diff --git a/llvm/include/llvm/CodeGen/MachinePassRegistry.def b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
--- a/llvm/include/llvm/CodeGen/MachinePassRegistry.def
+++ b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
@@ -44,6 +44,7 @@
 FUNCTION_PASS("ee-instrument", EntryExitInstrumenterPass, (false))
 FUNCTION_PASS("post-inline-ee-instrument", EntryExitInstrumenterPass, (true))
 FUNCTION_PASS("expand-large-div-rem", ExpandLargeDivRemPass, ())
+FUNCTION_PASS("expand-large-fp-convert", ExpandLargeFpConvertPass, ())
 FUNCTION_PASS("expand-reductions", ExpandReductionsPass, ())
 FUNCTION_PASS("expandvp", ExpandVectorPredicationPass, ())
 FUNCTION_PASS("lowerinvoke", LowerInvokePass, ())
diff --git a/llvm/include/llvm/CodeGen/Passes.h b/llvm/include/llvm/CodeGen/Passes.h
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -494,6 +494,9 @@
   // Expands large div/rem instructions.
   FunctionPass *createExpandLargeDivRemPass();
 
+  // Expands large div/rem instructions.
+  FunctionPass *createExpandLargeFpConvertPass();
+
   // This pass expands memcmp() to load/stores.
   FunctionPass *createExpandMemCmpPass();
 
diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
--- a/llvm/include/llvm/CodeGen/TargetLowering.h
+++ b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -1955,6 +1955,12 @@
     return MaxDivRemBitWidthSupported;
   }
 
+  /// Returns the size in bits of the maximum larget fp convert the backend
+  /// supports. Larger operations will be expanded by ExpandLargeFPConvert.
+  unsigned getMaxLargeFPConvertBitWidthSupported() const {
+    return MaxLargeFPConvertBitWidthSupported;
+  }
+
   /// Returns the size of the smallest cmpxchg or ll/sc instruction
   /// the backend supports.  Any smaller operations are widened in
   /// AtomicExpandPass.
@@ -2526,6 +2532,12 @@
     MaxDivRemBitWidthSupported = SizeInBits;
   }
 
+  /// Set the size in bits of the maximum fp convert the backend supports.
+  /// Larger operations will be expanded by ExpandLargeFPConvert.
+  void setMaxLargeFPConvertBitWidthSupported(unsigned SizeInBits) {
+    MaxLargeFPConvertBitWidthSupported = SizeInBits;
+  }
+
   /// Sets the minimum cmpxchg or ll/sc size supported by the backend.
   void setMinCmpXchgSizeInBits(unsigned SizeInBits) {
     MinCmpXchgSizeInBits = SizeInBits;
@@ -3245,6 +3257,10 @@
   /// Larger operations will be expanded by ExpandLargeDivRem.
   unsigned MaxDivRemBitWidthSupported;
 
+  /// Size in bits of the maximum larget fp convert size the backend
+  /// supports. Larger operations will be expanded by ExpandLargeFPConvert.
+  unsigned MaxLargeFPConvertBitWidthSupported;
+
   /// Size in bits of the minimum cmpxchg or ll/sc operation the
   /// backend supports.
   unsigned MinCmpXchgSizeInBits;
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -134,6 +134,7 @@
 void initializeEdgeBundlesPass(PassRegistry&);
 void initializeEHContGuardCatchretPass(PassRegistry &);
 void initializeEliminateAvailableExternallyLegacyPassPass(PassRegistry&);
+void initializeExpandLargeFpConvertLegacyPassPass(PassRegistry&);
 void initializeExpandLargeDivRemLegacyPassPass(PassRegistry&);
 void initializeExpandMemCmpPassPass(PassRegistry&);
 void initializeExpandPostRAPass(PassRegistry&);
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -54,6 +54,7 @@
   EHContGuardCatchret.cpp
   ExecutionDomainFix.cpp
   ExpandLargeDivRem.cpp
+  ExpandLargeFpConvert.cpp
   ExpandMemCmp.cpp
   ExpandPostRAPseudos.cpp
   ExpandReductions.cpp
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -37,6 +37,7 @@
   initializeEarlyMachineLICMPass(Registry);
   initializeEarlyTailDuplicatePass(Registry);
   initializeExpandLargeDivRemLegacyPassPass(Registry);
+  initializeExpandLargeFpConvertLegacyPassPass(Registry);
   initializeExpandMemCmpPassPass(Registry);
   initializeExpandPostRAPass(Registry);
   initializeFEntryInserterPass(Registry);
diff --git a/llvm/lib/CodeGen/ExpandLargeFpConvert.cpp b/llvm/lib/CodeGen/ExpandLargeFpConvert.cpp
new file mode 100644
--- /dev/null
+++ b/llvm/lib/CodeGen/ExpandLargeFpConvert.cpp
@@ -0,0 +1,662 @@
+//===--- ExpandLargeFpConvert.cpp - Expand large fp convert----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+
+// This pass expands ‘fptoui .. to’, ‘fptosi .. to’, ‘uitofp .. to’,
+// ‘sitofp .. to’ instructions with a bitwidth above a threshold into
+// auto-generated functions. This is useful for targets like x86_64 that cannot
+// lower fp convertions with more than 128 bits.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/TargetLowering.h"
+#include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+static cl::opt<unsigned>
+    ExpandFpConvertBits("expand-fp-convert-bits", cl::Hidden,
+                     cl::init(llvm::IntegerType::MAX_INT_BITS),
+                     cl::desc("fp convert instructions on integers with "
+                              "more than <N> bits are expanded."));
+
+/// Generate code to convert a fp number to integer, replacing FPToS(U)I with
+/// the generated code. This currently generates code similarly to compiler-rt's
+/// implementations.
+///
+/// An example IR generated from compiler-rt/fixsfdi.c looks like below:
+/// define dso_local i64 @foo(float noundef %a) local_unnamed_addr #0 {
+/// entry:
+///   %0 = bitcast float %a to i32
+///   %conv.i = zext i32 %0 to i64
+///   %tobool.not = icmp sgt i32 %0, -1
+///   %conv = select i1 %tobool.not, i64 1, i64 -1
+///   %and = lshr i64 %conv.i, 23
+///   %shr = and i64 %and, 255
+///   %and2 = and i64 %conv.i, 8388607
+///   %or = or i64 %and2, 8388608
+///   %cmp = icmp ult i64 %shr, 127
+///   br i1 %cmp, label %cleanup, label %if.end
+///
+/// if.end:                                           ; preds = %entry
+///   %sub = add nuw nsw i64 %shr, 4294967169
+///   %conv5 = and i64 %sub, 4294967232
+///   %cmp6.not = icmp eq i64 %conv5, 0
+///   br i1 %cmp6.not, label %if.end12, label %if.then8
+///
+/// if.then8:                                         ; preds = %if.end
+///   %cond11 = select i1 %tobool.not, i64 9223372036854775807, i64 -9223372036854775808
+///   br label %cleanup
+///
+/// if.end12:                                         ; preds = %if.end
+///   %cmp13 = icmp ult i64 %shr, 150
+///   br i1 %cmp13, label %if.then15, label %if.else
+///
+/// if.then15:                                        ; preds = %if.end12
+///   %sub16 = sub nuw nsw i64 150, %shr
+///   %shr17 = lshr i64 %or, %sub16
+///   %mul = mul nsw i64 %shr17, %conv
+///   br label %cleanup
+///
+/// if.else:                                          ; preds = %if.end12
+///   %sub18 = add nsw i64 %shr, -150
+///   %shl = shl i64 %or, %sub18
+///   %mul19 = mul nsw i64 %shl, %conv
+///   br label %cleanup
+///
+/// cleanup:                                          ; preds = %entry, %if.else, %if.then15, %if.then8
+///   %retval.0 = phi i64 [ %cond11, %if.then8 ], [ %mul, %if.then15 ], [ %mul19, %if.else ], [ 0, %entry ]
+///   ret i64 %retval.0
+/// }
+///
+/// Replace fp to integer with generated code.
+static void expandFPToI(Instruction *FPToI) {
+  IRBuilder<> Builder(FPToI);
+  auto *FloatVal = FPToI->getOperand(0);
+  IntegerType *IntTy = cast<IntegerType>(FPToI->getType());
+
+  unsigned BitWidth = FPToI->getType()->getIntegerBitWidth();
+  unsigned FPMantissaWidth = FloatVal->getType()->getFPMantissaWidth() - 1;
+
+  // FIXME: fp16's range is covered by i32. So `fptoi half` can convert
+  // to i32 first following a sext/zext to target integer type.
+  Value *A1 = nullptr;
+  if (FloatVal->getType()->isHalfTy()) {
+    if (FPToI->getOpcode() == Instruction::FPToUI) {
+      Value *A0 = Builder.CreateFPToUI(FloatVal, Builder.getIntNTy(32));
+      A1 = Builder.CreateZExt(A0, IntTy);
+    } else { // FPToSI
+      Value *A0 = Builder.CreateFPToSI(FloatVal, Builder.getIntNTy(32));
+      A1 = Builder.CreateSExt(A0, IntTy);
+    }
+    FPToI->replaceAllUsesWith(A1);
+    FPToI->dropAllReferences();
+    FPToI->eraseFromParent();
+    return;
+  }
+
+  // fp80 conversion is implemented by fpext to fp128 first then do the
+  // conversion.
+  FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
+  unsigned FloatWidth = PowerOf2Ceil(FPMantissaWidth);
+  unsigned ExponentWidth = FloatWidth - FPMantissaWidth - 1;
+  unsigned ExponentBias = (1 << (ExponentWidth - 1)) - 1;
+  Value *ImplicitBit = Builder.CreateShl(
+      Builder.getIntN(BitWidth, 1), Builder.getIntN(BitWidth, FPMantissaWidth));
+  Value *SignificandMask =
+      Builder.CreateSub(ImplicitBit, Builder.getIntN(BitWidth, 1));
+  Value *NegOne = Builder.CreateSExt(
+      ConstantInt::getSigned(Builder.getInt32Ty(), -1), IntTy);
+  Value *NegInf =
+      Builder.CreateShl(ConstantInt::getSigned(IntTy, 1),
+                        ConstantInt::getSigned(IntTy, BitWidth - 1));
+
+  BasicBlock *Entry = Builder.GetInsertBlock();
+  Function *F = Entry->getParent();
+  Entry->setName(Twine(Entry->getName(), "fp-to-i-entry"));
+  BasicBlock *End =
+      Entry->splitBasicBlock(Builder.GetInsertPoint(), "fp-to-i-cleanup");
+  BasicBlock *IfEnd =
+      BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end", F, End);
+  BasicBlock *IfThen5 =
+      BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then5", F, End);
+  BasicBlock *IfEnd9 =
+      BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end9", F, End);
+  BasicBlock *IfThen12 =
+      BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then12", F, End);
+  BasicBlock *IfElse =
+      BasicBlock::Create(Builder.getContext(), "fp-to-i-if-else", F, End);
+
+  Entry->getTerminator()->eraseFromParent();
+
+  // entry:
+  Builder.SetInsertPoint(Entry);
+  Value *FloatVal0 = FloatVal;
+  // fp80 conversion is implemented by fpext to fp128 first then do the
+  // conversion.
