[libc][freebsd] initialize freebsd support (#124459)

Initialize FreeBSD support. Currently, only overlay build (mainly math routines) is supported. This PR mainly define the target entrypoints and basic syscall support. Different from Linux, FreeBSD's syscall return always consist of two component: - return value as arch register - error flag On x86-64, the flag is returned via the carry bit state. Hence, for syscall stubs, we always return a structure containing these two fields. For math support, the only big difference is that FreeBSD has different naming convention in some exception macros. Further fixes for C++ userland are tracked in #197605 Assisted-by: Codex with gpt-5.5 high fast
2026-05-19 13:04:34 -07:00 · 2026-05-19 13:04:34 -07:00 · 633539bfa1
commit 633539bfa1
parent 5adc8ea56d
27 changed files with 1445 additions and 9 deletions
--- a/.github/workflows/libc-freebsd-vm-tests.yml
+++ b/.github/workflows/libc-freebsd-vm-tests.yml
@ -0,0 +1,64 @@
+# This workflow is for pre-commit testing of the LLVM-libc project.
+name: LLVM-libc Pre-commit Overlay Tests (FreeBSD VM)
+permissions:
+  contents: read
+on:
+  pull_request:
+    branches: [ "main" ]
+    paths:
+      - 'libc/**'
+      - '.github/workflows/libc-freebsd-vm-tests.yml'
+
+jobs:
+  build:
+    runs-on: ubuntu-24.04
+    
+    steps:
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      with:
+        persist-credentials: false
+    
+    # MPFR is required by some of the mathlib tests.
+    - name: Setup FreeBSD
+      uses: vmactions/freebsd-vm@5b592a73e766fea2379264365f3a1a6b089ec989
+      with:
+        usesh: true
+        sync: nfs
+        release: "15.0"
+        mem: 12288
+        run: |
+          pkg update
+          pkg upgrade -y
+          pkg install -y mpfr gmp mpc ninja cmake llvm22 python3
+
+    # Use MinSizeRel to reduce the size of the build.
+    # Notice that CMP0141=NEW and MSVC_DEBUG_INFORMATION_FORMAT=Embedded are required
+    # by the sccache tool.
+    - name: Configure CMake
+      shell: freebsd {0}
+      run: >
+        cmake -B build
+        -DCMAKE_CXX_COMPILER=clang++22
+        -DCMAKE_C_COMPILER=clang22
+        -DCMAKE_BUILD_TYPE=RelWithDebInfo
+        -DLLVM_ENABLE_RUNTIMES=libc
+        -DLLVM_LIBC_MPFR_INSTALL_PATH=/usr/local
+        -DLIBC_MPC_INSTALL_PATH=/usr/local
+        -G Ninja
+        -S runtimes
+
+    - name: Build
+      shell: freebsd {0}
+      run: >
+        cmake 
+        --build build
+        --parallel 
+        --target libc
+
+    - name: Test
+      shell: freebsd {0}
+      run: >
+        cmake 
+        --build build
+        --parallel 
+        --target check-libc
--- a/libc/Maintainers.md
+++ b/libc/Maintainers.md
@ -29,7 +29,7 @@ This file is a list of the [maintainers](https://llvm.org/docs/DeveloperPolicy.h
 - Nicolas Celik
 - its.overmighty@gmail.com (email), [OverMighty](https://github.com/overmighty) (github)

-## Threading
+## Threading, FreeBSD
 - Yifan Zhu
 - yifanzhu@rochester.edu (email), [Schrodinger ZHU Yifan](https://github.com/schrodingerzhu) (github)

--- a/libc/cmake/modules/LLVMLibCArchitectures.cmake
+++ b/libc/cmake/modules/LLVMLibCArchitectures.cmake
@ -59,11 +59,15 @@ function(get_arch_and_system_from_triple triple arch_var sys_var)

  set(${arch_var} ${target_arch} PARENT_SCOPE)
  list(GET triple_comps ${system_index} target_sys)
+  list(GET triple_comps 2 target_os)

