diff --git a/benchmark/CMakeLists.txt b/benchmark/CMakeLists.txt
index 90986da95c369..7253a08e7971b 100644
--- a/benchmark/CMakeLists.txt
+++ b/benchmark/CMakeLists.txt
@@ -109,6 +109,7 @@ set(SWIFT_BENCH_MODULES
     single-source/IndexPathTest
     single-source/InsertCharacter
     single-source/IntegerParsing
+    single-source/IntegerToString
     single-source/Integrate
     single-source/IterateData
     single-source/Join
diff --git a/benchmark/single-source/IntegerToString.swift b/benchmark/single-source/IntegerToString.swift
new file mode 100644
index 0000000000000..a126344c36461
--- /dev/null
+++ b/benchmark/single-source/IntegerToString.swift
@@ -0,0 +1,631 @@
+//===--- IntegerToString.swift --------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+// This test verifies the performance of generating a text description from an
+// integer value.
+
+import TestsUtils
+
+public var benchmarks: [BenchmarkInfo] {
+  var result = [
+    BenchmarkInfo(
+      name: "IntegerToString.Int.decimal",
+      runFunction: run_IntegerToString_Int_decimal,
+      tags: [.validation, .api, .runtime, .String]
+    ),
+    BenchmarkInfo(
+      name: "IntegerToString.Int.hex",
+      runFunction: run_IntegerToString_Int_hex,
+      tags: [.validation, .api, .runtime, .String]
+    ),
+    BenchmarkInfo(
+      name: "IntegerToString.UInt64.decimal",
+      runFunction: run_IntegerToString_UInt64_decimal,
+      tags: [.validation, .api, .runtime, .String]
+    ),
+    BenchmarkInfo(
+      name: "IntegerToString.UInt64.hex",
+      runFunction: run_IntegerToString_UInt64_hex,
+      tags: [.validation, .api, .runtime, .String]
+    ),
+  ]
+
+  if #available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *) {
+    result.append(
+      BenchmarkInfo(
+        name: "IntegerToString.UInt128.decimal",
+        runFunction: run_IntegerToString_UInt128_decimal,
+        tags: [.validation, .api, .runtime, .String]
+      )
+    )
+    result.append(
+      BenchmarkInfo(
+        name: "IntegerToString.UInt128.hex",
+        runFunction: run_IntegerToString_UInt128_hex,
+        tags: [.validation, .api, .runtime, .String]
+      )
+    )
+  }
+  return result
+}
+
+let intValues: [Int] = [
+  32225,
+  5550,
+  -11958,
+  16730,
+  19448,
+  28179,
+  -5184,
+  -27885,
+  27153,
+  -25416,
+  -27154,
+  -4803,
+  6825,
+  15717,
+  5291,
+  -8487,
+  -26981,
+  6916,
+  -5553,
+  -28076,
+  22301,
+  1491,
+  -28176,
+  -16115,
+  20647,
+  -26209,
+  15595,
+  28922,
+  -7220,
+  -21517,
+  8888,
+  -20765,
+  27880,
+  -31719,
+  -3556,
+  -20843,
+  -8609,
+  16257,
+  18387,
+  -12955,
+  -8630,
+  -4484,
+  9762,
+  -9688,
+  16790,
+  -6094,
+  -20066,
+  -10440,
+  -13443,
+  28448,
+  -2807,
+  -1873,
+  -914,
+  14952,
+  -29547,
+  -24787,
+  -16602,
+  24620,
+  19172,
+  -22991,
+  23742,
+  -25287,
+  10448,
+  -25535,
+  -29049,
+  18995,
+  -16537,
+  5373,
+  -6078,
+  8526,
+  -21691,
+  -13917,
+  -17441,
+  6693,
+  29629,
+  -19710,
+  -4516,
+  -32534,
+  -20677,
+  18593,
+  -31752,
+  16804,
+  -13985,
+  31898,
+  -17588,
+  -12856,
+  -24223,
+  20207,
+  -5175,
+  3870,
+  27002,
+  1330,
+  -15751,
+  -982,
+  18494,
+  31689,
+  171,
+  -899,
+  24639,
+  21605,
+  172985192,
+  -813952786,
+  -1665666121,
+  185810401,
+  -356282492,
+  519153229,
+  656610213,
+  1278822001,
+  -806899184,
+  -1705231884,
+  -2046890833,
+  -564271647,
+  619274021,
+  287941721,
+  -1799461947,
+  -811488170,
+  -411507304,
+  -1335207408,
+  451872020,
+  1977308146,
+  -1223008535,
+  -288428802,
+  -1711965056,
+  -2076021467,
+  2033055158,
+  -670842460,
+  -516315133,
+  -199699086,
+  542308014,
+  -1909344615,
+  -1966276726,
+  234662476,
+  1372605764,
+  846837306,
+  527863352,