+  if (FloatVal->getType()->isX86_FP80Ty())
+    FloatVal0 =
+        Builder.CreateFPExt(FloatVal, Type::getFP128Ty(Builder.getContext()));
+  Value *ARep0 =
+      Builder.CreateBitCast(FloatVal0, Builder.getIntNTy(FloatWidth));
+  Value *ARep = Builder.CreateZExt(ARep0, FPToI->getType());
+  Value *PosOrNeg = Builder.CreateICmpSGT(
+      ARep0, ConstantInt::getSigned(Builder.getIntNTy(FloatWidth), -1));
+  Value *Sign = Builder.CreateSelect(PosOrNeg, ConstantInt::getSigned(IntTy, 1),
+                                     ConstantInt::getSigned(IntTy, -1));
+  Value *And =
+      Builder.CreateLShr(ARep, Builder.getIntN(BitWidth, FPMantissaWidth));
+  Value *And2 = Builder.CreateAnd(
+      And, Builder.getIntN(BitWidth, (1 << ExponentWidth) - 1));
+  Value *Abs = Builder.CreateAnd(ARep, SignificandMask);
+  Value *Or = Builder.CreateOr(Abs, ImplicitBit);
+  Value *Cmp =
+      Builder.CreateICmpULT(And2, Builder.getIntN(BitWidth, ExponentBias));
+  Builder.CreateCondBr(Cmp, End, IfEnd);
+
+  // if.end:
+  Builder.SetInsertPoint(IfEnd);
+  Value *Add1 = Builder.CreateAdd(
+      And2, ConstantInt::getSigned(IntTy, -int64_t(ExponentBias + BitWidth)));
+  Value *Cmp3 =
+      Builder.CreateICmpULT(Add1, ConstantInt::getSigned(IntTy, -BitWidth));
+  Builder.CreateCondBr(Cmp3, IfThen5, IfEnd9);
+
+  // if.then5:
+  Builder.SetInsertPoint(IfThen5);
+  Value *PosInf = Builder.CreateXor(NegOne, NegInf);
+  Value *Cond8 = Builder.CreateSelect(PosOrNeg, PosInf, NegInf);
+  Builder.CreateBr(End);
+
+  // if.end9:
+  Builder.SetInsertPoint(IfEnd9);
+  Value *Cmp10 = Builder.CreateICmpULT(
+      And2, Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth));
+  Builder.CreateCondBr(Cmp10, IfThen12, IfElse);
+
+  // if.then12:
+  Builder.SetInsertPoint(IfThen12);
+  Value *Sub13 = Builder.CreateSub(
+      Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth), And2);
+  Value *Shr14 = Builder.CreateLShr(Or, Sub13);
+  Value *Mul = Builder.CreateMul(Shr14, Sign);
+  Builder.CreateBr(End);
+
+  // if.else:
+  Builder.SetInsertPoint(IfElse);
+  Value *Sub15 = Builder.CreateAdd(
+      And2,
+      ConstantInt::getSigned(IntTy, -(ExponentBias + FPMantissaWidth)));
+  Value *Shl = Builder.CreateShl(Or, Sub15);
+  Value *Mul16 = Builder.CreateMul(Shl, Sign);
+  Builder.CreateBr(End);
+
+  // cleanup:
+  Builder.SetInsertPoint(End, End->begin());
+  PHINode *Retval0 = Builder.CreatePHI(FPToI->getType(), 4);
+
+  Retval0->addIncoming(Cond8, IfThen5);
+  Retval0->addIncoming(Mul, IfThen12);
+  Retval0->addIncoming(Mul16, IfElse);
+  Retval0->addIncoming(Builder.getIntN(BitWidth, 0), Entry);
+
+  FPToI->replaceAllUsesWith(Retval0);
+  FPToI->dropAllReferences();
+  FPToI->eraseFromParent();
+}
+
+/// Generate code to convert a fp number to integer, replacing S(U)IToFP with
+/// the generated code. This currently generates code similarly to compiler-rt's
+/// implementations. This implementation has an implicit assumption that integer
+/// width is larger than fp.
+///
+/// An example IR generated from compiler-rt/floatdisf.c looks like below:
+/// define dso_local float @__floatdisf(i64 noundef %a) local_unnamed_addr #0 {
+/// entry:
+///   %cmp = icmp eq i64 %a, 0
+///   br i1 %cmp, label %return, label %if.end
+///
+/// if.end:                                           ; preds = %entry
+///   %shr = ashr i64 %a, 63
+///   %xor = xor i64 %shr, %a
+///   %sub = sub nsw i64 %xor, %shr
+///   %0 = tail call i64 @llvm.ctlz.i64(i64 %sub, i1 true), !range !5
+///   %cast = trunc i64 %0 to i32
+///   %sub1 = sub nuw nsw i32 64, %cast
+///   %sub2 = xor i32 %cast, 63
+///   %cmp3 = icmp ult i32 %cast, 40
+///   br i1 %cmp3, label %if.then4, label %if.else
+///
+/// if.then4:                                         ; preds = %if.end
+///   switch i32 %sub1, label %sw.default [
+///     i32 25, label %sw.bb
+///     i32 26, label %sw.epilog
+///   ]
+///
+/// sw.bb:                                            ; preds = %if.then4
+///   %shl = shl i64 %sub, 1
+///   br label %sw.epilog
+///
+/// sw.default:                                       ; preds = %if.then4
+///   %sub5 = sub nsw i64 38, %0
+///   %sh_prom = and i64 %sub5, 4294967295
+///   %shr6 = lshr i64 %sub, %sh_prom
+///   %shr9 = lshr i64 274877906943, %0
+///   %and = and i64 %shr9, %sub
+///   %cmp10 = icmp ne i64 %and, 0
+///   %conv11 = zext i1 %cmp10 to i64
+///   %or = or i64 %shr6, %conv11
+///   br label %sw.epilog
+///
+/// sw.epilog:                                        ; preds = %sw.default, %if.then4, %sw.bb
+///   %a.addr.0 = phi i64 [ %or, %sw.default ], [ %sub, %if.then4 ], [ %shl, %sw.bb ]
+///   %1 = lshr i64 %a.addr.0, 2
+///   %2 = and i64 %1, 1
+///   %or16 = or i64 %2, %a.addr.0
+///   %inc = add nsw i64 %or16, 1
+///   %3 = and i64 %inc, 67108864
+///   %tobool.not = icmp eq i64 %3, 0
+///   %spec.select.v = select i1 %tobool.not, i64 2, i64 3
+///   %spec.select = ashr i64 %inc, %spec.select.v
+///   %spec.select56 = select i1 %tobool.not, i32 %sub2, i32 %sub1
+///   br label %if.end26
+///
+/// if.else:                                          ; preds = %if.end
+///   %sub23 = add nuw nsw i64 %0, 4294967256
+///   %sh_prom24 = and i64 %sub23, 4294967295
+///   %shl25 = shl i64 %sub, %sh_prom24
+///   br label %if.end26
+///
+/// if.end26:                                         ; preds = %sw.epilog, %if.else
+///   %a.addr.1 = phi i64 [ %shl25, %if.else ], [ %spec.select, %sw.epilog ]
+///   %e.0 = phi i32 [ %sub2, %if.else ], [ %spec.select56, %sw.epilog ]
+///   %conv27 = trunc i64 %shr to i32
+///   %and28 = and i32 %conv27, -2147483648
+///   %add = shl nuw nsw i32 %e.0, 23
+///   %shl29 = add nuw nsw i32 %add, 1065353216
+///   %conv31 = trunc i64 %a.addr.1 to i32
+///   %and32 = and i32 %conv31, 8388607
+///   %or30 = or i32 %and32, %and28
+///   %or33 = or i32 %or30, %shl29
+///   %4 = bitcast i32 %or33 to float
+///   br label %return
+///
+/// return:                                           ; preds = %entry, %if.end26
+///   %retval.0 = phi float [ %4, %if.end26 ], [ 0.000000e+00, %entry ]
+///   ret float %retval.0
+/// }
+///
+/// Replace integer to fp with generated code.
+static void expandIToFP(Instruction *IToFP) {
+  IRBuilder<> Builder(IToFP);
+  auto *IntVal = IToFP->getOperand(0);
+  IntegerType *IntTy = cast<IntegerType>(IntVal->getType());
+
+  unsigned BitWidth = IntVal->getType()->getIntegerBitWidth();
+  unsigned FPMantissaWidth = IToFP->getType()->getFPMantissaWidth() - 1;
+  // fp80 conversion is implemented by conversion tp fp128 first following
+  // a fptrunc to fp80.
+  FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
+  // FIXME: As there is no related builtins added in compliler-rt,
+  // here currently utilized the fp32 <-> fp16 lib calls to implement.