  # Correcting OS name for Apple's systems.
  if(target_sys STREQUAL "apple")
    list(GET triple_comps 2 target_sys)
  endif()
+  if(target_os MATCHES "^freebsd")
+    set(target_sys ${target_os})
+  endif()
  # Strip version from `darwin###`
  if(target_sys MATCHES "^darwin")
    set(target_sys "darwin")
@ -209,6 +213,9 @@ elseif(LIBC_TARGET_OS STREQUAL "darwin")
  set(LIBC_TARGET_OS_IS_DARWIN TRUE)
 elseif(LIBC_TARGET_OS STREQUAL "windows")
  set(LIBC_TARGET_OS_IS_WINDOWS TRUE)
+elseif(LIBC_TARGET_OS MATCHES "^freebsd.*")
+  set(LIBC_TARGET_OS_IS_FREEBSD TRUE)
+  set(LIBC_TARGET_OS "freebsd")
 elseif(LIBC_TARGET_OS STREQUAL "gpu")
  set(LIBC_TARGET_OS_IS_GPU TRUE)
 elseif(LIBC_TARGET_OS STREQUAL "uefi")
--- a/libc/config/freebsd/x86_64/entrypoints.txt
+++ b/libc/config/freebsd/x86_64/entrypoints.txt
@ -0,0 +1,656 @@
+set(TARGET_LIBC_ENTRYPOINTS
+    # ctype.h entrypoints
+    libc.src.ctype.isalnum
+    libc.src.ctype.isalpha
+    libc.src.ctype.isascii
+    libc.src.ctype.isblank
+    libc.src.ctype.iscntrl
+    libc.src.ctype.isdigit
+    libc.src.ctype.isgraph
+    libc.src.ctype.islower
+    libc.src.ctype.isprint
+    libc.src.ctype.ispunct
+    libc.src.ctype.isspace
+    libc.src.ctype.isupper
+    libc.src.ctype.isxdigit
+    libc.src.ctype.toascii
+    libc.src.ctype.tolower
+    libc.src.ctype.toupper
+
+    # string.h entrypoints
+    libc.src.string.memccpy
+    libc.src.string.memchr
+    libc.src.string.memcmp
+    libc.src.string.memcpy
+    libc.src.string.memmem
+    libc.src.string.memmove
+    libc.src.string.mempcpy
+    libc.src.string.memrchr
+    libc.src.string.memset
+    libc.src.string.stpcpy
+    libc.src.string.stpncpy
+    libc.src.string.strcasestr
+    libc.src.string.strcat
+    libc.src.string.strchr
+    libc.src.string.strchrnul
+    libc.src.string.strcmp
+    libc.src.string.strcpy
+    libc.src.string.strcspn
+    libc.src.string.strlcat
+    libc.src.string.strlcpy
+    libc.src.string.strlen
+    libc.src.string.strncat
+    libc.src.string.strncmp
+    libc.src.string.strncpy
+    libc.src.string.strnlen
+    libc.src.string.strpbrk
+    libc.src.string.strrchr
+    libc.src.string.strspn
+    libc.src.string.strstr
+    libc.src.string.strtok
+    libc.src.string.strtok_r
+
+    # string.h entrypoints that depend on malloc
+    libc.src.string.strdup
+    libc.src.string.strndup
+
+    # strings.h entrypoints
+    libc.src.strings.bcmp
+    libc.src.strings.bcopy
+    libc.src.strings.bzero
+    libc.src.strings.strcasecmp
+    libc.src.strings.strncasecmp
+
+    # inttypes.h entrypoints
+    libc.src.inttypes.imaxabs
+    libc.src.inttypes.imaxdiv
+    libc.src.inttypes.strtoimax
+    libc.src.inttypes.strtoumax
+
+    # stdlib.h entrypoints
+    libc.src.stdlib.abs
+    libc.src.stdlib.atoi
+    libc.src.stdlib.atof
+    libc.src.stdlib.atol
+    libc.src.stdlib.atoll
+    libc.src.stdlib.bsearch
+    libc.src.stdlib.div
+    libc.src.stdlib.labs
+    libc.src.stdlib.ldiv
+    libc.src.stdlib.llabs
+    libc.src.stdlib.lldiv
+    libc.src.stdlib.qsort
+    libc.src.stdlib.strtod
+    libc.src.stdlib.strtof
+    libc.src.stdlib.strtol
+    libc.src.stdlib.strtold
+    libc.src.stdlib.strtoll
+    libc.src.stdlib.strtoul
+    libc.src.stdlib.strtoull
+
+    # stdlib.h external entrypoints
+    libc.src.stdlib.malloc
+    libc.src.stdlib.calloc
+    libc.src.stdlib.realloc
+    libc.src.stdlib.aligned_alloc
+    libc.src.stdlib.free
+
+    # errno.h entrypoints
+    libc.src.errno.errno
+)
+
+set(TARGET_LIBM_ENTRYPOINTS
+    # fenv.h entrypoints
+    libc.src.fenv.feclearexcept
+    libc.src.fenv.fedisableexcept
+    libc.src.fenv.feenableexcept
+    libc.src.fenv.fegetenv
+    libc.src.fenv.fegetexcept
+    libc.src.fenv.fegetexceptflag
+    libc.src.fenv.fegetround
+    libc.src.fenv.feholdexcept
+    libc.src.fenv.fesetenv
+    libc.src.fenv.fesetexcept
+    libc.src.fenv.fesetexceptflag
+    libc.src.fenv.fesetround
+    libc.src.fenv.feraiseexcept
+    libc.src.fenv.fetestexcept
+    libc.src.fenv.fetestexceptflag
+    libc.src.fenv.feupdateenv
+
+    # math.h entrypoints
+    libc.src.math.acosf
+    libc.src.math.acoshf
+    libc.src.math.asinf
+    libc.src.math.asinhf
+    libc.src.math.atan2
+    libc.src.math.atan2f
+    libc.src.math.atanf
+    libc.src.math.atanhf
+    libc.src.math.cbrt
+    libc.src.math.cbrtf
+    libc.src.math.copysign
+    libc.src.math.copysignf
+    libc.src.math.copysignl
+    libc.src.math.ceil
+    libc.src.math.ceilf
+    libc.src.math.ceill
+    libc.src.math.cos
+    libc.src.math.cosf
+    libc.src.math.coshf
+    libc.src.math.daddl
+    libc.src.math.ddivl
+    libc.src.math.dfmal
+    libc.src.math.dsubl
+    libc.src.math.erff
+    libc.src.math.exp
+    libc.src.math.expf
+    libc.src.math.exp10
+    libc.src.math.exp10f
+    libc.src.math.exp2
+    libc.src.math.exp2f
+    libc.src.math.expm1