+  -828202832,
+  -748730007,
+  303844984,
+  1575846438,
+  -1464774171,
+  -457036793,
+  -591358986,
+  736683526,
+  -1371505402,
+  -1877657819,
+  357175637,
+  1345614821,
+  -924747449,
+  1989761702,
+  -1726140877,
+  675720965,
+  1157431720,
+  -311213424,
+  1741720819,
+  -598671386,
+  -848833278,
+  516543823,
+  863054577,
+  -572154114,
+  -856934927,
+  537746487,
+  -94412853,
+  -1115669214,
+  -1444942135,
+  632091775,
+  -76026126,
+  1613053059,
+  -968549322,
+  -1707832029,
+  -190729631,
+  -224041540,
+  1621150201,
+  -1711677621,
+  1673737745,
+  1418108215,
+  192137803,
+  1295494861,
+  -1501091344,
+  662914426,
+  -637338429,
+  -565927039,
+  1183026219,
+  -212021598,
+  373230108,
+  -2058247717,
+  -1767818888,
+  415563634,
+  -1418400125,
+  1937805005,
+  -526432265,
+  -1502349122,
+  497749092,
+  1490946125,
+  1059845548,
+  77216342,
+  -1909565199,
+  1936370447,
+  192817000,
+  -1327925267,
+  -1420699487,
+]
+
+let uint64Values: [UInt64] = [
+  40591,
+  648,
+  47751,
+  1130,
+  26342,
+  15051,
+  30182,
+  12938,
+  17289,
+  37368,
+  60034,
+  13200,
+  50423,
+  61271,
+  8944,
+  42897,
+  2795,
+  34971,
+  49282,
+  56361,
+  14793,
+  23164,
+  27469,
+  64449,
+  50461,
+  64618,
+  14825,
+  42722,
+  34371,
+  11250,
+  7160,
+  63458,
+  14837,
+  37036,
+  53854,
+  26340,
+  24874,
+  34369,
+  7332,
+  55162,
+  6176,
+  45935,
+  54363,
+  23912,
+  987,
+  20126,
+  39147,
+  49583,
+  18231,
+  5667,
+  30895,
+  12447,
+  31660,
+  30333,
+  33278,
+  29789,
+  21532,
+  52725,
+  54855,
+  32545,
+  58286,
+  35152,
+  53646,
+  45702,
+  14329,
+  54188,
+  23135,
+  41244,
+  22401,
+  14784,
+  675,
+  18229,
+  41789,
+  58803,
+  244,
+  18288,
+  28003,
+  6112,
+  30579,
+  11306,
+  62321,
+  42339,
+  8323,
+  35944,
+  61043,
+  16153,
+  29107,
+  21502,
+  6883,
+  55122,
+  20687,
+  60187,
+  42816,
+  30866,
+  30155,
+  25276,
+  63954,
+  38148,
+  45019,
+  50680,
+  15052200827858995124,
+  15535239661815840417,
+  2149457961867388524,
+  12814358425672034158,
+  11729740424668659213,
+  17844894807721497052,
+  11423080310898253432,
+  10965749284831990256,
+  10916494852158064740,
+  12469842768891239891,
+  1513311992976088619,
+  13617884549524725528,
+  533860236860692248,
+  7712049449353836278,
+  4960147471138276736,
+  16926361609825180911,
+  15068400719203060266,
+  8417038304930505439,
+  13245062872331676835,
+  6424884389759218927,
+  5961748345383013434,
+  16815715321918143028,
+  604315460097471698,
+  459934484026707022,
+  9808044054531991973,
+  6459232136981853232,
+  17810913071719024129,
+  11261097629093504173,
+  4931006069659269673,
+  2157280141234011162,
+  1112725691570208272,
+  9448584584882882851,
+  14729367995151763490,
+  16521921619268042500,
+  14843656943729378712,
+  17321837091553447968,
+  4132541032525891440,
+  4486890304186743693,
+  4236474307326220888,
+  1868735020734178432,
+  9102807780937508528,
+  12184568678008594796,
+  9967694486957948860,
+  17859084903021488220,
+  9846746388495416233,
+  8803048912921415034,
+  10349958310284701040,
+  4730714293313618055,
+  18097055857882902700,
+  17328222097651726003,
+  13203817601810060088,
+  2094699121549942609,
+  8476477969794671415,
+  17258107258926342578,
+  14128822154282480330,
+  4892391481740347145,
+  13181152331462816702,
+  3625065524250038171,
+  1619809144995912262,
+  13137462691117269747,
+  9189151219995447797,
+  4010389930147109246,
+  8383993102354774029,
+  10003270414816818325,
+  5833899563959156305,
+  18145830297993779151,
+  10021947356937484992,
+  14787010438567658715,
+  11769252621531288267,
+  3568200047672438073,
+  17540143499494125889,
+  12706758128026446125,
+  6985996994118341105,