+  FPMantissaWidth = FPMantissaWidth == 10 ? 23 : FPMantissaWidth;
+  unsigned FloatWidth = PowerOf2Ceil(FPMantissaWidth);
+  bool IsSigned = IToFP->getOpcode() == Instruction::SIToFP;
+
+  assert(BitWidth > FloatWidth && "Unexpected conversion. expandIToFP() "
+                                  "assumes integer width is larger than fp.");
+
+  Value *Temp1 =
+      Builder.CreateShl(Builder.getIntN(BitWidth, 1),
+                        Builder.getIntN(BitWidth, FPMantissaWidth + 3));
+
+  BasicBlock *Entry = Builder.GetInsertBlock();
+  Function *F = Entry->getParent();
+  Entry->setName(Twine(Entry->getName(), "itofp-entry"));
+  BasicBlock *End =
+      Entry->splitBasicBlock(Builder.GetInsertPoint(), "itofp-return");
+  BasicBlock *IfEnd =
+      BasicBlock::Create(Builder.getContext(), "itofp-if-end", F, End);
+  BasicBlock *IfThen4 =
+      BasicBlock::Create(Builder.getContext(), "itofp-if-then4", F, End);
+  BasicBlock *SwBB =
+      BasicBlock::Create(Builder.getContext(), "itofp-sw-bb", F, End);
+  BasicBlock *SwDefault =
+      BasicBlock::Create(Builder.getContext(), "itofp-sw-default", F, End);
+  BasicBlock *SwEpilog =
+      BasicBlock::Create(Builder.getContext(), "itofp-sw-epilog", F, End);
+  BasicBlock *IfThen20 =
+      BasicBlock::Create(Builder.getContext(), "itofp-if-then20", F, End);
+  BasicBlock *IfElse =
+      BasicBlock::Create(Builder.getContext(), "itofp-if-else", F, End);
+  BasicBlock *IfEnd26 =
+      BasicBlock::Create(Builder.getContext(), "itofp-if-end26", F, End);
+
+  Entry->getTerminator()->eraseFromParent();
+
+  Function *CTLZ =
+      Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz, IntTy);
+  ConstantInt *True = Builder.getTrue();
+
+  // entry:
+  Builder.SetInsertPoint(Entry);
+  Value *Cmp = Builder.CreateICmpEQ(IntVal, ConstantInt::getSigned(IntTy, 0));
+  Builder.CreateCondBr(Cmp, End, IfEnd);
+
+  // if.end:
+  Builder.SetInsertPoint(IfEnd);
+  Value *Shr =
+      Builder.CreateAShr(IntVal, Builder.getIntN(BitWidth, BitWidth - 1));
+  Value *Xor = Builder.CreateXor(Shr, IntVal);
+  Value *Sub = Builder.CreateSub(Xor, Shr);
+  Value *Call = Builder.CreateCall(CTLZ, {IsSigned ? Sub : IntVal, True});
+  Value *Cast = Builder.CreateTrunc(Call, Builder.getInt32Ty());
+  int BitWidthNew = FloatWidth == 128 ? BitWidth : 32;
+  Value *Sub1 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth),
+                                  FloatWidth == 128 ? Call : Cast);
+  Value *Sub2 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth - 1),
+                                  FloatWidth == 128 ? Call : Cast);
+  Value *Cmp3 = Builder.CreateICmpSGT(
+      Sub2, Builder.getIntN(BitWidthNew, FPMantissaWidth + 1));
+  Builder.CreateCondBr(Cmp3, IfThen4, IfElse);
+
+  // if.then4:
+  Builder.SetInsertPoint(IfThen4);
+  llvm::SwitchInst *SI = Builder.CreateSwitch(Sub1, SwDefault);
+  SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 2), SwBB);
+  SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 3), SwEpilog);
+
+  // sw.bb:
+  Builder.SetInsertPoint(SwBB);
+  Value *Shl =
+      Builder.CreateShl(IsSigned ? Sub : IntVal, Builder.getIntN(BitWidth, 1));
+  Builder.CreateBr(SwEpilog);
+
+  // sw.default:
+  Builder.SetInsertPoint(SwDefault);
+  Value *Sub5 = Builder.CreateSub(
+      Builder.getIntN(BitWidthNew, BitWidth - FPMantissaWidth - 3),
+      FloatWidth == 128 ? Call : Cast);
+  Value *ShProm = Builder.CreateZExt(Sub5, IntTy);
+  Value *Shr6 = Builder.CreateLShr(IsSigned ? Sub : IntVal,
+                                   FloatWidth == 128 ? Sub5 : ShProm);
+  Value *Sub8 =
+      Builder.CreateAdd(FloatWidth == 128 ? Call : Cast,
+                        Builder.getIntN(BitWidthNew, FPMantissaWidth + 3));
+  Value *ShProm9 = Builder.CreateZExt(Sub8, IntTy);
+  Value *Shr9 = Builder.CreateLShr(ConstantInt::getSigned(IntTy, -1),
+                                   FloatWidth == 128 ? Sub8 : ShProm9);
+  Value *And = Builder.CreateAnd(Shr9, IsSigned ? Sub : IntVal);
+  Value *Cmp10 = Builder.CreateICmpNE(And, Builder.getIntN(BitWidth, 0));
+  Value *Conv11 = Builder.CreateZExt(Cmp10, IntTy);
+  Value *Or = Builder.CreateOr(Shr6, Conv11);
+  Builder.CreateBr(SwEpilog);
+
+  // sw.epilog:
+  Builder.SetInsertPoint(SwEpilog);
+  PHINode *AAddr0 = Builder.CreatePHI(IntTy, 3);
+  AAddr0->addIncoming(Or, SwDefault);
+  AAddr0->addIncoming(IsSigned ? Sub : IntVal, IfThen4);
+  AAddr0->addIncoming(Shl, SwBB);
+  Value *A0 = Builder.CreateTrunc(AAddr0, Builder.getInt32Ty());
+  Value *A1 = Builder.CreateLShr(A0, Builder.getIntN(32, 2));
+  Value *A2 = Builder.CreateAnd(A1, Builder.getIntN(32, 1));
+  Value *Conv16 = Builder.CreateZExt(A2, IntTy);
+  Value *Or17 = Builder.CreateOr(AAddr0, Conv16);
+  Value *Inc = Builder.CreateAdd(Or17, Builder.getIntN(BitWidth, 1));
+  Value *Shr18 = nullptr;
+  if (IsSigned)
+    Shr18 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 2));
+  else
+    Shr18 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 2));
+  Value *A3 = Builder.CreateAnd(Inc, Temp1, "a3");
+  Value *PosOrNeg = Builder.CreateICmpEQ(A3, Builder.getIntN(BitWidth, 0));
+  Value *ExtractT60 = Builder.CreateTrunc(Shr18, Builder.getIntNTy(FloatWidth));
+  Value *Extract63 = Builder.CreateLShr(Shr18, Builder.getIntN(BitWidth, 32));
+  Value *ExtractT64 = nullptr;
+  if (FloatWidth > 80)
+    ExtractT64 = Builder.CreateTrunc(Sub2, Builder.getInt64Ty());
+  else
+    ExtractT64 = Builder.CreateTrunc(Extract63, Builder.getInt32Ty());
+  Builder.CreateCondBr(PosOrNeg, IfEnd26, IfThen20);
+
+  // if.then20
+  Builder.SetInsertPoint(IfThen20);
+  Value *Shr21 = nullptr;
+  if (IsSigned)
+    Shr21 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 3));
+  else
+    Shr21 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 3));
+  Value *ExtractT = Builder.CreateTrunc(Shr21, Builder.getIntNTy(FloatWidth));
+  Value *Extract = Builder.CreateLShr(Shr21, Builder.getIntN(BitWidth, 32));
+  Value *ExtractT62 = nullptr;
+  if (FloatWidth > 80)
+    ExtractT62 = Builder.CreateTrunc(Sub1, Builder.getIntNTy(64));
+  else
+    ExtractT62 = Builder.CreateTrunc(Extract, Builder.getIntNTy(32));
+  Builder.CreateBr(IfEnd26);
+
+  // if.else:
+  Builder.SetInsertPoint(IfElse);
+  Value *Sub24 = Builder.CreateAdd(
+      FloatWidth == 128 ? Call : Cast,
+      ConstantInt::getSigned(Builder.getIntNTy(BitWidthNew),
+                             -(BitWidth - FPMantissaWidth - 1)));
+  Value *ShProm25 = Builder.CreateZExt(Sub24, IntTy);
+  Value *Shl26 = Builder.CreateShl(IsSigned ? Sub : IntVal,
+                                   FloatWidth == 128 ? Sub24 : ShProm25);
+  Value *ExtractT61 = Builder.CreateTrunc(Shl26, Builder.getIntNTy(FloatWidth));
+  Value *Extract65 = Builder.CreateLShr(Shl26, Builder.getIntN(BitWidth, 32));
+  Value *ExtractT66 = nullptr;
+  if (FloatWidth > 80)
+    ExtractT66 = Builder.CreateTrunc(Sub2, Builder.getIntNTy(64));
+  else
+    ExtractT66 = Builder.CreateTrunc(Extract65, Builder.getInt32Ty());
+  Builder.CreateBr(IfEnd26);
+
+  // if.end26:
+  Builder.SetInsertPoint(IfEnd26);
+  PHINode *AAddr1Off0 = Builder.CreatePHI(Builder.getIntNTy(FloatWidth), 3);
+  AAddr1Off0->addIncoming(ExtractT, IfThen20);
+  AAddr1Off0->addIncoming(ExtractT60, SwEpilog);
+  AAddr1Off0->addIncoming(ExtractT61, IfElse);
+  PHINode *AAddr1Off32 = nullptr;
+  if (FloatWidth > 32) {
+    AAddr1Off32 =
+        Builder.CreatePHI(Builder.getIntNTy(FloatWidth > 80 ? 64 : 32), 3);
+    AAddr1Off32->addIncoming(ExtractT62, IfThen20);
+    AAddr1Off32->addIncoming(ExtractT64, SwEpilog);
+    AAddr1Off32->addIncoming(ExtractT66, IfElse);
+  }
+  PHINode *E0 = nullptr;
+  if (FloatWidth <= 80) {
+    E0 = Builder.CreatePHI(Builder.getIntNTy(BitWidthNew), 3);
+    E0->addIncoming(Sub1, IfThen20);
+    E0->addIncoming(Sub2, SwEpilog);
+    E0->addIncoming(Sub2, IfElse);
+  }
+  Value *And29 = nullptr;
+  if (FloatWidth > 80) {
+    Value *Temp2 = Builder.CreateShl(Builder.getIntN(BitWidth, 1),
+                                     Builder.getIntN(BitWidth, 63));
+    And29 = Builder.CreateAnd(Shr, Temp2, "and29");
+  } else {
+    Value *Conv28 = Builder.CreateTrunc(Shr, Builder.getIntNTy(32));
+    And29 = Builder.CreateAnd(
+        Conv28, ConstantInt::getSigned(Builder.getIntNTy(32), 0x80000000));
+  }
+  unsigned TempMod = FPMantissaWidth % 32;
+  Value *And34 = nullptr;
+  Value *Shl30 = nullptr;
+  if (FloatWidth > 80) {
+    TempMod += 32;
+    Value *Add = Builder.CreateShl(AAddr1Off32, Builder.getIntN(64, TempMod));
+    Shl30 = Builder.CreateAdd(
+        Add,
+        Builder.getIntN(64, ((1ull << (62ull - TempMod)) - 1ull) << TempMod));
+    And34 = Builder.CreateZExt(Shl30, Builder.getIntNTy(128));
+  } else {
+    Value *Add = Builder.CreateShl(E0, Builder.getIntN(32, TempMod));
+    Shl30 = Builder.CreateAdd(
+        Add, Builder.getIntN(32, ((1 << (30 - TempMod)) - 1) << TempMod));
+    And34 = Builder.CreateAnd(FloatWidth > 32 ? AAddr1Off32 : AAddr1Off0,
+                              Builder.getIntN(32, (1 << TempMod) - 1));
+  }
+  Value *Or35 = nullptr;
+  if (FloatWidth > 80) {
+    Value *And29Trunc = Builder.CreateTrunc(And29, Builder.getIntNTy(128));
+    Value *Or31 = Builder.CreateOr(And29Trunc, And34);
+    Value *Or34 = Builder.CreateShl(Or31, Builder.getIntN(128, 64));
+    Value *Temp3 = Builder.CreateShl(Builder.getIntN(128, 1),
+                                     Builder.getIntN(128, FPMantissaWidth));
+    Value *Temp4 = Builder.CreateSub(Temp3, Builder.getIntN(128, 1));
+    Value *A6 = Builder.CreateAnd(AAddr1Off0, Temp4);
+    Or35 = Builder.CreateOr(Or34, A6);
+  } else {
+    Value *Or31 = Builder.CreateOr(And34, And29);
+    Or35 = Builder.CreateOr(IsSigned ? Or31 : And34, Shl30);
+  }
+  Value *A4 = nullptr;
+  if (IToFP->getType()->isDoubleTy()) {
+    Value *ZExt1 = Builder.CreateZExt(Or35, Builder.getIntNTy(FloatWidth));
+    Value *Shl1 = Builder.CreateShl(ZExt1, Builder.getIntN(FloatWidth, 32));
+    Value *And1 =
+        Builder.CreateAnd(AAddr1Off0, Builder.getIntN(FloatWidth, 0xFFFFFFFF));
+    Value *Or1 = Builder.CreateOr(Shl1, And1);
+    A4 = Builder.CreateBitCast(Or1, IToFP->getType());
+  } else if (IToFP->getType()->isX86_FP80Ty()) {
+    Value *A40 =
+        Builder.CreateBitCast(Or35, Type::getFP128Ty(Builder.getContext()));
+    A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
+  } else if (IToFP->getType()->isHalfTy()) {
+    // Deal with "half" situation. This is a workaround since we don't have
+    // floattihf.c currently as referring.
