -loop-vectorize -mtriple riscv64-linux-gnu \
+; RUN:   -mattr=+experimental-v,+d -debug-only=loop-vectorize \
+; RUN:   -riscv-v-vector-bits-min=128 -riscv-v-register-bit-width-lmul=1 \
+; RUN:   -S < %s 2>&1 | FileCheck %s --check-prefix=CHECK-LMUL1
+; RUN: opt -loop-vectorize -mtriple riscv64-linux-gnu \
+; RUN:   -mattr=+experimental-v,+d -debug-only=loop-vectorize \
+; RUN:   -riscv-v-vector-bits-min=128 -riscv-v-register-bit-width-lmul=2 \
+; RUN:   -S < %s 2>&1 | FileCheck %s --check-prefix=CHECK-LMUL2
+; RUN: opt -loop-vectorize -mtriple riscv64-linux-gnu \
+; RUN:   -mattr=+experimental-v,+d -debug-only=loop-vectorize \
+; RUN:   -riscv-v-vector-bits-min=128 -riscv-v-register-bit-width-lmul=4 \
+; RUN:   -S < %s 2>&1 | FileCheck %s --check-prefix=CHECK-LMUL4
+; RUN: opt -loop-vectorize -mtriple riscv64-linux-gnu \
+; RUN:   -mattr=+experimental-v,+d -debug-only=loop-vectorize \
+; RUN:   -riscv-v-vector-bits-min=128 -riscv-v-register-bit-width-lmul=8 \
+; RUN:   -S < %s 2>&1 | FileCheck %s --check-prefix=CHECK-LMUL8
+
+define void @add(float* noalias nocapture readonly %src1, float* noalias nocapture readonly %src2, i32 signext %size, float* noalias nocapture writeonly %result) {
+; CHECK-LABEL: add
+; CHECK-LMUL1:      LV(REG): Found max usage: 2 item
+; CHECK-LMUL1-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 2 registers
+; CHECK-LMUL1-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 2 registers
+; CHECK-LMUL1-NEXT: LV(REG): Found invariant usage: 1 item
+; CHECK-LMUL1-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 2 registers
+; CHECK-LMUL2:      LV(REG): Found max usage: 2 item
+; CHECK-LMUL2-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 2 registers
+; CHECK-LMUL2-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 4 registers
+; CHECK-LMUL2-NEXT: LV(REG): Found invariant usage: 1 item
+; CHECK-LMUL2-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 4 registers
+; CHECK-LMUL4:      LV(REG): Found max usage: 2 item
+; CHECK-LMUL4-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 2 registers
+; CHECK-LMUL4-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 8 registers
+; CHECK-LMUL4-NEXT: LV(REG): Found invariant usage: 1 item
+; CHECK-LMUL4-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 8 registers
+; CHECK-LMUL8:      LV(REG): Found max usage: 2 item
+; CHECK-LMUL8-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 2 registers
+; CHECK-LMUL8-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 16 registers
+; CHECK-LMUL8-NEXT: LV(REG): Found invariant usage: 1 item
+; CHECK-LMUL8-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 16 registers
+
+entry:
+  %conv = zext i32 %size to i64
+  %cmp10.not = icmp eq i32 %size, 0
+  br i1 %cmp10.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %i.011 = phi i64 [ %add4, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds float, float* %src1, i64 %i.011
+  %0 = load float, float* %arrayidx, align 4
+  %arrayidx2 = getelementptr inbounds float, float* %src2, i64 %i.011
+  %1 = load float, float* %arrayidx2, align 4
+  %add = fadd float %0, %1
+  %arrayidx3 = getelementptr inbounds float, float* %result, i64 %i.011
+  store float %add, float* %arrayidx3, align 4
+  %add4 = add nuw nsw i64 %i.011, 1
+  %exitcond.not = icmp eq i64 %add4, %conv
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}