+    libc.src.math.expm1f
+    libc.src.math.fabs
+    libc.src.math.fabsf
+    libc.src.math.fabsl
+    libc.src.math.fadd
+    libc.src.math.faddl
+    libc.src.math.fdim
+    libc.src.math.fdimf
+    libc.src.math.fdiml
+    libc.src.math.fdiv
+    libc.src.math.fdivl
+    libc.src.math.ffma
+    libc.src.math.ffmal
+    libc.src.math.floor
+    libc.src.math.floorf
+    libc.src.math.floorl
+    libc.src.math.fma
+    libc.src.math.fmaf
+    libc.src.math.fmin
+    libc.src.math.fminf
+    libc.src.math.fminl
+    libc.src.math.fmax
+    libc.src.math.fmaxf
+    libc.src.math.fmaxl
+    libc.src.math.fmaximum
+    libc.src.math.fmaximumf
+    libc.src.math.fmaximuml
+    libc.src.math.fmaximum_num
+    libc.src.math.fmaximum_numf
+    libc.src.math.fmaximum_numl
+    libc.src.math.fmaximum_mag
+    libc.src.math.fmaximum_magf
+    libc.src.math.fmaximum_magl
+    libc.src.math.fmaximum_mag_num
+    libc.src.math.fmaximum_mag_numf
+    libc.src.math.fmaximum_mag_numl
+    libc.src.math.fminimum
+    libc.src.math.fminimumf
+    libc.src.math.fminimuml
+    libc.src.math.fminimum_num
+    libc.src.math.fminimum_numf
+    libc.src.math.fminimum_numl
+    libc.src.math.fminimum_mag
+    libc.src.math.fminimum_magf
+    libc.src.math.fminimum_magl
+    libc.src.math.fminimum_mag_num
+    libc.src.math.fminimum_mag_numf
+    libc.src.math.fminimum_mag_numl
+    libc.src.math.fmul
+    libc.src.math.fmod
+    libc.src.math.fmodf
+    libc.src.math.fmodl
+    libc.src.math.frexp
+    libc.src.math.frexpf
+    libc.src.math.frexpl
+    libc.src.math.fsub
+    libc.src.math.fsubl
+    libc.src.math.hypot
+    libc.src.math.hypotf
+    libc.src.math.ilogb
+    libc.src.math.ilogbf
+    libc.src.math.ilogbl
+    libc.src.math.ldexp
+    libc.src.math.ldexpf
+    libc.src.math.ldexpl
+    libc.src.math.llrint
+    libc.src.math.llrintf
+    libc.src.math.llrintl
+    libc.src.math.llround
+    libc.src.math.llroundf
+    libc.src.math.llroundl
+    libc.src.math.log10
+    libc.src.math.log10f
+    libc.src.math.log1p
+    libc.src.math.log1pf
+    libc.src.math.log2
+    libc.src.math.log2f
+    libc.src.math.log
+    libc.src.math.logf
+    libc.src.math.logb
+    libc.src.math.logbf
+    libc.src.math.logbl
+    libc.src.math.lrint
+    libc.src.math.lrintf
+    libc.src.math.lrintl
+    libc.src.math.lround
+    libc.src.math.lroundf
+    libc.src.math.lroundl
+    libc.src.math.modf
+    libc.src.math.modff
+    libc.src.math.modfl
+    libc.src.math.nan
+    libc.src.math.nanf
+    libc.src.math.nanl
+    libc.src.math.nearbyint
+    libc.src.math.nearbyintf
+    libc.src.math.nearbyintl
+    libc.src.math.nextafter
+    libc.src.math.nextafterf
+    libc.src.math.nextafterl
+    libc.src.math.nexttoward
+    libc.src.math.nexttowardf
+    libc.src.math.nexttowardl
+    libc.src.math.pow
+    libc.src.math.powf
+    libc.src.math.remainderf
+    libc.src.math.remainder
+    libc.src.math.remainderl
+    libc.src.math.remquof
+    libc.src.math.remquo
+    libc.src.math.remquol
+    libc.src.math.rint
+    libc.src.math.rintf
+    libc.src.math.rintl
+    libc.src.math.round
+    libc.src.math.roundf
+    libc.src.math.roundl
+    libc.src.math.scalbln
+    libc.src.math.scalblnf
+    libc.src.math.scalblnl
+    libc.src.math.scalbn
+    libc.src.math.scalbnf
+    libc.src.math.scalbnl
+    libc.src.math.sin
+    libc.src.math.sincosf
+    libc.src.math.sincosf
+    libc.src.math.sinf
+    libc.src.math.sinhf
+    libc.src.math.sqrt
+    libc.src.math.sqrtf
+    libc.src.math.sqrtl
+    libc.src.math.tan
+    libc.src.math.tanf
+    libc.src.math.tanhf
+    libc.src.math.trunc
+    libc.src.math.truncf
+    libc.src.math.truncl
+)
+
+list(APPEND TARGET_LIBM_ENTRYPOINTS
+    libc.src.math.acos
+    libc.src.math.acospif
+    libc.src.math.asin
+    libc.src.math.asinpi
+    libc.src.math.asinpif
+    libc.src.math.atan
+    libc.src.math.canonicalize
+    libc.src.math.canonicalizef
+    libc.src.math.canonicalizel
+    libc.src.math.cbrtbf16
+    libc.src.math.cospif
+    libc.src.math.dmull
+    libc.src.math.dsqrtl
+    libc.src.math.exp10m1f
+    libc.src.math.exp2m1f
+    libc.src.math.fmabf16
+    libc.src.math.fmull
+    libc.src.math.fromfp
+    libc.src.math.fromfpf
+    libc.src.math.fromfpl
+    libc.src.math.fromfpx
+    libc.src.math.fromfpxf
+    libc.src.math.fromfpxl
+    libc.src.math.fsqrt
+    libc.src.math.fsqrtl
+    libc.src.math.getpayload
+    libc.src.math.getpayloadf
+    libc.src.math.getpayloadl
+    libc.src.math.iscanonical
+    libc.src.math.iscanonicalf
+    libc.src.math.iscanonicall
+    libc.src.math.isnan
+    libc.src.math.isnanf
+    libc.src.math.isnanl
+    libc.src.math.issignaling
+    libc.src.math.issignalingf
+    libc.src.math.issignalingl
+    libc.src.math.llogb
+    libc.src.math.llogbf
+    libc.src.math.llogbl
+    libc.src.math.nextdown
