diff --git a/libc/test/src/math/exp2m1f_test.cpp b/libc/test/src/math/exp2m1f_test.cpp
@@ -0,0 +1,66 @@
+//===-- Unittests for exp2m1f ---------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/llvm-libc-macros/math-macros.h"
+#include "src/__support/CPP/array.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/exp2m1f.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+#include <stdint.h>
+
+using LlvmLibcExp2m1fTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+TEST_F(LlvmLibcExp2m1fTest, TrickyInputs) {
+  constexpr LIBC_NAMESPACE::cpp::array<float, 10> INPUTS = {
+      // EXP2M1F_EXCEPTS_LO
+      0x1.36dc8ep-36,
+      0x1.224936p-19,
+      0x1.d16d2p-20,
+      0x1.17949ep-14,
+      -0x1.9c3e1ep-38,
+      -0x1.4d89b4p-32,
+      -0x1.a6eac4p-10,
+      -0x1.e7526ep-6,
+      // EXP2M1F_EXCEPTS_HI
+      0x1.16a972p-1,
+      -0x1.9f12acp-5,
+  };
+
+  for (float x : INPUTS) {
+    LIBC_NAMESPACE::libc_errno = 0;
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp2m1, x,
+                                   LIBC_NAMESPACE::exp2m1f(x), 0.5);
+  }
+}
+
+TEST_F(LlvmLibcExp2m1fTest, InFloatRange) {
+  constexpr uint32_t COUNT = 100'000;
+  constexpr uint32_t STEP = UINT32_MAX / COUNT;
+  for (uint32_t i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+    float x = FPBits(v).get_val();
+    if (isnan(x) || isinf(x))
+      continue;
+    LIBC_NAMESPACE::libc_errno = 0;
+    float result = LIBC_NAMESPACE::exp2m1f(x);
+
+    // If the computation resulted in an error or did not produce valid result
+    // in the single-precision floating point range, then ignore comparing with
+    // MPFR result as MPFR can still produce valid results because of its
+    // wider precision.
+    if (isnan(result) || isinf(result) || LIBC_NAMESPACE::libc_errno != 0)
+      continue;
+    ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp2m1, x,
+                                   LIBC_NAMESPACE::exp2m1f(x), 0.5);
+  }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
@@ -773,6 +773,17 @@ add_fp_unittest(
    libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  exp2m1f_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    exp2m1f_test.cpp
+  DEPENDS
+    libc.src.errno.errno
+    libc.src.math.exp2m1f
+)
+
 add_fp_unittest(
   exp10f_test
   SUITE

diff --git a/libc/test/src/math/smoke/exp2m1f_test.cpp b/libc/test/src/math/smoke/exp2m1f_test.cpp
@@ -0,0 +1,63 @@
+//===-- Unittests for exp2m1f ---------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/errno/libc_errno.h"
+#include "src/math/exp2m1f.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcExp2m1fTest = LIBC_NAMESPACE::testing::FPTest<float>;
+using LIBC_NAMESPACE::fputil::testing::ForceRoundingMode;
+using LIBC_NAMESPACE::fputil::testing::RoundingMode;
+
+TEST_F(LlvmLibcExp2m1fTest, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::exp2m1f(aNaN));
+  EXPECT_FP_EQ_ALL_ROUNDING(inf, LIBC_NAMESPACE::exp2m1f(inf));
+  EXPECT_FP_EQ_ALL_ROUNDING(-1.0f, LIBC_NAMESPACE::exp2m1f(neg_inf));
+  EXPECT_FP_EQ_ALL_ROUNDING(0.0f, LIBC_NAMESPACE::exp2m1f(0.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(-0.0f, LIBC_NAMESPACE::exp2m1f(-0.0f));
+
+  EXPECT_FP_EQ_ALL_ROUNDING(1.0f, LIBC_NAMESPACE::exp2m1f(1.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(-0.5f, LIBC_NAMESPACE::exp2m1f(-1.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(3.0f, LIBC_NAMESPACE::exp2m1f(2.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(-0.75f, LIBC_NAMESPACE::exp2m1f(-2.0f));
+}
+
+TEST_F(LlvmLibcExp2m1fTest, Overflow) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.fffffep+127),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(128.0f),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.000002p+7),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+}
+
+TEST_F(LlvmLibcExp2m1fTest, Underflow) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.fffffep+127),
+                              FE_UNDERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-25.0f),
+                              FE_UNDERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.900002p4),
+                              FE_UNDERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -89,7 +89,8 @@ class MPFRNumber {
   // precision.
   template <typename XType,
             cpp::enable_if_t<cpp::is_same_v<float, XType>, int> = 0>
-  explicit MPFRNumber(XType x, int precision = ExtraPrecision<XType>::VALUE,
+  explicit MPFRNumber(XType x,
+                      unsigned int precision = ExtraPrecision<XType>::VALUE,
                       RoundingMode rounding = RoundingMode::Nearest)
       : mpfr_precision(precision),
         mpfr_rounding(get_mpfr_rounding_mode(rounding)) {
@@ -99,7 +100,8 @@ class MPFRNumber {
 