+    Value *A40 =
+        Builder.CreateBitCast(Or35, Type::getFloatTy(Builder.getContext()));
+    A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
+  } else // float type
+    A4 = Builder.CreateBitCast(Or35, IToFP->getType());
+  Builder.CreateBr(End);
+
+  // return:
+  Builder.SetInsertPoint(End, End->begin());
+  PHINode *Retval0 = Builder.CreatePHI(IToFP->getType(), 2);
+  Retval0->addIncoming(A4, IfEnd26);
+  Retval0->addIncoming(ConstantFP::getZero(IToFP->getType(), false), Entry);
+
+  IToFP->replaceAllUsesWith(Retval0);
+  IToFP->dropAllReferences();
+  IToFP->eraseFromParent();
+}
+
+static bool runImpl(Function &F, const TargetLowering &TLI) {
+  SmallVector<Instruction *, 4> Replace;
+  bool Modified = false;
+
+  unsigned MaxLegalFpConvertBitWidth =
+      TLI.getMaxLargeFPConvertBitWidthSupported();
+  if (ExpandFpConvertBits != llvm::IntegerType::MAX_INT_BITS)
+    MaxLegalFpConvertBitWidth = ExpandFpConvertBits;
+
+  if (MaxLegalFpConvertBitWidth >= llvm::IntegerType::MAX_INT_BITS)
+    return false;
+
+  for (auto &I : instructions(F)) {
+    switch (I.getOpcode()) {
+    case Instruction::FPToUI:
+    case Instruction::FPToSI: {
+      // TODO: This pass doesn't handle vectors.
+      if (I.getOperand(0)->getType()->isVectorTy())
+        continue;
+
+      auto *IntTy = dyn_cast<IntegerType>(I.getType());
+      if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
+        continue;
+
+      Replace.push_back(&I);
+      Modified = true;
+      break;
+    }
+    case Instruction::UIToFP:
+    case Instruction::SIToFP: {
+      // TODO: This pass doesn't handle vectors.
+      if (I.getOperand(0)->getType()->isVectorTy())
+        continue;
+
+      auto *IntTy = dyn_cast<IntegerType>(I.getOperand(0)->getType());
+      if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
+        continue;
+
+      Replace.push_back(&I);
+      Modified = true;
+      break;
+    }
+    default:
+      break;
+    }
+  }
+
+  if (Replace.empty())
+    return false;
+
+  while (!Replace.empty()) {
+    Instruction *I = Replace.pop_back_val();
+    if (I->getOpcode() == Instruction::FPToUI ||
+        I->getOpcode() == Instruction::FPToSI) {
+      expandFPToI(I);
+    } else {
+      expandIToFP(I);
+    }
+  }
+
+  return Modified;
+}
+
+class ExpandLargeFpConvertLegacyPass : public FunctionPass {
+public:
+  static char ID;
+
+  ExpandLargeFpConvertLegacyPass() : FunctionPass(ID) {
+    initializeExpandLargeFpConvertLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+
+  bool runOnFunction(Function &F) override {
+    auto *TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
+    auto *TLI = TM->getSubtargetImpl(F)->getTargetLowering();
+    return runImpl(F, *TLI);
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<TargetPassConfig>();
+    AU.addPreserved<AAResultsWrapperPass>();
+    AU.addPreserved<GlobalsAAWrapperPass>();
+  }
+};
+
+char ExpandLargeFpConvertLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
+                      "Expand large fp convert", false, false)
+INITIALIZE_PASS_END(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
+                    "Expand large fp convert", false, false)
+
+FunctionPass *llvm::createExpandLargeFpConvertPass() {
+  return new ExpandLargeFpConvertLegacyPass();
+}
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -726,6 +726,8 @@
 
   MaxDivRemBitWidthSupported = llvm::IntegerType::MAX_INT_BITS;
 
+  MaxLargeFPConvertBitWidthSupported = llvm::IntegerType::MAX_INT_BITS;
+
   MinCmpXchgSizeInBits = 0;
   SupportsUnalignedAtomics = false;
 
diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -1114,6 +1114,7 @@
   addPass(createPreISelIntrinsicLoweringPass());
   PM->add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
   addPass(createExpandLargeDivRemPass());
+  addPass(createExpandLargeFpConvertPass());
   addIRPasses();
   addCodeGenPrepare();
   addPassesToHandleExceptions();
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -172,6 +172,8 @@
 
   setMaxDivRemBitWidthSupported(Subtarget.is64Bit() ? 128 : 64);
 
+  setMaxLargeFPConvertBitWidthSupported(128);
+
   // Set up the register classes.
   addRegisterClass(MVT::i8, &X86::GR8RegClass);
   addRegisterClass(MVT::i16, &X86::GR16RegClass);
diff --git a/llvm/test/CodeGen/AArch64/O0-pipeline.ll b/llvm/test/CodeGen/AArch64/O0-pipeline.ll
--- a/llvm/test/CodeGen/AArch64/O0-pipeline.ll
+++ b/llvm/test/CodeGen/AArch64/O0-pipeline.ll
@@ -16,6 +16,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:       Module Verifier
 ; CHECK-NEXT:       Lower Garbage Collection Instructions
diff --git a/llvm/test/CodeGen/AArch64/O3-pipeline.ll b/llvm/test/CodeGen/AArch64/O3-pipeline.ll
--- a/llvm/test/CodeGen/AArch64/O3-pipeline.ll
+++ b/llvm/test/CodeGen/AArch64/O3-pipeline.ll
@@ -20,6 +20,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:     SVE intrinsics optimizations
 ; CHECK-NEXT:       FunctionPass Manager
diff --git a/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll b/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
--- a/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
+++ b/llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
@@ -28,6 +28,7 @@
 ; GCN-O0-NEXT:    Pre-ISel Intrinsic Lowering
 ; GCN-O0-NEXT:    FunctionPass Manager
 ; GCN-O0-NEXT:      Expand large div/rem
+; GCN-O0-NEXT:      Expand large fp convert
 ; GCN-O0-NEXT:    AMDGPU Printf lowering
 ; GCN-O0-NEXT:      FunctionPass Manager
 ; GCN-O0-NEXT:        Dominator Tree Construction
@@ -169,6 +170,7 @@
 ; GCN-O1-NEXT:    Pre-ISel Intrinsic Lowering
 ; GCN-O1-NEXT:    FunctionPass Manager
 ; GCN-O1-NEXT:      Expand large div/rem
+; GCN-O1-NEXT:      Expand large fp convert
 ; GCN-O1-NEXT:    AMDGPU Printf lowering
 ; GCN-O1-NEXT:      FunctionPass Manager
 ; GCN-O1-NEXT:        Dominator Tree Construction
@@ -432,6 +434,7 @@
 ; GCN-O1-OPTS-NEXT:    Pre-ISel Intrinsic Lowering
 ; GCN-O1-OPTS-NEXT:    FunctionPass Manager
 ; GCN-O1-OPTS-NEXT:      Expand large div/rem
+; GCN-O1-OPTS-NEXT:      Expand large fp convert
 ; GCN-O1-OPTS-NEXT:    AMDGPU Printf lowering
 ; GCN-O1-OPTS-NEXT:      FunctionPass Manager
 ; GCN-O1-OPTS-NEXT:        Dominator Tree Construction
@@ -727,6 +730,7 @@
 ; GCN-O2-NEXT:    Pre-ISel Intrinsic Lowering
 ; GCN-O2-NEXT:    FunctionPass Manager
 ; GCN-O2-NEXT:      Expand large div/rem
+; GCN-O2-NEXT:      Expand large fp convert
 ; GCN-O2-NEXT:    AMDGPU Printf lowering
 ; GCN-O2-NEXT:      FunctionPass Manager
 ; GCN-O2-NEXT:        Dominator Tree Construction
@@ -1025,6 +1029,7 @@
 ; GCN-O3-NEXT:    Pre-ISel Intrinsic Lowering
 ; GCN-O3-NEXT:    FunctionPass Manager
 ; GCN-O3-NEXT:      Expand large div/rem
+; GCN-O3-NEXT:      Expand large fp convert
 ; GCN-O3-NEXT:    AMDGPU Printf lowering
 ; GCN-O3-NEXT:      FunctionPass Manager
 ; GCN-O3-NEXT:        Dominator Tree Construction
diff --git a/llvm/test/CodeGen/ARM/O3-pipeline.ll b/llvm/test/CodeGen/ARM/O3-pipeline.ll
--- a/llvm/test/CodeGen/ARM/O3-pipeline.ll
+++ b/llvm/test/CodeGen/ARM/O3-pipeline.ll
@@ -6,6 +6,7 @@
 ; CHECK-NEXT:    Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:    FunctionPass Manager
 ; CHECK-NEXT:      Expand large div/rem
+; CHECK-NEXT:      Expand large fp convert
 ; CHECK-NEXT:      Expand Atomic instructions
 ; CHECK-NEXT:      Simplify the CFG
 ; CHECK-NEXT:      Dominator Tree Construction
diff --git a/llvm/test/CodeGen/M68k/pipeline.ll b/llvm/test/CodeGen/M68k/pipeline.ll
--- a/llvm/test/CodeGen/M68k/pipeline.ll
+++ b/llvm/test/CodeGen/M68k/pipeline.ll
@@ -3,6 +3,7 @@
 ; CHECK-NEXT:    Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:    FunctionPass Manager
 ; CHECK-NEXT:      Expand large div/rem
+; CHECK-NEXT:      Expand large fp convert
 ; CHECK-NEXT:      Expand Atomic instructions
 ; CHECK-NEXT:      Module Verifier
 ; CHECK-NEXT:      Dominator Tree Construction
diff --git a/llvm/test/CodeGen/PowerPC/O3-pipeline.ll b/llvm/test/CodeGen/PowerPC/O3-pipeline.ll
--- a/llvm/test/CodeGen/PowerPC/O3-pipeline.ll
+++ b/llvm/test/CodeGen/PowerPC/O3-pipeline.ll
@@ -20,6 +20,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Convert i1 constants to i32/i64 if they are returned
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:     PPC Lower MASS Entries
diff --git a/llvm/test/CodeGen/RISCV/O0-pipeline.ll b/llvm/test/CodeGen/RISCV/O0-pipeline.ll
--- a/llvm/test/CodeGen/RISCV/O0-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O0-pipeline.ll
@@ -20,6 +20,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:       Module Verifier
 ; CHECK-NEXT:       Lower Garbage Collection Instructions
diff --git a/llvm/test/CodeGen/RISCV/O3-pipeline.ll b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
--- a/llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -24,6 +24,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:       Dominator Tree Construction
 ; CHECK-NEXT:       Natural Loop Information
diff --git a/llvm/test/CodeGen/X86/O0-pipeline.ll b/llvm/test/CodeGen/X86/O0-pipeline.ll
--- a/llvm/test/CodeGen/X86/O0-pipeline.ll
+++ b/llvm/test/CodeGen/X86/O0-pipeline.ll
@@ -18,6 +18,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:       Lower AMX intrinsics
 ; CHECK-NEXT:       Lower AMX type for load/store
diff --git a/llvm/test/CodeGen/X86/expand-large-fp-convert-fptosi129.ll b/llvm/test/CodeGen/X86/expand-large-fp-convert-fptosi129.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/expand-large-fp-convert-fptosi129.ll
@@ -0,0 +1,177 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -mtriple=x86_64-- -expand-large-fp-convert < %s | FileCheck %s
+
+define i129 @halftosi129(half %a) {
+; CHECK-LABEL: @halftosi129(
+; CHECK-NEXT:    [[TMP1:%.*]] = fptosi half [[A:%.*]] to i32
+; CHECK-NEXT:    [[TMP2:%.*]] = sext i32 [[TMP1]] to i129
+; CHECK-NEXT:    ret i129 [[TMP2]]
+;
+  %conv = fptosi half %a to i129
+  ret i129 %conv
+}
+
+define i129 @floattosi129(float %a) {
+; CHECK-LABEL: @floattosi129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast float [[A:%.*]] to i32
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 23
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 255
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 8388607
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 8388608
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 127
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -256
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 150
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 150, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294967146
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptosi float %a to i129
+  ret i129 %conv
+}
+
+define i129 @doubletosi129(double %a) {
+; CHECK-LABEL: @doubletosi129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double [[A:%.*]] to i64
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i64 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i64 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 52
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 2047
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 4503599627370495
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 4503599627370496
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 1023
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -1152
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 1075
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 1075, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294966221