+    libc.src.math.nextdownf
+    libc.src.math.nextdownl
+    libc.src.math.nextup
+    libc.src.math.nextupf
+    libc.src.math.nextupl
+    libc.src.math.roundeven
+    libc.src.math.roundevenf
+    libc.src.math.roundevenl
+    libc.src.math.setpayload
+    libc.src.math.setpayloadf
+    libc.src.math.setpayloadl
+    libc.src.math.setpayloadsig
+    libc.src.math.setpayloadsigf
+    libc.src.math.setpayloadsigl
+    libc.src.math.sincos
+    libc.src.math.sinpif
+    libc.src.math.tanpif
+    libc.src.math.totalorder
+    libc.src.math.totalorderf
+    libc.src.math.totalorderl
+    libc.src.math.totalordermag
+    libc.src.math.totalordermagf
+    libc.src.math.totalordermagl
+    libc.src.math.ufromfp
+    libc.src.math.ufromfpf
+    libc.src.math.ufromfpl
+    libc.src.math.ufromfpx
+    libc.src.math.ufromfpxf
+    libc.src.math.ufromfpxl
+)
+
+if(LIBC_TYPES_HAS_FLOAT16)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    libc.src.math.acosf16
+    libc.src.math.acoshf16
+    libc.src.math.acospif16
+    libc.src.math.asinf16
+    libc.src.math.asinhf16
+    libc.src.math.asinpif16
+    libc.src.math.atanf16
+    libc.src.math.atan2f16
+    libc.src.math.atanhf16
+    libc.src.math.atanpif16
+    libc.src.math.canonicalizef16
+    libc.src.math.ceilf16
+    libc.src.math.copysignf16
+    libc.src.math.cosf16
+    libc.src.math.coshf16
+    libc.src.math.cospif16
+    libc.src.math.erff16
+    libc.src.math.erfcf16
+    libc.src.math.exp10f16
+    libc.src.math.exp10m1f16
+    libc.src.math.exp2f16
+    libc.src.math.exp2m1f16
+    libc.src.math.expf16
+    libc.src.math.expm1f16
+    libc.src.math.f16add
+    libc.src.math.f16addf
+    libc.src.math.f16addl
+    libc.src.math.f16div
+    libc.src.math.f16divf
+    libc.src.math.f16divl
+    libc.src.math.f16fma
+    libc.src.math.f16fmaf
+    libc.src.math.f16fmal
+    libc.src.math.f16mul
+    libc.src.math.f16mulf
+    libc.src.math.f16mull
+    libc.src.math.f16sqrt
+    libc.src.math.f16sqrtf
+    libc.src.math.f16sqrtl
+    libc.src.math.f16sub
+    libc.src.math.f16subf
+    libc.src.math.f16subl
+    libc.src.math.fabsf16
+    libc.src.math.fdimf16
+    libc.src.math.floorf16
+    libc.src.math.fmaf16
+    libc.src.math.fmaxf16
+    libc.src.math.fmaximum_mag_numf16
+    libc.src.math.fmaximum_magf16
+    libc.src.math.fmaximum_numf16
+    libc.src.math.fmaximumf16
+    libc.src.math.fminf16
+    libc.src.math.fminimum_mag_numf16
+    libc.src.math.fminimum_magf16
+    libc.src.math.fminimum_numf16
+    libc.src.math.fminimumf16
+    libc.src.math.fmodf16
+    libc.src.math.frexpf16
+    libc.src.math.fromfpf16
+    libc.src.math.fromfpxf16
+    libc.src.math.getpayloadf16
+    libc.src.math.hypotf16
+    libc.src.math.ilogbf16
+    libc.src.math.iscanonicalf16
+    libc.src.math.issignalingf16
+    libc.src.math.ldexpf16
+    libc.src.math.llogbf16
+    libc.src.math.llrintf16
+    libc.src.math.llroundf16
+    libc.src.math.log10f16
+    libc.src.math.log10p1f16
+    libc.src.math.log2f16
+    libc.src.math.log2p1f16
+    libc.src.math.logbf16
+    libc.src.math.logf16
+    libc.src.math.lrintf16
+    libc.src.math.lroundf16
+    libc.src.math.modff16
+    libc.src.math.nanf16
+    libc.src.math.nearbyintf16
+    libc.src.math.nextafterf16
+    libc.src.math.nextdownf16
+    libc.src.math.nexttowardf16
+    libc.src.math.nextupf16
+    libc.src.math.remainderf16
+    libc.src.math.remquof16
+    libc.src.math.rintf16
+    libc.src.math.roundevenf16
+    libc.src.math.roundf16
+    libc.src.math.rsqrtf
+    libc.src.math.rsqrtf16
+    libc.src.math.scalblnf16
+    libc.src.math.scalbnf16
+    libc.src.math.setpayloadf16
+    libc.src.math.setpayloadsigf16
+    libc.src.math.sinf16
+    libc.src.math.sinhf16
+    libc.src.math.sinpif16
+    libc.src.math.sqrtf16
+    libc.src.math.tanf16
+    libc.src.math.tanhf16
+    libc.src.math.tanpif16
+    libc.src.math.totalorderf16
+    libc.src.math.totalordermagf16
+    libc.src.math.truncf16
+    libc.src.math.ufromfpf16
+    libc.src.math.ufromfpxf16
+  )
+
+  if(LIBC_TYPES_HAS_FLOAT128)
+    list(APPEND TARGET_LIBM_ENTRYPOINTS
+      libc.src.math.f16addf128
+      libc.src.math.f16divf128
+      libc.src.math.f16fmaf128
+      libc.src.math.f16mulf128
+      libc.src.math.f16sqrtf128
+      libc.src.math.f16subf128
+    )
+  endif()
+endif()
+
+if(LIBC_TYPES_HAS_FLOAT128)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    libc.src.math.atan2f128
+    libc.src.math.atan2l
+    libc.src.math.canonicalizef128
+    libc.src.math.ceilf128
+    libc.src.math.copysignf128
+    libc.src.math.daddf128
+    libc.src.math.ddivf128
+    libc.src.math.dfmaf128
+    libc.src.math.dmulf128
+    libc.src.math.dsqrtf128
+    libc.src.math.dsubf128
+    libc.src.math.fabsf128
+    libc.src.math.faddf128
+    libc.src.math.fdimf128
+    libc.src.math.fdivf128
+    libc.src.math.ffmaf128