+  14812986274208565444,
+  4144609439360165223,
+  15711687169455084514,
+  14785063337094317578,
+  10093819834928293597,
+  17308402634598587341,
+  9453946139467408203,
+  8386139843424576389,
+  17376610657957319884,
+  1351317592609775051,
+  7902150678185490998,
+  16948127234906961413,
+  14533817965951347865,
+  6245398895839911653,
+  5313267148598246580,
+  15735577773932549567,
+  2888666416343902415,
+  3881752705078998798,
+  13683501860868173977,
+  12237654837394101036,
+  7946311886539093727,
+  17309286086783727919,
+  13189540567106059382,
+  2212063115889748914,
+  4606561406255833845,
+  13254437290762082565,
+  17951815598335230834,
+]
+
+@available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *)
+extension UInt128 {
+  static var _values: [UInt128] {
+    return [
+      36486133715007284564051293326217832333,
+      304267833797578007957957581978974068499,
+      109881301001772865528086566434944430682,
+      225888040458180740498287662078515922015,
+      164534375572811620306521954986782800226,
+      248312824448870212327604727539082799462,
+      151659986788138065396574835765204195139,
+      13723116692520641350788951975726777670,
+      278099561980080882629829046074700102617,
+      43611395319615150510489494560201029806,
+      271671690945284772870687425060116262050,
+      147021325216068315557209252618900046135,
+      331474194590916571616373139450048533630,
+      24049443526263318541449695668028762302,
+      265976773780110738543033028413475085191,
+      173091663064191866364155115382519117500,
+      273925537891612720187993689136218212851,
+      243505640527110247377122072745298637911,
+      72213604316012784191255043477783855972,
+      49422702112416837085419817098851400310,
+      205472953653809480491088753299587425277,
+      137803173366712757997429447653727933292,
+      310894969878565974219526051266804224120,
+      39310595981499779846991125127623032759,
+      220948984899922060113131182879908268096,
+      294266290594410269061369165655535723046,
+      188827910899191130320995191218825857434,
+      21251611286023476276984315263897921259,
+      79974028828191009145421972086630354541,
+      77801535254714305665903565986591232705,
+      169824093181153607284747946991580692960,
+      223517057121755497707143171304065884078,
+      247115749390089602428776783121803298476,
+      92097884128464815170556127644177190730,
+      184857041578877412278557101383872889215,
+      89091956798806543642434675770382477898,
+      79929732112360183757064173145268506600,
+      133144661480026552165531067985206140246,
+      202280294922209823748109273687295993734,
+      250659921128321391895121116027712968266,
+      15099865137588852647793657956057950810,
+      121051099536529385211916847609587092519,
+      33729362422406845448526273229964979135,
+      247664457924359173190964755256262008695,
+      72484317849372248906068561544960865192,
+      147198565194719741247922989833107979125,
+      239110002179008701310121332444762103815,
+      60749654316560216940575769146040456058,
+      91291701919780827984693762351441946807,
+      237088953668773371509123975314546299213,
+      195602545414002629973025020680204559110,
+      40036923152119365002904850119018218254,
+      174265226883707350605146093261612297056,
+      238411197980524712356302335208001357216,
+      13607769544676391324611927479512233414,
+      22397353926508607040358095652489366326,
+      72663303245598124621031149891911436285,
+      199572926886549222288653903087354253792,
+      169989962890466329477644026778867941417,
+      314067664755982010072336582813647420380,
+      24386984674354615568649551918272164114,
+      327081484406343721530400526147937819613,