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptosi double %a to i129
+  ret i129 %conv
+}
+
+define i129 @x86_fp80tosi129(x86_fp80 %a) {
+; CHECK-LABEL: @x86_fp80tosi129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = fpext x86_fp80 [[A:%.*]] to fp128
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast fp128 [[TMP0]] to i128
+; CHECK-NEXT:    [[TMP2:%.*]] = zext i128 [[TMP1]] to i129
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp sgt i128 [[TMP1]], -1
+; CHECK-NEXT:    [[TMP4:%.*]] = select i1 [[TMP3]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP5:%.*]] = lshr i129 [[TMP2]], 112
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP5]], 32767
+; CHECK-NEXT:    [[TMP7:%.*]] = and i129 [[TMP2]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP8:%.*]] = or i129 [[TMP7]], 5192296858534827628530496329220096
+; CHECK-NEXT:    [[TMP9:%.*]] = icmp ult i129 [[TMP6]], 16383
+; CHECK-NEXT:    br i1 [[TMP9]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP10:%.*]] = add i129 [[TMP6]], -16512
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp ult i129 [[TMP10]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP11]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP12:%.*]] = select i1 [[TMP3]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp ult i129 [[TMP6]], 16495
+; CHECK-NEXT:    br i1 [[TMP13]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP14:%.*]] = sub i129 16495, [[TMP6]]
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 [[TMP8]], [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = mul i129 [[TMP15]], [[TMP4]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP17:%.*]] = add i129 [[TMP6]], 4294950801
+; CHECK-NEXT:    [[TMP18:%.*]] = shl i129 [[TMP8]], [[TMP17]]
+; CHECK-NEXT:    [[TMP19:%.*]] = mul i129 [[TMP18]], [[TMP4]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP12]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP16]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP19]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP20]]
+;
+  %conv = fptosi x86_fp80 %a to i129
+  ret i129 %conv
+}
+
+define i129 @fp128tosi129(fp128 %a) {
+; CHECK-LABEL: @fp128tosi129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast fp128 [[A:%.*]] to i128
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i128 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i128 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 112
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 32767
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 5192296858534827628530496329220096
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 16383
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -16512
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 16495
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 16495, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294950801
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptosi fp128 %a to i129
+  ret i129 %conv
+}
diff --git a/llvm/test/CodeGen/X86/expand-large-fp-convert-fptoui129.ll b/llvm/test/CodeGen/X86/expand-large-fp-convert-fptoui129.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/expand-large-fp-convert-fptoui129.ll
@@ -0,0 +1,177 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -mtriple=x86_64-- -expand-large-fp-convert < %s | FileCheck %s
+
+define i129 @halftoui129(half %a) {
+; CHECK-LABEL: @halftoui129(
+; CHECK-NEXT:    [[TMP1:%.*]] = fptoui half [[A:%.*]] to i32
+; CHECK-NEXT:    [[TMP2:%.*]] = zext i32 [[TMP1]] to i129
+; CHECK-NEXT:    ret i129 [[TMP2]]
+;
+  %conv = fptoui half %a to i129
+  ret i129 %conv
+}
+
+define i129 @floattoui129(float %a) {
+; CHECK-LABEL: @floattoui129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast float [[A:%.*]] to i32
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 23
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 255
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 8388607
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 8388608
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 127
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -256
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 150
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 150, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294967146
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptoui float %a to i129
+  ret i129 %conv
+}
+
+define i129 @doubletoui129(double %a) {
+; CHECK-LABEL: @doubletoui129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double [[A:%.*]] to i64
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i64 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i64 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 52
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 2047
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 4503599627370495
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 4503599627370496
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 1023
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -1152
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 1075
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 1075, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294966221
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptoui double %a to i129
+  ret i129 %conv
+}
+
+define i129 @x86_fp80toui129(x86_fp80 %a) {
+; CHECK-LABEL: @x86_fp80toui129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = fpext x86_fp80 [[A:%.*]] to fp128
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast fp128 [[TMP0]] to i128
+; CHECK-NEXT:    [[TMP2:%.*]] = zext i128 [[TMP1]] to i129
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp sgt i128 [[TMP1]], -1
+; CHECK-NEXT:    [[TMP4:%.*]] = select i1 [[TMP3]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP5:%.*]] = lshr i129 [[TMP2]], 112
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP5]], 32767
+; CHECK-NEXT:    [[TMP7:%.*]] = and i129 [[TMP2]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP8:%.*]] = or i129 [[TMP7]], 5192296858534827628530496329220096
+; CHECK-NEXT:    [[TMP9:%.*]] = icmp ult i129 [[TMP6]], 16383
+; CHECK-NEXT:    br i1 [[TMP9]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP10:%.*]] = add i129 [[TMP6]], -16512
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp ult i129 [[TMP10]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP11]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP12:%.*]] = select i1 [[TMP3]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp ult i129 [[TMP6]], 16495
+; CHECK-NEXT:    br i1 [[TMP13]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP14:%.*]] = sub i129 16495, [[TMP6]]
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 [[TMP8]], [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = mul i129 [[TMP15]], [[TMP4]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP17:%.*]] = add i129 [[TMP6]], 4294950801
+; CHECK-NEXT:    [[TMP18:%.*]] = shl i129 [[TMP8]], [[TMP17]]
+; CHECK-NEXT:    [[TMP19:%.*]] = mul i129 [[TMP18]], [[TMP4]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP12]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP16]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP19]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP20]]
+;
+  %conv = fptoui x86_fp80 %a to i129
+  ret i129 %conv
+}
+
+define i129 @fp128toui129(fp128 %a) {
+; CHECK-LABEL: @fp128toui129(
+; CHECK-NEXT:  fp-to-i-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast fp128 [[A:%.*]] to i128
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i128 [[TMP0]] to i129
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i128 [[TMP0]], -1
+; CHECK-NEXT:    [[TMP3:%.*]] = select i1 [[TMP2]], i129 1, i129 -1
+; CHECK-NEXT:    [[TMP4:%.*]] = lshr i129 [[TMP1]], 112
+; CHECK-NEXT:    [[TMP5:%.*]] = and i129 [[TMP4]], 32767
+; CHECK-NEXT:    [[TMP6:%.*]] = and i129 [[TMP1]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP7:%.*]] = or i129 [[TMP6]], 5192296858534827628530496329220096
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ult i129 [[TMP5]], 16383
+; CHECK-NEXT:    br i1 [[TMP8]], label [[FP_TO_I_CLEANUP:%.*]], label [[FP_TO_I_IF_END:%.*]]
+; CHECK:       fp-to-i-if-end:
+; CHECK-NEXT:    [[TMP9:%.*]] = add i129 [[TMP5]], -16512
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ult i129 [[TMP9]], 4294967167
+; CHECK-NEXT:    br i1 [[TMP10]], label [[FP_TO_I_IF_THEN5:%.*]], label [[FP_TO_I_IF_END9:%.*]]
+; CHECK:       fp-to-i-if-then5:
+; CHECK-NEXT:    [[TMP11:%.*]] = select i1 [[TMP2]], i129 340282366920938463463374607431768211455, i129 -340282366920938463463374607431768211456
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-end9:
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult i129 [[TMP5]], 16495
+; CHECK-NEXT:    br i1 [[TMP12]], label [[FP_TO_I_IF_THEN12:%.*]], label [[FP_TO_I_IF_ELSE:%.*]]
+; CHECK:       fp-to-i-if-then12:
+; CHECK-NEXT:    [[TMP13:%.*]] = sub i129 16495, [[TMP5]]
+; CHECK-NEXT:    [[TMP14:%.*]] = lshr i129 [[TMP7]], [[TMP13]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i129 [[TMP14]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-if-else:
+; CHECK-NEXT:    [[TMP16:%.*]] = add i129 [[TMP5]], 4294950801
+; CHECK-NEXT:    [[TMP17:%.*]] = shl i129 [[TMP7]], [[TMP16]]
+; CHECK-NEXT:    [[TMP18:%.*]] = mul i129 [[TMP17]], [[TMP3]]
+; CHECK-NEXT:    br label [[FP_TO_I_CLEANUP]]
+; CHECK:       fp-to-i-cleanup:
+; CHECK-NEXT:    [[TMP19:%.*]] = phi i129 [ [[TMP11]], [[FP_TO_I_IF_THEN5]] ], [ [[TMP15]], [[FP_TO_I_IF_THEN12]] ], [ [[TMP18]], [[FP_TO_I_IF_ELSE]] ], [ 0, [[FP_TO_I_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i129 [[TMP19]]
+;
+  %conv = fptoui fp128 %a to i129
+  ret i129 %conv
+}
diff --git a/llvm/test/CodeGen/X86/expand-large-fp-convert-si129tofp.ll b/llvm/test/CodeGen/X86/expand-large-fp-convert-si129tofp.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/expand-large-fp-convert-si129tofp.ll
@@ -0,0 +1,427 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -mtriple=x86_64-- -expand-large-fp-convert < %s | FileCheck %s
+
+define half @si129tohalf(i129 %a) {
+; CHECK-LABEL: @si129tohalf(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[TMP3]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 24
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 25, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 26, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[TMP3]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 103, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[TMP3]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 26
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[TMP3]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[TMP3]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = ashr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 67108864
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i32
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = ashr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i32
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -105
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[TMP3]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i32
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i32 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP45:%.*]] = and i32 [[TMP44]], -2147483648