+    libc.src.math.floorf128
+    libc.src.math.fmaxf128
+    libc.src.math.fmaximum_mag_numf128
+    libc.src.math.fmaximum_magf128
+    libc.src.math.fmaximum_numf128
+    libc.src.math.fmaximumf128
+    libc.src.math.fminf128
+    libc.src.math.fminimum_mag_numf128
+    libc.src.math.fminimum_magf128
+    libc.src.math.fminimum_numf128
+    libc.src.math.fminimumf128
+    libc.src.math.fmodf128
+    libc.src.math.fmulf128
+    libc.src.math.frexpf128
+    libc.src.math.fromfpf128
+    libc.src.math.fromfpxf128
+    libc.src.math.fsqrtf128
+    libc.src.math.fsubf128
+    libc.src.math.getpayloadf128
+    libc.src.math.ilogbf128
+    libc.src.math.iscanonicalf128
+    libc.src.math.issignalingf128
+    libc.src.math.ldexpf128
+    libc.src.math.llogbf128
+    libc.src.math.llrintf128
+    libc.src.math.llroundf128
+    libc.src.math.logbf128
+    libc.src.math.lrintf128
+    libc.src.math.lroundf128
+    libc.src.math.modff128
+    libc.src.math.nanf128
+    libc.src.math.nearbyintf128
+    libc.src.math.nextafterf128
+    libc.src.math.nextdownf128
+    libc.src.math.nextupf128
+    libc.src.math.remainderf128
+    libc.src.math.remquof128
+    libc.src.math.rintf128
+    libc.src.math.roundevenf128
+    libc.src.math.roundf128
+    libc.src.math.scalblnf128
+    libc.src.math.scalbnf128
+    libc.src.math.setpayloadf128
+    libc.src.math.setpayloadsigf128
+    libc.src.math.sqrtf128
+    libc.src.math.totalorderf128
+    libc.src.math.totalordermagf128
+    libc.src.math.truncf128
+    libc.src.math.ufromfpf128
+    libc.src.math.ufromfpxf128
+  )
+endif()
+
+list(APPEND TARGET_LIBM_ENTRYPOINTS
+  libc.src.math.atanbf16
+  libc.src.math.asinbf16
+  libc.src.math.bf16add
+  libc.src.math.bf16addf
+  libc.src.math.bf16addl
+  libc.src.math.bf16div
+  libc.src.math.bf16divf
+  libc.src.math.bf16divl
+  libc.src.math.bf16fma
+  libc.src.math.bf16fmaf
+  libc.src.math.bf16fmal
+  libc.src.math.bf16mul
+  libc.src.math.bf16mulf
+  libc.src.math.bf16mull
+  libc.src.math.bf16sub
+  libc.src.math.bf16subf
+  libc.src.math.bf16subl
+  libc.src.math.canonicalizebf16
+  libc.src.math.ceilbf16
+  libc.src.math.copysignbf16
+  libc.src.math.fabsbf16
+  libc.src.math.fdimbf16
+  libc.src.math.floorbf16
+  libc.src.math.fmaxbf16
+  libc.src.math.fmaximumbf16
+  libc.src.math.fmaximum_magbf16
+  libc.src.math.fmaximum_mag_numbf16
+  libc.src.math.fmaximum_numbf16
+  libc.src.math.fminbf16
+  libc.src.math.fminimumbf16
+  libc.src.math.fminimum_magbf16
+  libc.src.math.fminimum_mag_numbf16
+  libc.src.math.fminimum_numbf16
+  libc.src.math.fmodbf16
+  libc.src.math.frexpbf16
+  libc.src.math.fromfpbf16
+  libc.src.math.fromfpxbf16
+  libc.src.math.getpayloadbf16
+  libc.src.math.hypotbf16
+  libc.src.math.ilogbbf16
+  libc.src.math.iscanonicalbf16
+  libc.src.math.issignalingbf16
+  libc.src.math.ldexpbf16
+  libc.src.math.llogbbf16
+  libc.src.math.llrintbf16
+  libc.src.math.llroundbf16
+  libc.src.math.log_bf16
+  libc.src.math.logbbf16
+  libc.src.math.lrintbf16
+  libc.src.math.lroundbf16
+  libc.src.math.modfbf16
+  libc.src.math.nanbf16
+  libc.src.math.nearbyintbf16
+  libc.src.math.nextafterbf16
+  libc.src.math.nextdownbf16
+  libc.src.math.nexttowardbf16
+  libc.src.math.nextupbf16
+  libc.src.math.remainderbf16
+  libc.src.math.remquobf16
+  libc.src.math.rintbf16
+  libc.src.math.roundbf16
+  libc.src.math.roundevenbf16
+  libc.src.math.scalblnbf16
+  libc.src.math.scalbnbf16
+  libc.src.math.setpayloadbf16
+  libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
+  libc.src.math.truncbf16
+  libc.src.math.totalorderbf16
+  libc.src.math.totalordermagbf16
+  libc.src.math.ufromfpbf16
+  libc.src.math.ufromfpxbf16
+)
+
+if(LIBC_TYPES_HAS_FLOAT128)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    libc.src.math.bf16addf128
+    libc.src.math.bf16divf128
+    libc.src.math.bf16fmaf128
+    libc.src.math.bf16mulf128
+    libc.src.math.bf16subf128
+  )
+endif()
+
+set(TARGET_LIBMVEC_ENTRYPOINTS)
+
+if(LIBC_COMPILER_HAS_EXT_VECTOR_TYPE)
+  list(APPEND TARGET_LIBMVEC_ENTRYPOINTS
+    libc.src.mathvec.expf
+  )
+endif()
+
+set(TARGET_LLVMLIBC_ENTRYPOINTS
+  ${TARGET_LIBC_ENTRYPOINTS}
+  ${TARGET_LIBM_ENTRYPOINTS}
+  ${TARGET_LIBMVEC_ENTRYPOINTS}
+)
--- a/libc/config/freebsd/x86_64/headers.txt
+++ b/libc/config/freebsd/x86_64/headers.txt
@ -0,0 +1,9 @@
+set(TARGET_PUBLIC_HEADERS
+    libc.include.ctype
+    libc.include.string
+    libc.include.inttypes
+    libc.include.stdlib
+    libc.include.errno
+    libc.include.fenv
+    libc.include.math
+)
--- a/libc/src/__support/CPP/tuple.h
+++ b/libc/src/__support/CPP/tuple.h
@ -1,10 +1,15 @@
-//===-- tuple utility -------------------------------------------*- C++ -*-===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// Tuple utility.
+///
+//===----------------------------------------------------------------------===//