+      320806207722331329458451238529869101392,
+      261532919963917468736956493980018484442,
+      107045023675125816373002762402636263502,
+      240185758507934917611105700716539411453,
+      13708777018090371602215940281314169231,
+      140802811127263014076476258334406381943,
+      18564710871282170005145304262666895728,
+      285905895196831302786638031663391127028,
+      134727568829868463823380048060689755538,
+      214770637321725907390984940306204173706,
+      232559098299332238825902343913290371782,
+      148880979909460536260588483506781207405,
+      128870124233958565323058083856837656936,
+      96786480218539387303576074265723345358,
+      150696370188037235545582604968523003438,
+      17597468627522476345950788480213687037,
+      172632387797748848918818205463370781812,
+      59946654480271286555097119339910428342,
+      240845859753182795016428846456886012774,
+      283280329754803336937423076191391662330,
+      269149230865210296866902079867339470046,
+      78596114630871985423328610608681967846,
+      268278942306959745167911087500423419609,
+      257743714263065635391901559220149363279,
+      145421064653226539178721957124838039442,
+      178529356525517040750328126835452619782,
+      42274659769744711573895913136965971236,
+      70372292310600526032671342341226468891,
+      63028674510203260240907221921907683643,
+      241881060130886425378022303332112077288,
+      54625024179246784376179127060398755154,
+      219391065510237145522446361299097287105,
+      237941381670743922501810952663739113914,
+      19434856143627981185033477494786433645,
+      197125814686346135623800062558015206910,
+      339686862618755498607335053241557344177,
+      218424385760691732246344016489643111843,
+      119126703470689148170122928115934911731,
+    ]
+  }
+}
+
+@inline(never)
+public func run_IntegerToString_Int_decimal(n: Int) {
+  for _ in 0..<(n*10) {
+    for x in intValues {
+      blackHole(String(x, radix: 10))
+    }
+  }
+}
+
+@inline(never)
+public func run_IntegerToString_Int_hex(n: Int) {
+  for _ in 0..<(n*10) {
+    for x in intValues {
+      blackHole(String(x, radix: 16))
+    }
+  }
+}
+
+@inline(never)
+public func run_IntegerToString_UInt64_decimal(n: Int) {
+  for _ in 0..<(n*10) {
+    for x in uint64Values {
+      blackHole(String(x, radix: 10))
+    }
+  }
+}
+
+@inline(never)
+public func run_IntegerToString_UInt64_hex(n: Int) {
+  for _ in 0..<(n*10) {
+    for x in uint64Values {
+      blackHole(String(x, radix: 16))
+    }
+  }
+}
+
+@available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *)
+@inline(never)
+public func run_IntegerToString_UInt128_decimal(n: Int) {
+  let uint128Values = UInt128._values
+  for _ in 0..<n {
+    for x in uint128Values {
+      blackHole(String(x, radix: 10))
+    }
+  }
+}
+
+@available(macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0, *)
+@inline(never)
+public func run_IntegerToString_UInt128_hex(n: Int) {
+  let uint128Values = UInt128._values
+  for _ in 0..<n {
+    for x in uint128Values {
+      blackHole(String(x, radix: 16))
+    }
+  }
+}
diff --git a/benchmark/utils/main.swift b/benchmark/utils/main.swift
index 0fcb72ba1b6a7..ed83c11c9c0e8 100644
--- a/benchmark/utils/main.swift
+++ b/benchmark/utils/main.swift
@@ -106,6 +106,7 @@ import HTTP2StateMachine
 import IndexPathTest
 import InsertCharacter
 import IntegerParsing
+import IntegerToString
 import Integrate
 import IterateData
 import Join
@@ -306,6 +307,7 @@ register(HTTP2StateMachine.benchmarks)
 register(IndexPathTest.benchmarks)
 register(InsertCharacter.benchmarks)
 register(IntegerParsing.benchmarks)
+register(IntegerToString.benchmarks)
 register(Integrate.benchmarks)
 register(IterateData.benchmarks)
 register(Join.benchmarks)