Index: llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -79,6 +79,7 @@
 
     bool eliminateIdentitySCEV(Instruction *UseInst, Instruction *IVOperand);
     bool replaceIVUserWithLoopInvariant(Instruction *UseInst);
+    bool replaceFloatIVWithIntegerIV(Instruction *UseInst, Value *IVOperand);
 
     bool eliminateOverflowIntrinsic(WithOverflowInst *WO);
     bool eliminateSaturatingIntrinsic(SaturatingInst *SI);
@@ -673,6 +674,35 @@
   return true;
 }
 
+/// Eliminate redundant type cast between integer and float.
+bool SimplifyIndvar::replaceFloatIVWithIntegerIV(Instruction *UseInst,
+                                                 Value *IVOperand) {
+  if (UseInst->getOpcode() != CastInst::SIToFP)
+    return false;
+
+  // Get the symbolic expression for this instruction.
+  ConstantRange IVRange = SE->getSignedRange(SE->getSCEV(IVOperand));
+  unsigned DestNumSigBits = UseInst->getType()->getFPMantissaWidth();
+  if (IVRange.getActiveBits() <= DestNumSigBits) {
+
+    for (User *U : UseInst->users()) {
+      // Match for fptosi of sitofp and with same type.
+      auto *CI = dyn_cast<FPToSIInst>(U);
+      if (!CI || IVOperand->getType() != CI->getType())
+        continue;
+
+      CI->replaceAllUsesWith(IVOperand);
+      LLVM_DEBUG(dbgs() << "INDVARS: Replace IV user: " << *CI
+                        << " with: " << *IVOperand << '\n');
+
+      ++NumFoldedUser;
+      Changed |= true;
+    }
+  }
+
+  return Changed;
+}
+
 /// Eliminate any operation that SCEV can prove is an identity function.
 bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
                                            Instruction *IVOperand) {
@@ -896,6 +926,10 @@
       }
     }
 
+    // Try to use integer induction for FPToSI of float induction Directly.
+    if (replaceFloatIVWithIntegerIV(UseInst, IVOperand))
+      continue;
+
     CastInst *Cast = dyn_cast<CastInst>(UseInst);
     if (V && Cast) {
       V->visitCast(Cast);
Index: llvm/test/Transforms/IndVarSimplify/floating-point-iv.ll
===================================================================
--- llvm/test/Transforms/IndVarSimplify/floating-point-iv.ll
+++ llvm/test/Transforms/IndVarSimplify/floating-point-iv.ll
@@ -377,7 +377,7 @@
 ; CHECK-NEXT:    [[FLOAT_IV_INT:%.*]] = phi i32 [ 1000, [[ENTRY:%.*]] ], [ [[FLOAT_IV_NEXT_INT:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[INDVAR_CONV:%.*]] = sitofp i32 [[FLOAT_IV_INT]] to float
 ; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[INDVAR_CONV]] to i32
-; CHECK-NEXT:    [[IDXPROM:%.*]] = sext i32 [[CONV]] to i64
+; CHECK-NEXT:    [[IDXPROM:%.*]] = sext i32 [[FLOAT_IV_INT]] to i64
 ; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[DST:%.*]], i64 [[IDXPROM]]
 ; CHECK-NEXT:    store float [[INDVAR_CONV]], ptr [[ARRAYIDX]], align 4
 ; CHECK-NEXT:    [[FLOAT_IV_NEXT_INT]] = add nsw i32 [[FLOAT_IV_INT]], -1
Index: llvm/test/Transforms/IndVarSimplify/floating-point-small-iv.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/IndVarSimplify/floating-point-small-iv.ll
@@ -0,0 +1,37 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -indvars -adce -S | FileCheck %s
+
+@array = dso_local global [101 x i32] zeroinitializer, align 4
+
+define void @small_const_bound(i32 %index) {
+; CHECK-LABEL: @small_const_bound(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[I_010_INT:%.*]] = phi i32 [ 100, [[ENTRY:%.*]] ], [ [[DEC_INT:%.*]], [[FOR_BODY]] ]
+; CHECK-NEXT:    [[IDXPROM:%.*]] = sext i32 [[I_010_INT]] to i64
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [101 x i32], [101 x i32]* @array, i64 0, i64 [[IDXPROM]]
+; CHECK-NEXT:    store i32 [[I_010_INT]], i32* [[ARRAYIDX]], align 4
+; CHECK-NEXT:    [[DEC_INT]] = add nsw i32 [[I_010_INT]], -1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[DEC_INT]], 0
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[CLEANUP:%.*]]
+; CHECK:       cleanup:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.010 = phi float [ 1.000000e+02, %entry ], [ %dec, %for.body ]
+  %conv = fptosi float %i.010 to i32
+  %idxprom = sext i32 %conv to i64
+  %arrayidx = getelementptr inbounds [101 x i32], [101 x i32]* @array, i64 0, i64 %idxprom
+  store i32 %conv, i32* %arrayidx, align 4
+  %dec = fadd fast float %i.010, -1.000000e+00
+  %cmp = fcmp fast ogt float %dec, 0.000000e+00
+  br i1 %cmp, label %for.body, label %cleanup
+
+cleanup:                                 ; preds = %for.body
+  ret void
+}
+