 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_TUPLE_H
 #define LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_TUPLE_H
@ -125,7 +130,12 @@ LIBC_INLINE constexpr auto tuple_cat(const Tuples &...tuples) {
 } // namespace LIBC_NAMESPACE_DECL

 // Standard namespace definitions required for structured binding support.
+
+#ifdef _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_NAMESPACE_STD
+#else
 namespace std {
+#endif

 template <class T> struct tuple_size;
 template <size_t Idx, class T> struct tuple_element;
@ -139,6 +149,10 @@ struct tuple_element<Idx, LIBC_NAMESPACE::cpp::tuple<Ts...>>
    : LIBC_NAMESPACE::cpp::tuple_element<Idx,
                                         LIBC_NAMESPACE::cpp::tuple<Ts...>> {};

+#ifdef _LIBCPP_END_NAMESPACE_STD
+_LIBCPP_END_NAMESPACE_STD
+#else
 } // namespace std
+#endif

 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_TUPLE_H
--- a/libc/src/__support/OSUtil/freebsd/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/freebsd/CMakeLists.txt
@ -0,0 +1,18 @@
+if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
+  return()
+endif()
+
+add_subdirectory(${LIBC_TARGET_ARCHITECTURE})
+add_subdirectory(syscall_wrappers)
+
+add_object_library(
+  freebsd_util
+  SRCS
+    exit.cpp
+  HDRS
+    io.h
+  DEPENDS
+    .${LIBC_TARGET_ARCHITECTURE}.freebsd_${LIBC_TARGET_ARCHITECTURE}_util
+    libc.src.__support.OSUtil.freebsd.syscall_wrappers.write
+    libc.src.__support.macros.config
+)
--- a/libc/src/__support/OSUtil/freebsd/exit.cpp
+++ b/libc/src/__support/OSUtil/freebsd/exit.cpp
@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// FreeBSD implementation of an exit function.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
+
+// mark as no_stack_protector for x86 since TLS can be torn down before calling
+// exit so that the stack protector canary cannot be loaded.
+#ifdef LIBC_TARGET_ARCH_IS_X86
+__attribute__((no_stack_protector))
+#endif
+__attribute__((noreturn)) void exit(int status) {
+  for (;;)
+    syscall_impl(SYS_exit, status);
+}
+
+} // namespace internal
+} // namespace LIBC_NAMESPACE_DECL
--- a/libc/src/__support/OSUtil/freebsd/io.h
+++ b/libc/src/__support/OSUtil/freebsd/io.h
@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// FreeBSD implementation of IO utils.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_IO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_IO_H
+
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/OSUtil/freebsd/syscall_wrappers/write.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+LIBC_INLINE void write_to_stderr(cpp::string_view msg) {
+  freebsd_syscalls::write(2 /* stderr */, msg.data(), msg.size());
+}
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_IO_H
--- a/libc/src/__support/OSUtil/freebsd/syscall.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall.h
@ -0,0 +1,52 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// FreeBSD syscalls.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_H
+
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/architectures.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+struct SyscallReturn {
+  long value;
+  bool is_error;
+};
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#ifdef LIBC_TARGET_ARCH_IS_X86_32
+#include "i386/syscall.h"
+#elif defined(LIBC_TARGET_ARCH_IS_X86_64)
+#include "x86_64/syscall.h"
+#elif defined(LIBC_TARGET_ARCH_IS_AARCH64)
+#include "aarch64/syscall.h"
+#elif defined(LIBC_TARGET_ARCH_IS_ARM)
+#include "arm/syscall.h"
+#elif defined(LIBC_TARGET_ARCH_IS_ANY_RISCV)
+#include "riscv/syscall.h"
+#endif
+
+namespace LIBC_NAMESPACE_DECL {
+
+template <typename... Ts>
+LIBC_INLINE SyscallReturn syscall_impl(long __number, Ts... ts) {
+  static_assert(sizeof...(Ts) <= 6, "Too many arguments for syscall");
+  return syscall_impl(__number, (long)ts...);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/CMakeLists.txt
@ -0,0 +1,92 @@
+add_header_library(
+  close
+  HDRS
+    close.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  getrandom
+  HDRS
+    getrandom.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.hdr.types.ssize_t
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  mmap
+  HDRS
+    mmap.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.hdr.types.off_t
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  mprotect
+  HDRS
+    mprotect.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  munmap
+  HDRS
+    munmap.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  open
+  HDRS
+    open.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.hdr.types.mode_t
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  read
+  HDRS
+    read.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.hdr.types.ssize_t
+    libc.include.sys_syscall
+)
+
+add_header_library(
+  write
+  HDRS
+    write.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.error_or
+    libc.src.__support.macros.config
+    libc.hdr.types.ssize_t
+    libc.include.sys_syscall
+)
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/close.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/close.h
@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for close.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_CLOSE_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_CLOSE_H
+
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<int> close(int fd) {
+  SyscallReturn ret = syscall_impl(SYS_close, fd);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<int>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_CLOSE_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/getrandom.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/getrandom.h
@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for getrandom.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_GETRANDOM_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_GETRANDOM_H
+
+#include "hdr/types/ssize_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<ssize_t> getrandom(void *buf, size_t buflen,
+                                       unsigned int flags) {
+  SyscallReturn ret = syscall_impl(SYS_getrandom, buf, buflen, flags);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<ssize_t>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_GETRANDOM_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/mmap.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/mmap.h
@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for mmap.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MMAP_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MMAP_H
+
+#include "hdr/types/off_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<void *> mmap(void *addr, size_t size, int prot, int flags,
+                                 int fd, off_t offset) {