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i32 [[TMP43]], 23
+; CHECK-NEXT:    [[TMP47:%.*]] = add i32 [[TMP46]], 1065353216
+; CHECK-NEXT:    [[TMP48:%.*]] = and i32 [[TMP42]], 8388607
+; CHECK-NEXT:    [[TMP49:%.*]] = or i32 [[TMP48]], [[TMP45]]
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP49]], [[TMP47]]
+; CHECK-NEXT:    [[TMP51:%.*]] = bitcast i32 [[TMP50]] to float
+; CHECK-NEXT:    [[TMP52:%.*]] = fptrunc float [[TMP51]] to half
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP53:%.*]] = phi half [ [[TMP52]], [[ITOFP_IF_END26]] ], [ 0xH0000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret half [[TMP53]]
+;
+  %conv = sitofp i129 %a to half
+  ret half %conv
+}
+
+define float @si129tofloat(i129 %a) {
+; CHECK-LABEL: @si129tofloat(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[TMP3]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 24
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 25, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 26, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[TMP3]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 103, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[TMP3]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 26
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[TMP3]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[TMP3]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = ashr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 67108864
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i32
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = ashr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i32
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -105
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[TMP3]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i32
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i32 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP45:%.*]] = and i32 [[TMP44]], -2147483648
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i32 [[TMP43]], 23
+; CHECK-NEXT:    [[TMP47:%.*]] = add i32 [[TMP46]], 1065353216
+; CHECK-NEXT:    [[TMP48:%.*]] = and i32 [[TMP42]], 8388607
+; CHECK-NEXT:    [[TMP49:%.*]] = or i32 [[TMP48]], [[TMP45]]
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP49]], [[TMP47]]
+; CHECK-NEXT:    [[TMP51:%.*]] = bitcast i32 [[TMP50]] to float
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP52:%.*]] = phi float [ [[TMP51]], [[ITOFP_IF_END26]] ], [ 0.000000e+00, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[TMP52]]
+;
+  %conv = sitofp i129 %a to float
+  ret float %conv
+}
+
+define double @si129todouble(i129 %a) {
+; CHECK-LABEL: @si129todouble(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[TMP3]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 53
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 54, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 55, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[TMP3]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 74, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[TMP3]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 55
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[TMP3]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[TMP3]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = ashr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 36028797018963968
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i64
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = ashr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i64
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -76
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[TMP3]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i64
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP35]], [[ITOFP_IF_THEN20]] ], [ [[TMP31]], [[ITOFP_SW_EPILOG]] ], [ [[TMP41]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP45:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP46:%.*]] = and i32 [[TMP45]], -2147483648
+; CHECK-NEXT:    [[TMP47:%.*]] = shl i32 [[TMP44]], 20
+; CHECK-NEXT:    [[TMP48:%.*]] = add i32 [[TMP47]], 1072693248
+; CHECK-NEXT:    [[TMP49:%.*]] = and i32 [[TMP43]], 1048575
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP49]], [[TMP46]]
+; CHECK-NEXT:    [[TMP51:%.*]] = or i32 [[TMP50]], [[TMP48]]
+; CHECK-NEXT:    [[TMP52:%.*]] = zext i32 [[TMP51]] to i64
+; CHECK-NEXT:    [[TMP53:%.*]] = shl i64 [[TMP52]], 32
+; CHECK-NEXT:    [[TMP54:%.*]] = and i64 [[TMP42]], 4294967295
+; CHECK-NEXT:    [[TMP55:%.*]] = or i64 [[TMP53]], [[TMP54]]
+; CHECK-NEXT:    [[TMP56:%.*]] = bitcast i64 [[TMP55]] to double
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP57:%.*]] = phi double [ [[TMP56]], [[ITOFP_IF_END26]] ], [ 0.000000e+00, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret double [[TMP57]]
+;
+  %conv = sitofp i129 %a to double
+  ret double %conv
+}
+
+define x86_fp80 @si129tox86_fp80(i129 %a) {
+; CHECK-LABEL: @si129tox86_fp80(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[TMP3]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i129 129, [[TMP4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i129 128, [[TMP4]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i129 [[TMP7]], 113
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i129 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i129 114, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i129 115, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[TMP3]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i129 14, [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = lshr i129 [[TMP3]], [[TMP10]]
+; CHECK-NEXT:    [[TMP12:%.*]] = add i129 [[TMP4]], 115
+; CHECK-NEXT:    [[TMP13:%.*]] = lshr i129 -1, [[TMP12]]
+; CHECK-NEXT:    [[TMP14:%.*]] = and i129 [[TMP13]], [[TMP3]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp ne i129 [[TMP14]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = zext i1 [[TMP15]] to i129
+; CHECK-NEXT:    [[TMP17:%.*]] = or i129 [[TMP11]], [[TMP16]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP18:%.*]] = phi i129 [ [[TMP17]], [[ITOFP_SW_DEFAULT]] ], [ [[TMP3]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP19:%.*]] = trunc i129 [[TMP18]] to i32
+; CHECK-NEXT:    [[TMP20:%.*]] = lshr i32 [[TMP19]], 2
+; CHECK-NEXT:    [[TMP21:%.*]] = and i32 [[TMP20]], 1
+; CHECK-NEXT:    [[TMP22:%.*]] = zext i32 [[TMP21]] to i129
+; CHECK-NEXT:    [[TMP23:%.*]] = or i129 [[TMP18]], [[TMP22]]
+; CHECK-NEXT:    [[TMP24:%.*]] = add i129 [[TMP23]], 1
+; CHECK-NEXT:    [[TMP25:%.*]] = ashr i129 [[TMP24]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP24]], 41538374868278621028243970633760768
+; CHECK-NEXT:    [[TMP26:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP27:%.*]] = trunc i129 [[TMP25]] to i128
+; CHECK-NEXT:    [[TMP28:%.*]] = lshr i129 [[TMP25]], 32
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br i1 [[TMP26]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP30:%.*]] = ashr i129 [[TMP24]], 3
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i128
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP30]], 32
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP6]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP34:%.*]] = add i129 [[TMP4]], 4294967280
+; CHECK-NEXT:    [[TMP35:%.*]] = shl i129 [[TMP3]], [[TMP34]]
+; CHECK-NEXT:    [[TMP36:%.*]] = trunc i129 [[TMP35]] to i128
+; CHECK-NEXT:    [[TMP37:%.*]] = lshr i129 [[TMP35]], 32
+; CHECK-NEXT:    [[TMP38:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP39:%.*]] = phi i128 [ [[TMP31]], [[ITOFP_IF_THEN20]] ], [ [[TMP27]], [[ITOFP_SW_EPILOG]] ], [ [[TMP36]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP40:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP38]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[AND29:%.*]] = and i129 [[TMP1]], 9223372036854775808
+; CHECK-NEXT:    [[TMP41:%.*]] = shl i64 [[TMP40]], 48
+; CHECK-NEXT:    [[TMP42:%.*]] = add i64 [[TMP41]], 4611404543450677248
+; CHECK-NEXT:    [[TMP43:%.*]] = zext i64 [[TMP42]] to i128
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[AND29]] to i128
+; CHECK-NEXT:    [[TMP45:%.*]] = or i128 [[TMP44]], [[TMP43]]
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i128 [[TMP45]], 64
+; CHECK-NEXT:    [[TMP47:%.*]] = and i128 [[TMP39]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP48:%.*]] = or i128 [[TMP46]], [[TMP47]]
+; CHECK-NEXT:    [[TMP49:%.*]] = bitcast i128 [[TMP48]] to fp128
+; CHECK-NEXT:    [[TMP50:%.*]] = fptrunc fp128 [[TMP49]] to x86_fp80
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP51:%.*]] = phi x86_fp80 [ [[TMP50]], [[ITOFP_IF_END26]] ], [ 0xK00000000000000000000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret x86_fp80 [[TMP51]]
+;
+  %conv = sitofp i129 %a to x86_fp80
+  ret x86_fp80 %conv
+}
+
+define fp128 @si129tofp128(i129 %a) {
+; CHECK-LABEL: @si129tofp128(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[TMP3]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i129 129, [[TMP4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i129 128, [[TMP4]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i129 [[TMP7]], 113
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i129 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i129 114, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i129 115, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[TMP3]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i129 14, [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = lshr i129 [[TMP3]], [[TMP10]]
+; CHECK-NEXT:    [[TMP12:%.*]] = add i129 [[TMP4]], 115
+; CHECK-NEXT:    [[TMP13:%.*]] = lshr i129 -1, [[TMP12]]
+; CHECK-NEXT:    [[TMP14:%.*]] = and i129 [[TMP13]], [[TMP3]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp ne i129 [[TMP14]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = zext i1 [[TMP15]] to i129
+; CHECK-NEXT:    [[TMP17:%.*]] = or i129 [[TMP11]], [[TMP16]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP18:%.*]] = phi i129 [ [[TMP17]], [[ITOFP_SW_DEFAULT]] ], [ [[TMP3]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP19:%.*]] = trunc i129 [[TMP18]] to i32
+; CHECK-NEXT:    [[TMP20:%.*]] = lshr i32 [[TMP19]], 2
+; CHECK-NEXT:    [[TMP21:%.*]] = and i32 [[TMP20]], 1
+; CHECK-NEXT:    [[TMP22:%.*]] = zext i32 [[TMP21]] to i129
+; CHECK-NEXT:    [[TMP23:%.*]] = or i129 [[TMP18]], [[TMP22]]
+; CHECK-NEXT:    [[TMP24:%.*]] = add i129 [[TMP23]], 1
+; CHECK-NEXT:    [[TMP25:%.*]] = ashr i129 [[TMP24]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP24]], 41538374868278621028243970633760768
+; CHECK-NEXT:    [[TMP26:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP27:%.*]] = trunc i129 [[TMP25]] to i128
+; CHECK-NEXT:    [[TMP28:%.*]] = lshr i129 [[TMP25]], 32
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br i1 [[TMP26]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP30:%.*]] = ashr i129 [[TMP24]], 3
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i128
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP30]], 32
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP6]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP34:%.*]] = add i129 [[TMP4]], 4294967280
+; CHECK-NEXT:    [[TMP35:%.*]] = shl i129 [[TMP3]], [[TMP34]]
+; CHECK-NEXT:    [[TMP36:%.*]] = trunc i129 [[TMP35]] to i128
+; CHECK-NEXT:    [[TMP37:%.*]] = lshr i129 [[TMP35]], 32