   template <typename XType,
             cpp::enable_if_t<cpp::is_same_v<double, XType>, int> = 0>
-  explicit MPFRNumber(XType x, int precision = ExtraPrecision<XType>::VALUE,
+  explicit MPFRNumber(XType x,
+                      unsigned int precision = ExtraPrecision<XType>::VALUE,
                       RoundingMode rounding = RoundingMode::Nearest)
       : mpfr_precision(precision),
         mpfr_rounding(get_mpfr_rounding_mode(rounding)) {
@@ -109,7 +111,8 @@ class MPFRNumber {
 
   template <typename XType,
             cpp::enable_if_t<cpp::is_same_v<long double, XType>, int> = 0>
-  explicit MPFRNumber(XType x, int precision = ExtraPrecision<XType>::VALUE,
+  explicit MPFRNumber(XType x,
+                      unsigned int precision = ExtraPrecision<XType>::VALUE,
                       RoundingMode rounding = RoundingMode::Nearest)
       : mpfr_precision(precision),
         mpfr_rounding(get_mpfr_rounding_mode(rounding)) {
@@ -119,7 +122,8 @@ class MPFRNumber {
 
   template <typename XType,
             cpp::enable_if_t<cpp::is_integral_v<XType>, int> = 0>
-  explicit MPFRNumber(XType x, int precision = ExtraPrecision<float>::VALUE,
+  explicit MPFRNumber(XType x,
+                      unsigned int precision = ExtraPrecision<float>::VALUE,
                       RoundingMode rounding = RoundingMode::Nearest)
       : mpfr_precision(precision),
         mpfr_rounding(get_mpfr_rounding_mode(rounding)) {
@@ -134,6 +138,12 @@ class MPFRNumber {
     mpfr_set(value, other.value, mpfr_rounding);
   }
 
+  MPFRNumber(const MPFRNumber &other, unsigned int precision)
+      : mpfr_precision(precision), mpfr_rounding(other.mpfr_rounding) {
+    mpfr_init2(value, mpfr_precision);
+    mpfr_set(value, other.value, mpfr_rounding);
+  }
+
   ~MPFRNumber() { mpfr_clear(value); }
 
   MPFRNumber &operator=(const MPFRNumber &rhs) {
@@ -229,6 +239,36 @@ class MPFRNumber {
     return result;
   }
 
+  MPFRNumber exp2m1() const {
+    // TODO: Only use mpfr_exp2m1 once CI and buildbots get MPFR >= 4.2.0.
+#if MPFR_VERSION_MAJOR > 4 ||                                                  \
+    (MPFR_VERSION_MAJOR == 4 && MPFR_VERSION_MINOR >= 2)
+    MPFRNumber result(*this);
+    mpfr_exp2m1(result.value, value, mpfr_rounding);
+    return result;
+#else
+    unsigned int prec = mpfr_precision * 3;
+    MPFRNumber result(*this, prec);
+
+    float f = mpfr_get_flt(abs().value, mpfr_rounding);
+    if (f > 0.5f && f < 0x1.0p30f) {
+      mpfr_exp2(result.value, value, mpfr_rounding);
+      mpfr_sub_ui(result.value, result.value, 1, mpfr_rounding);
+      return result;
+    }
+
+    MPFRNumber ln2(2.0f, prec);
+    // log(2)
+    mpfr_log(ln2.value, ln2.value, mpfr_rounding);
+    // x * log(2)
+    mpfr_mul(result.value, value, ln2.value, mpfr_rounding);
+    // e^(x * log(2)) - 1
+    int ex = mpfr_expm1(result.value, result.value, mpfr_rounding);
+    mpfr_subnormalize(result.value, ex, mpfr_rounding);
+    return result;
+#endif
+  }
+
   MPFRNumber exp10() const {
     MPFRNumber result(*this);
     mpfr_exp10(result.value, value, mpfr_rounding);
@@ -570,6 +610,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.exp();
   case Operation::Exp2:
     return mpfrInput.exp2();
+  case Operation::Exp2m1:
+    return mpfrInput.exp2m1();
   case Operation::Exp10:
     return mpfrInput.exp10();
   case Operation::Expm1:

diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h
@@ -37,6 +37,7 @@ enum class Operation : int {
   Erf,
   Exp,
   Exp2,
+  Exp2m1,
   Exp10,
   Expm1,
   Floor,
-Original file line number
+Diff line change
@@ Expand Up / @@ -37,6 +37,7 @@ enum class Operation : int { @@
       Erf,
       Exp,
       Exp2,
+      Exp2m1,
       Exp10,
       Expm1,
       Floor,
@@ Expand Down @@