+  SyscallReturn ret = syscall_impl(SYS_mmap, reinterpret_cast<long>(addr), size,
+                                   prot, flags, fd, static_cast<long>(offset));
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return reinterpret_cast<void *>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MMAP_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/mprotect.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/mprotect.h
@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for mprotect.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MPROTECT_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MPROTECT_H
+
+#include "hdr/types/size_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<int> mprotect(void *addr, size_t size, int prot) {
+  SyscallReturn ret =
+      syscall_impl(SYS_mprotect, reinterpret_cast<long>(addr), size, prot);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<int>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MPROTECT_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/munmap.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/munmap.h
@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for munmap.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MUNMAP_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MUNMAP_H
+
+#include "hdr/types/size_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<int> munmap(void *addr, size_t size) {
+  SyscallReturn ret =
+      syscall_impl(SYS_munmap, reinterpret_cast<long>(addr), size);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<int>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_MUNMAP_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/open.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/open.h
@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for open.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_OPEN_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_OPEN_H
+
+#include "hdr/types/mode_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<int> open(const char *path, int flags, mode_t mode_flags) {
+  SyscallReturn ret = syscall_impl(SYS_open, path, flags, mode_flags);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<int>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_OPEN_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/read.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/read.h
@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for read.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_READ_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_READ_H
+
+#include "hdr/types/ssize_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<ssize_t> read(int fd, void *buf, size_t count) {
+  SyscallReturn ret = syscall_impl(SYS_read, fd, buf, count);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<ssize_t>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_READ_H
--- a/libc/src/__support/OSUtil/freebsd/syscall_wrappers/write.h
+++ b/libc/src/__support/OSUtil/freebsd/syscall_wrappers/write.h
@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation header for write.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_WRITE_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_WRITE_H
+
+#include "hdr/types/ssize_t.h"
+#include "src/__support/OSUtil/freebsd/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace freebsd_syscalls {
+
+LIBC_INLINE ErrorOr<ssize_t> write(int fd, const void *buf, size_t count) {
+  SyscallReturn ret = syscall_impl(SYS_write, fd, buf, count);
+  if (ret.is_error)
+    return Error(static_cast<int>(ret.value));
+  return static_cast<ssize_t>(ret.value);
+}
+
+} // namespace freebsd_syscalls
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_SYSCALL_WRAPPERS_WRITE_H
--- a/libc/src/__support/OSUtil/freebsd/x86_64/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/freebsd/x86_64/CMakeLists.txt
@ -0,0 +1,7 @@
+add_header_library(
+  freebsd_x86_64_util
+  HDRS
+    syscall.h
+  DEPENDS
+    libc.src.__support.common
+)
--- a/libc/src/__support/OSUtil/freebsd/x86_64/syscall.h
+++ b/libc/src/__support/OSUtil/freebsd/x86_64/syscall.h
@ -0,0 +1,118 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Inline implementation of x86_64 syscalls.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_X86_64_SYSCALL_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_X86_64_SYSCALL_H
+
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+#define SYSCALL_CLOBBER_LIST "rcx", "r11", "memory", "cc"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number) {
+  long retcode;
+  bool is_error;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1) {
+  long retcode;
+  bool is_error;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1,
+                                       long __arg2) {
+  long retcode;
+  bool is_error;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1), "S"(__arg2)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1, long __arg2,
+                                       long __arg3) {
+  long retcode;
+  bool is_error;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1, long __arg2,
+                                       long __arg3, long __arg4) {
+  long retcode;
+  bool is_error;
+  register long r10 __asm__("r10") = __arg4;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1, long __arg2,
+                                       long __arg3, long __arg4, long __arg5) {
+  long retcode;
+  bool is_error;
+  register long r10 __asm__("r10") = __arg4;
+  register long r8 __asm__("r8") = __arg5;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10),
+                 "r"(r8)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+LIBC_INLINE SyscallReturn syscall_impl(long __number, long __arg1, long __arg2,
+                                       long __arg3, long __arg4, long __arg5,
+                                       long __arg6) {
+  long retcode;
+  bool is_error;
+  register long r10 __asm__("r10") = __arg4;
+  register long r8 __asm__("r8") = __arg5;
+  register long r9 __asm__("r9") = __arg6;
+  asm volatile("syscall\n\t"
+               "setc %1"
+               : "=a"(retcode), "=qm"(is_error)
+               : "a"(__number), "D"(__arg1), "S"(__arg2), "d"(__arg3), "r"(r10),
+                 "r"(r8), "r"(r9)
+               : SYSCALL_CLOBBER_LIST);
+  return {retcode, is_error};
+}
+
+#undef SYSCALL_CLOBBER_LIST
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FREEBSD_X86_64_SYSCALL_H
--- a/libc/src/__support/OSUtil/io.h
+++ b/libc/src/__support/OSUtil/io.h
@ -1,10 +1,15 @@
-//===---------------- Implementation of IO utils ----------------*- C++ -*-===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// Implementation of IO utils.
+///
+//===----------------------------------------------------------------------===//