+; CHECK-NEXT:    [[TMP38:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP39:%.*]] = phi i128 [ [[TMP31]], [[ITOFP_IF_THEN20]] ], [ [[TMP27]], [[ITOFP_SW_EPILOG]] ], [ [[TMP36]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP40:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP38]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[AND29:%.*]] = and i129 [[TMP1]], 9223372036854775808
+; CHECK-NEXT:    [[TMP41:%.*]] = shl i64 [[TMP40]], 48
+; CHECK-NEXT:    [[TMP42:%.*]] = add i64 [[TMP41]], 4611404543450677248
+; CHECK-NEXT:    [[TMP43:%.*]] = zext i64 [[TMP42]] to i128
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[AND29]] to i128
+; CHECK-NEXT:    [[TMP45:%.*]] = or i128 [[TMP44]], [[TMP43]]
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i128 [[TMP45]], 64
+; CHECK-NEXT:    [[TMP47:%.*]] = and i128 [[TMP39]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP48:%.*]] = or i128 [[TMP46]], [[TMP47]]
+; CHECK-NEXT:    [[TMP49:%.*]] = bitcast i128 [[TMP48]] to fp128
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP50:%.*]] = phi fp128 [ [[TMP49]], [[ITOFP_IF_END26]] ], [ 0xL00000000000000000000000000000000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret fp128 [[TMP50]]
+;
+  %conv = sitofp i129 %a to fp128
+  ret fp128 %conv
+}
diff --git a/llvm/test/CodeGen/X86/expand-large-fp-convert-ui129tofp.ll b/llvm/test/CodeGen/X86/expand-large-fp-convert-ui129tofp.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/expand-large-fp-convert-ui129tofp.ll
@@ -0,0 +1,427 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -mtriple=x86_64-- -expand-large-fp-convert < %s | FileCheck %s
+
+define half @ui129tohalf(i129 %a) {
+; CHECK-LABEL: @ui129tohalf(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[A]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 24
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 25, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 26, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[A]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 103, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[A]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 26
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[A]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[A]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = lshr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 67108864
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i32
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i32
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -105
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[A]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i32
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i32 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP45:%.*]] = and i32 [[TMP44]], -2147483648
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i32 [[TMP43]], 23
+; CHECK-NEXT:    [[TMP47:%.*]] = add i32 [[TMP46]], 1065353216
+; CHECK-NEXT:    [[TMP48:%.*]] = and i32 [[TMP42]], 8388607
+; CHECK-NEXT:    [[TMP49:%.*]] = or i32 [[TMP48]], [[TMP45]]
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP48]], [[TMP47]]
+; CHECK-NEXT:    [[TMP51:%.*]] = bitcast i32 [[TMP50]] to float
+; CHECK-NEXT:    [[TMP52:%.*]] = fptrunc float [[TMP51]] to half
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP53:%.*]] = phi half [ [[TMP52]], [[ITOFP_IF_END26]] ], [ 0xH0000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret half [[TMP53]]
+;
+  %conv = uitofp i129 %a to half
+  ret half %conv
+}
+
+define float @ui129tofloat(i129 %a) {
+; CHECK-LABEL: @ui129tofloat(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[A]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 24
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 25, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 26, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[A]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 103, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[A]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 26
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[A]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[A]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = lshr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 67108864
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i32
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i32
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -105
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[A]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i32
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i32 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP45:%.*]] = and i32 [[TMP44]], -2147483648
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i32 [[TMP43]], 23
+; CHECK-NEXT:    [[TMP47:%.*]] = add i32 [[TMP46]], 1065353216
+; CHECK-NEXT:    [[TMP48:%.*]] = and i32 [[TMP42]], 8388607
+; CHECK-NEXT:    [[TMP49:%.*]] = or i32 [[TMP48]], [[TMP45]]
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP48]], [[TMP47]]
+; CHECK-NEXT:    [[TMP51:%.*]] = bitcast i32 [[TMP50]] to float
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP52:%.*]] = phi float [ [[TMP51]], [[ITOFP_IF_END26]] ], [ 0.000000e+00, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[TMP52]]
+;
+  %conv = uitofp i129 %a to float
+  ret float %conv
+}
+
+define double @ui129todouble(i129 %a) {
+; CHECK-LABEL: @ui129todouble(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[A]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i32 129, [[TMP5]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i32 128, [[TMP5]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[TMP7]], 53
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i32 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i32 54, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i32 55, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[A]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i32 74, [[TMP5]]
+; CHECK-NEXT:    [[TMP11:%.*]] = zext i32 [[TMP10]] to i129
+; CHECK-NEXT:    [[TMP12:%.*]] = lshr i129 [[A]], [[TMP11]]
+; CHECK-NEXT:    [[TMP13:%.*]] = add i32 [[TMP5]], 55
+; CHECK-NEXT:    [[TMP14:%.*]] = zext i32 [[TMP13]] to i129
+; CHECK-NEXT:    [[TMP15:%.*]] = lshr i129 -1, [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = and i129 [[TMP15]], [[A]]
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp ne i129 [[TMP16]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = zext i1 [[TMP17]] to i129
+; CHECK-NEXT:    [[TMP19:%.*]] = or i129 [[TMP12]], [[TMP18]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP20:%.*]] = phi i129 [ [[TMP19]], [[ITOFP_SW_DEFAULT]] ], [ [[A]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP21:%.*]] = trunc i129 [[TMP20]] to i32
+; CHECK-NEXT:    [[TMP22:%.*]] = lshr i32 [[TMP21]], 2
+; CHECK-NEXT:    [[TMP23:%.*]] = and i32 [[TMP22]], 1
+; CHECK-NEXT:    [[TMP24:%.*]] = zext i32 [[TMP23]] to i129
+; CHECK-NEXT:    [[TMP25:%.*]] = or i129 [[TMP20]], [[TMP24]]
+; CHECK-NEXT:    [[TMP26:%.*]] = add i129 [[TMP25]], 1
+; CHECK-NEXT:    [[TMP27:%.*]] = lshr i129 [[TMP26]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP26]], 36028797018963968
+; CHECK-NEXT:    [[TMP28:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP27]] to i64
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP27]], 32
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i32
+; CHECK-NEXT:    br i1 [[TMP28]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP26]], 3
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP32]] to i64
+; CHECK-NEXT:    [[TMP34:%.*]] = lshr i129 [[TMP32]], 32
+; CHECK-NEXT:    [[TMP35:%.*]] = trunc i129 [[TMP34]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP36:%.*]] = add i32 [[TMP5]], -76
+; CHECK-NEXT:    [[TMP37:%.*]] = zext i32 [[TMP36]] to i129
+; CHECK-NEXT:    [[TMP38:%.*]] = shl i129 [[A]], [[TMP37]]
+; CHECK-NEXT:    [[TMP39:%.*]] = trunc i129 [[TMP38]] to i64
+; CHECK-NEXT:    [[TMP40:%.*]] = lshr i129 [[TMP38]], 32
+; CHECK-NEXT:    [[TMP41:%.*]] = trunc i129 [[TMP40]] to i32
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP42:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP39]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP43:%.*]] = phi i32 [ [[TMP35]], [[ITOFP_IF_THEN20]] ], [ [[TMP31]], [[ITOFP_SW_EPILOG]] ], [ [[TMP41]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP44:%.*]] = phi i32 [ [[TMP6]], [[ITOFP_IF_THEN20]] ], [ [[TMP7]], [[ITOFP_SW_EPILOG]] ], [ [[TMP7]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP45:%.*]] = trunc i129 [[TMP1]] to i32
+; CHECK-NEXT:    [[TMP46:%.*]] = and i32 [[TMP45]], -2147483648
+; CHECK-NEXT:    [[TMP47:%.*]] = shl i32 [[TMP44]], 20
+; CHECK-NEXT:    [[TMP48:%.*]] = add i32 [[TMP47]], 1072693248
+; CHECK-NEXT:    [[TMP49:%.*]] = and i32 [[TMP43]], 1048575
+; CHECK-NEXT:    [[TMP50:%.*]] = or i32 [[TMP49]], [[TMP46]]
+; CHECK-NEXT:    [[TMP51:%.*]] = or i32 [[TMP49]], [[TMP48]]
+; CHECK-NEXT:    [[TMP52:%.*]] = zext i32 [[TMP51]] to i64
+; CHECK-NEXT:    [[TMP53:%.*]] = shl i64 [[TMP52]], 32
+; CHECK-NEXT:    [[TMP54:%.*]] = and i64 [[TMP42]], 4294967295
+; CHECK-NEXT:    [[TMP55:%.*]] = or i64 [[TMP53]], [[TMP54]]
+; CHECK-NEXT:    [[TMP56:%.*]] = bitcast i64 [[TMP55]] to double
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP57:%.*]] = phi double [ [[TMP56]], [[ITOFP_IF_END26]] ], [ 0.000000e+00, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret double [[TMP57]]
+;
+  %conv = uitofp i129 %a to double
+  ret double %conv
+}
+
+define x86_fp80 @ui129tox86_fp80(i129 %a) {
+; CHECK-LABEL: @ui129tox86_fp80(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[A]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i129 129, [[TMP4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i129 128, [[TMP4]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i129 [[TMP7]], 113
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i129 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i129 114, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i129 115, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[A]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i129 14, [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = lshr i129 [[A]], [[TMP10]]
+; CHECK-NEXT:    [[TMP12:%.*]] = add i129 [[TMP4]], 115
+; CHECK-NEXT:    [[TMP13:%.*]] = lshr i129 -1, [[TMP12]]
+; CHECK-NEXT:    [[TMP14:%.*]] = and i129 [[TMP13]], [[A]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp ne i129 [[TMP14]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = zext i1 [[TMP15]] to i129
+; CHECK-NEXT:    [[TMP17:%.*]] = or i129 [[TMP11]], [[TMP16]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP18:%.*]] = phi i129 [ [[TMP17]], [[ITOFP_SW_DEFAULT]] ], [ [[A]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP19:%.*]] = trunc i129 [[TMP18]] to i32
+; CHECK-NEXT:    [[TMP20:%.*]] = lshr i32 [[TMP19]], 2
+; CHECK-NEXT:    [[TMP21:%.*]] = and i32 [[TMP20]], 1
+; CHECK-NEXT:    [[TMP22:%.*]] = zext i32 [[TMP21]] to i129
+; CHECK-NEXT:    [[TMP23:%.*]] = or i129 [[TMP18]], [[TMP22]]
+; CHECK-NEXT:    [[TMP24:%.*]] = add i129 [[TMP23]], 1
+; CHECK-NEXT:    [[TMP25:%.*]] = lshr i129 [[TMP24]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP24]], 41538374868278621028243970633760768
+; CHECK-NEXT:    [[TMP26:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP27:%.*]] = trunc i129 [[TMP25]] to i128