 #ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_IO_H
 #define LLVM_LIBC_SRC___SUPPORT_OSUTIL_IO_H
@ -21,6 +26,8 @@
 #include "fuchsia/io.h"
 #elif defined(_WIN32)
 #include "windows/io.h"
+#elif defined(__FreeBSD__)
+#include "freebsd/io.h"
 #elif defined(__ELF__)
 // TODO: Ideally we would have LIBC_TARGET_OS_IS_BAREMETAL.
 #include "baremetal/io.h"
--- a/libc/src/__support/OSUtil/syscall.h
+++ b/libc/src/__support/OSUtil/syscall.h
@ -1,10 +1,15 @@
-//===--------------- Internal syscall declarations --------------*- C++ -*-===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// Internal syscall declarations.
+///
+//===----------------------------------------------------------------------===//

 #ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_H
 #define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_H
@ -13,6 +18,8 @@
 #include "darwin/syscall.h"
 #elif defined(__linux__)
 #include "linux/syscall.h"
+#elif defined(__FreeBSD__)
+#include "freebsd/syscall.h"
 #endif

 #endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_H
--- a/libc/test/UnitTest/FPExceptMatcher.cpp
+++ b/libc/test/UnitTest/FPExceptMatcher.cpp
@ -1,10 +1,15 @@
-//===-- FPExceptMatchers.cpp ----------------------------------------------===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// FPExceptMatchers.cpp.
+///
+//===----------------------------------------------------------------------===//

 #undef LIBC_MATH_USE_SYSTEM_FENV

@ -30,6 +35,10 @@ namespace testing {
 #define siglongjmp(buf, val) longjmp(buf, val)
 #endif

+#ifdef __FreeBSD__
+using sighandler_t = __sighandler_t *;
+#endif
+
 static thread_local sigjmp_buf jumpBuffer;
 static thread_local bool caughtExcept;

--- a/libc/test/src/CMakeLists.txt
+++ b/libc/test/src/CMakeLists.txt
@ -34,8 +34,8 @@ function(add_fp_unittest name)
    endif()
    set(test_type UNIT_TEST_ONLY)
    list(APPEND MATH_UNITTEST_LINK_LIBRARIES libcMPFRWrapper -lmpfr -lgmp)
-    if(NOT(LIBC_TARGET_OS_IS_DARWIN))
-      # macOS does not have libatomic.
+    if(NOT(LIBC_TARGET_OS_IS_DARWIN) AND NOT(LIBC_TARGET_OS_IS_FREEBSD))
+      # macOS/FreeBSD does not have libatomic.
      list(APPEND MATH_UNITTEST_LINK_LIBRARIES -latomic)
    endif()
  endif()
--- a/libc/test/src/math/FModTest.h
+++ b/libc/test/src/math/FModTest.h
@ -1,10 +1,15 @@
-//===-- Utility class to test fmod special numbers ------------------------===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// Utility class to test fmod special numbers.
+///
+//===----------------------------------------------------------------------===//

 #ifndef LLVM_LIBC_TEST_SRC_MATH_FMODTEST_H
 #define LLVM_LIBC_TEST_SRC_MATH_FMODTEST_H
@ -19,6 +24,8 @@

 #ifdef FE_DENORM
 #define DENORM_EXCEPT FE_DENORM
+#elif defined(FE_DENORMAL)
+#define DENORM_EXCEPT FE_DENORMAL
 #elif defined(__FE_DENORM)
 #define DENORM_EXCEPT __FE_DENORM
 #else
--- a/libc/test/src/math/smoke/FModTest.h
+++ b/libc/test/src/math/smoke/FModTest.h
@ -1,10 +1,15 @@
-//===-- Utility class to test fmod special numbers ------------------------===//
+//===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// Utility class to test fmod special numbers.
+///
+//===----------------------------------------------------------------------===//

 #ifndef LLVM_LIBC_TEST_SRC_MATH_FMODTEST_H
 #define LLVM_LIBC_TEST_SRC_MATH_FMODTEST_H
@ -20,6 +25,8 @@

 #ifdef FE_DENORM
 #define DENORM_EXCEPT FE_DENORM
+#elif defined(FE_DENORMAL)
+#define DENORM_EXCEPT FE_DENORMAL
 #elif defined(__FE_DENORM)
 #define DENORM_EXCEPT __FE_DENORM
 #else