+; CHECK-NEXT:    [[TMP28:%.*]] = lshr i129 [[TMP25]], 32
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br i1 [[TMP26]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP24]], 3
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i128
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP30]], 32
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP6]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP34:%.*]] = add i129 [[TMP4]], 4294967280
+; CHECK-NEXT:    [[TMP35:%.*]] = shl i129 [[A]], [[TMP34]]
+; CHECK-NEXT:    [[TMP36:%.*]] = trunc i129 [[TMP35]] to i128
+; CHECK-NEXT:    [[TMP37:%.*]] = lshr i129 [[TMP35]], 32
+; CHECK-NEXT:    [[TMP38:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP39:%.*]] = phi i128 [ [[TMP31]], [[ITOFP_IF_THEN20]] ], [ [[TMP27]], [[ITOFP_SW_EPILOG]] ], [ [[TMP36]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP40:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP38]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[AND29:%.*]] = and i129 [[TMP1]], 9223372036854775808
+; CHECK-NEXT:    [[TMP41:%.*]] = shl i64 [[TMP40]], 48
+; CHECK-NEXT:    [[TMP42:%.*]] = add i64 [[TMP41]], 4611404543450677248
+; CHECK-NEXT:    [[TMP43:%.*]] = zext i64 [[TMP42]] to i128
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[AND29]] to i128
+; CHECK-NEXT:    [[TMP45:%.*]] = or i128 [[TMP44]], [[TMP43]]
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i128 [[TMP45]], 64
+; CHECK-NEXT:    [[TMP47:%.*]] = and i128 [[TMP39]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP48:%.*]] = or i128 [[TMP46]], [[TMP47]]
+; CHECK-NEXT:    [[TMP49:%.*]] = bitcast i128 [[TMP48]] to fp128
+; CHECK-NEXT:    [[TMP50:%.*]] = fptrunc fp128 [[TMP49]] to x86_fp80
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP51:%.*]] = phi x86_fp80 [ [[TMP50]], [[ITOFP_IF_END26]] ], [ 0xK00000000000000000000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret x86_fp80 [[TMP51]]
+;
+  %conv = uitofp i129 %a to x86_fp80
+  ret x86_fp80 %conv
+}
+
+define fp128 @ui129tofp128(i129 %a) {
+; CHECK-LABEL: @ui129tofp128(
+; CHECK-NEXT:  itofp-entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i129 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ITOFP_RETURN:%.*]], label [[ITOFP_IF_END:%.*]]
+; CHECK:       itofp-if-end:
+; CHECK-NEXT:    [[TMP1:%.*]] = ashr i129 [[A]], 128
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i129 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[TMP3:%.*]] = sub i129 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = call i129 @llvm.ctlz.i129(i129 [[A]], i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = trunc i129 [[TMP4]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = sub i129 129, [[TMP4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = sub i129 128, [[TMP4]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i129 [[TMP7]], 113
+; CHECK-NEXT:    br i1 [[TMP8]], label [[ITOFP_IF_THEN4:%.*]], label [[ITOFP_IF_ELSE:%.*]]
+; CHECK:       itofp-if-then4:
+; CHECK-NEXT:    switch i129 [[TMP6]], label [[ITOFP_SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i129 114, label [[ITOFP_SW_BB:%.*]]
+; CHECK-NEXT:    i129 115, label [[ITOFP_SW_EPILOG:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       itofp-sw-bb:
+; CHECK-NEXT:    [[TMP9:%.*]] = shl i129 [[A]], 1
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-default:
+; CHECK-NEXT:    [[TMP10:%.*]] = sub i129 14, [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = lshr i129 [[A]], [[TMP10]]
+; CHECK-NEXT:    [[TMP12:%.*]] = add i129 [[TMP4]], 115
+; CHECK-NEXT:    [[TMP13:%.*]] = lshr i129 -1, [[TMP12]]
+; CHECK-NEXT:    [[TMP14:%.*]] = and i129 [[TMP13]], [[A]]
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp ne i129 [[TMP14]], 0
+; CHECK-NEXT:    [[TMP16:%.*]] = zext i1 [[TMP15]] to i129
+; CHECK-NEXT:    [[TMP17:%.*]] = or i129 [[TMP11]], [[TMP16]]
+; CHECK-NEXT:    br label [[ITOFP_SW_EPILOG]]
+; CHECK:       itofp-sw-epilog:
+; CHECK-NEXT:    [[TMP18:%.*]] = phi i129 [ [[TMP17]], [[ITOFP_SW_DEFAULT]] ], [ [[A]], [[ITOFP_IF_THEN4]] ], [ [[TMP9]], [[ITOFP_SW_BB]] ]
+; CHECK-NEXT:    [[TMP19:%.*]] = trunc i129 [[TMP18]] to i32
+; CHECK-NEXT:    [[TMP20:%.*]] = lshr i32 [[TMP19]], 2
+; CHECK-NEXT:    [[TMP21:%.*]] = and i32 [[TMP20]], 1
+; CHECK-NEXT:    [[TMP22:%.*]] = zext i32 [[TMP21]] to i129
+; CHECK-NEXT:    [[TMP23:%.*]] = or i129 [[TMP18]], [[TMP22]]
+; CHECK-NEXT:    [[TMP24:%.*]] = add i129 [[TMP23]], 1
+; CHECK-NEXT:    [[TMP25:%.*]] = lshr i129 [[TMP24]], 2
+; CHECK-NEXT:    [[A3:%.*]] = and i129 [[TMP24]], 41538374868278621028243970633760768
+; CHECK-NEXT:    [[TMP26:%.*]] = icmp eq i129 [[A3]], 0
+; CHECK-NEXT:    [[TMP27:%.*]] = trunc i129 [[TMP25]] to i128
+; CHECK-NEXT:    [[TMP28:%.*]] = lshr i129 [[TMP25]], 32
+; CHECK-NEXT:    [[TMP29:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br i1 [[TMP26]], label [[ITOFP_IF_END26:%.*]], label [[ITOFP_IF_THEN20:%.*]]
+; CHECK:       itofp-if-then20:
+; CHECK-NEXT:    [[TMP30:%.*]] = lshr i129 [[TMP24]], 3
+; CHECK-NEXT:    [[TMP31:%.*]] = trunc i129 [[TMP30]] to i128
+; CHECK-NEXT:    [[TMP32:%.*]] = lshr i129 [[TMP30]], 32
+; CHECK-NEXT:    [[TMP33:%.*]] = trunc i129 [[TMP6]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-else:
+; CHECK-NEXT:    [[TMP34:%.*]] = add i129 [[TMP4]], 4294967280
+; CHECK-NEXT:    [[TMP35:%.*]] = shl i129 [[A]], [[TMP34]]
+; CHECK-NEXT:    [[TMP36:%.*]] = trunc i129 [[TMP35]] to i128
+; CHECK-NEXT:    [[TMP37:%.*]] = lshr i129 [[TMP35]], 32
+; CHECK-NEXT:    [[TMP38:%.*]] = trunc i129 [[TMP7]] to i64
+; CHECK-NEXT:    br label [[ITOFP_IF_END26]]
+; CHECK:       itofp-if-end26:
+; CHECK-NEXT:    [[TMP39:%.*]] = phi i128 [ [[TMP31]], [[ITOFP_IF_THEN20]] ], [ [[TMP27]], [[ITOFP_SW_EPILOG]] ], [ [[TMP36]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[TMP40:%.*]] = phi i64 [ [[TMP33]], [[ITOFP_IF_THEN20]] ], [ [[TMP29]], [[ITOFP_SW_EPILOG]] ], [ [[TMP38]], [[ITOFP_IF_ELSE]] ]
+; CHECK-NEXT:    [[AND29:%.*]] = and i129 [[TMP1]], 9223372036854775808
+; CHECK-NEXT:    [[TMP41:%.*]] = shl i64 [[TMP40]], 48
+; CHECK-NEXT:    [[TMP42:%.*]] = add i64 [[TMP41]], 4611404543450677248
+; CHECK-NEXT:    [[TMP43:%.*]] = zext i64 [[TMP42]] to i128
+; CHECK-NEXT:    [[TMP44:%.*]] = trunc i129 [[AND29]] to i128
+; CHECK-NEXT:    [[TMP45:%.*]] = or i128 [[TMP44]], [[TMP43]]
+; CHECK-NEXT:    [[TMP46:%.*]] = shl i128 [[TMP45]], 64
+; CHECK-NEXT:    [[TMP47:%.*]] = and i128 [[TMP39]], 5192296858534827628530496329220095
+; CHECK-NEXT:    [[TMP48:%.*]] = or i128 [[TMP46]], [[TMP47]]
+; CHECK-NEXT:    [[TMP49:%.*]] = bitcast i128 [[TMP48]] to fp128
+; CHECK-NEXT:    br label [[ITOFP_RETURN]]
+; CHECK:       itofp-return:
+; CHECK-NEXT:    [[TMP50:%.*]] = phi fp128 [ [[TMP49]], [[ITOFP_IF_END26]] ], [ 0xL00000000000000000000000000000000, [[ITOFP_ENTRY:%.*]] ]
+; CHECK-NEXT:    ret fp128 [[TMP50]]
+;
+  %conv = uitofp i129 %a to fp128
+  ret fp128 %conv
+}
diff --git a/llvm/test/CodeGen/X86/fp-i129.ll b/llvm/test/CodeGen/X86/fp-i129.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fp-i129.ll
@@ -0,0 +1,130 @@
+; RUN: llc < %s -mtriple=i686-unknown-unknown | FileCheck %s --check-prefixes=CHECK,X86
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s --check-prefixes=CHECK,X64
+
+define i129 @fptosi_float(float %a) nounwind {
+; CHECK-LABEL: fptosi_float:
+; CHECK-NOT:     call
+  %res = fptosi float %a to i129
+  ret i129 %res
+}
+
+define i129 @fptosi_double(double %a) nounwind {
+; CHECK-LABEL: fptosi_double:
+; CHECK-NOT:     call
+  %res = fptosi double %a to i129
+  ret i129 %res
+}
+
+define i129 @fptosi_fp128(fp128 %a) nounwind {
+; CHECK-LABEL: fptosi_fp128:
+; CHECK-NOT:     call
+  %res = fptosi fp128 %a to i129
+  ret i129 %res
+}
+
+define i129 @fptoui_float(float %a) nounwind {
+; CHECK-LABEL: fptoui_float:
+; CHECK-NOT:     call
+  %res = fptoui float %a to i129
+  ret i129 %res
+}
+
+define i129 @fptoui_double(double %a) nounwind {
+; CHECK-LABEL: fptoui_double:
+; CHECK-NOT:     call
+  %res = fptoui double %a to i129
+  ret i129 %res
+}
+
+define i129 @fptoui_fp128(fp128 %a) nounwind {
+; CHECK-LABEL: fptoui_fp128:
+; CHECK-NOT:     call
+  %res = fptoui fp128 %a to i129
+  ret i129 %res
+}
+
+define float @sitofp_float(i129 %a) nounwind {
+; CHECK-LABEL: sitofp_float:
+; CHECK-NOT:     call
+  %res = sitofp i129 %a to float
+  ret float %res
+}
+
+define double @sitofp_double(i129 %a) nounwind {
+; CHECK-LABEL: sitofp_double:
+; CHECK-NOT:     call
+  %res = sitofp i129 %a to double
+  ret double %res
+}
+
+define fp128 @sitofp_fp128(i129 %a) nounwind {
+; CHECK-LABEL: sitofp_fp128:
+; CHECK-NOT:     call
+  %res = sitofp i129 %a to fp128
+  ret fp128 %res
+}
+
+define float @uitofp_float(i129 %a) nounwind {
+; CHECK-LABEL: uitofp_float:
+; CHECK-NOT:     call
+  %res = uitofp i129 %a to float
+  ret float %res
+}
+
+define double @uitofp_double(i129 %a) nounwind {
+; CHECK-LABEL: uitofp_double:
+; CHECK-NOT:     call
+  %res = uitofp i129 %a to double
+  ret double %res
+}
+
+define fp128 @uitofp_fp128(i129 %a) nounwind {
+; CHECK-LABEL: uitofp_fp128:
+; CHECK-NOT:     call
+  %res = uitofp i129 %a to fp128
+  ret fp128 %res
+}
+
+; higher sizes
+define i257 @fptosi257_double(double %a) nounwind {
+; CHECK-LABEL: fptosi257_double:
+; CHECK-NOT:     call
+  %res = fptosi double %a to i257
+  ret i257 %res
+}
+
+; half tests
+define i257 @fptosi_half(half %a) nounwind {
+; X86-LABEL: fptosi_half:
+; X86: __gnu_h2f_ieee
+;
+; X64-LABEL: fptosi_half:
+; X64: __extendhfsf2
+  %res = fptosi half %a to i257
+  ret i257 %res
+}
+
+define half @uitofp_half(i257 %a) nounwind {
+; X86-LABEL: uitofp_half:
+; X86: __gnu_f2h_ieee
+;
+; X64-LABEL: uitofp_half:
+; X64: __truncsfhf2
+  %res = uitofp i257 %a to half
+  ret half %res
+}
+
+; x86_fp80 tests
+define i257 @fptoui_x86_fp80(x86_fp80 %a) nounwind {
+; CHECK-LABEL: fptoui_x86_fp80:
+; CHECK: __extendxftf2
+  %res = fptoui x86_fp80 %a to i257
+  ret i257 %res
+}
+
+define x86_fp80 @sitofp_x86_fp80(i257 %a) nounwind {
+; CHECK-LABEL: sitofp_x86_fp80:
+; CHECK: __trunctfxf2
+  %res = sitofp i257 %a to x86_fp80
+  ret x86_fp80 %res
+}
diff --git a/llvm/test/CodeGen/X86/opt-pipeline.ll b/llvm/test/CodeGen/X86/opt-pipeline.ll
--- a/llvm/test/CodeGen/X86/opt-pipeline.ll
+++ b/llvm/test/CodeGen/X86/opt-pipeline.ll
@@ -28,6 +28,7 @@
 ; CHECK-NEXT:     Pre-ISel Intrinsic Lowering
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Expand large div/rem
+; CHECK-NEXT:       Expand large fp convert
 ; CHECK-NEXT:       Expand Atomic instructions
 ; CHECK-NEXT:       Lower AMX intrinsics
 ; CHECK-NEXT:       Lower AMX type for load/store
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -422,7 +422,8 @@
       "dot-regions",          "dot-regions-only",
       "view-regions",         "view-regions-only",
       "select-optimize",      "expand-large-div-rem",
-      "structurizecfg",       "fix-irreducible"};
+      "structurizecfg",       "fix-irreducible",
+      "expand-large-fp-convert"};
   for (const auto &P : PassNamePrefix)
     if (Pass.startswith(P))
       return true;
@@ -469,6 +470,7 @@
   // For codegen passes, only passes that do IR to IR transformation are
   // supported.
   initializeExpandLargeDivRemLegacyPassPass(Registry);
+  initializeExpandLargeFpConvertLegacyPassPass(Registry);
   initializeExpandMemCmpPassPass(Registry);
   initializeScalarizeMaskedMemIntrinLegacyPassPass(Registry);
   initializeSelectOptimizePass(Registry);