diff --git a/WASI.cmake b/WASI.cmake
new file mode 100644
index 0000000..b49713f
--- /dev/null
+++ b/WASI.cmake
@@ -0,0 +1 @@
+set(WASI 1)
diff --git a/compiler-rt.spec b/compiler-rt.spec
index 08178ef..07b3afc 100644
--- a/compiler-rt.spec
+++ b/compiler-rt.spec
@@ -3,7 +3,7 @@
 %define majver %(echo %version | cut -d. -f1-2)
 Name:          compiler-rt
 Version:       18.1.8
-Release:       1mamba
+Release:       2mamba
 Summary:       Runtime libraries compiler for clang
 Group:         Development/Languages
 Vendor:        openmamba
@@ -12,12 +12,16 @@ Packager:      Silvan Calarco <silvan.calarco@mambasoft.it>
 URL:           https://llvm.org/
 Source0:       https://github.com/llvm/llvm-project/releases/download/llvmorg-%{version}/compiler-rt-%{version}.src.tar.xz
 Source1:       https://github.com/llvm/llvm-project/releases/download/llvmorg-%{version}/cmake-%{version}.src.tar.xz
+Source2:       https://github.com/llvm/llvm-project/releases/download/llvmorg-%{version}/llvm-%{version}.src.tar.xz
+Source10:      WASI.cmake
+Source11:      wasi-toolchain.cmake
 License:       NCSA
 ## AUTOBUILDREQ-BEGIN
 BuildRequires: glibc-devel
 BuildRequires: libgcc
 BuildRequires: libstdc++6-devel
 ## AUTOBUILDREQ-END
+BuildRequires: libwasi-libc-devel
 Requires(pre): clang
 
 %description
@@ -26,14 +30,38 @@ Runtime libraries compiler for clang.
 %debug_package
 
 %prep
-%setup -q -c -a0 -a1
+%setup -q -c -a0 -a1 -a2
 #-D -T
 #:<< _EOF
 mv compiler-rt-%{version}.src compiler-rt
 mv cmake-%{version}.src cmake
+mv llvm-%{version}.src llvm
+
+mkdir -p cmake/Platform
+cp %{SOURCE10} cmake/Platform
 
 %build
 #:<< __EOF
+mkdir -p build-wasi
+cd build-wasi
+cmake ../compiler-rt/lib/builtins -G Ninja \
+  -DCMAKE_BUILD_TYPE=Release \
+  -DCMAKE_C_COMPILER_WORKS=ON \
+  -DCMAKE_CXX_COMPILER_WORKS=ON \
+  -DCMAKE_MODULE_PATH="$PWD/../make" \
+  -DCMAKE_TOOLCHAIN_FILE="%{SOURCE11}" \
+  -DCOMPILER_RT_BAREMETAL_BUILD=On \
+  -DCOMPILER_RT_INCLUDE_TESTS=OFF \
+  -DCOMPILER_RT_HAS_FPIC_FLAG=OFF \
+  -DCOMPILER_RT_DEFAULT_TARGET_ONLY=On \
+  -DCOMPILER_RT_OS_DIR=wasi \
+  -DWASI_SDK_PREFIX=/usr \
+  -DCMAKE_C_FLAGS="-fno-exceptions --sysroot=%{_datadir}/wasi-sysroot" \
+  -DCMAKE_INSTALL_PREFIX=%{_libdir}/clang/%{MAJver}/ \
+
+ninja
+
+cd ..
 
 mkdir -p build
 cd build
@@ -51,8 +79,12 @@ ninja
 %install
 [ "%{buildroot}" != / ] && rm -rf "%{buildroot}"
 
-cd build
 export DESTDIR=%{buildroot}
+cd build-wasi
+ninja install
+cd ..
+
+cd build
 ninja install
 
 #mkdir -p %{buildroot}%{_libdir}/clang/%{MAJver}/{lib,share}
@@ -72,11 +104,16 @@ ninja install
 %{_libdir}/clang/%{MAJver}/include/*
 %dir %{_libdir}/clang/%{MAJver}/lib/linux
 %{_libdir}/clang/%{MAJver}/lib/linux/*
+%dir %{_libdir}/clang/%{MAJver}/lib/wasi
+%{_libdir}/clang/%{MAJver}/lib/wasi/libclang_rt.builtins-wasm32.a
 %dir %{_libdir}/clang/%{MAJver}/share
 %{_libdir}/clang/%{MAJver}/share/*.txt
 %doc compiler-rt/LICENSE.TXT
 
 %changelog
+* Sat Sep 14 2024 Silvan Calarco <silvan.calarco@mambasoft.it> 18.1.8-2mamba
+- rebuilt with wasi support
+
 * Sat Jun 22 2024 Automatic Build System <autodist@openmamba.org> 18.1.8-1mamba
 - automatic version update by autodist
 
diff --git a/wasi-toolchain.cmake b/wasi-toolchain.cmake
new file mode 100644
index 0000000..0920f76
--- /dev/null
+++ b/wasi-toolchain.cmake
@@ -0,0 +1,29 @@
+# Cmake toolchain description file for the Makefile
+
+# This is arbitrary, AFAIK, for now.
+cmake_minimum_required(VERSION 3.4.0)
+
+set(CMAKE_SYSTEM_NAME WASI)
+set(CMAKE_SYSTEM_VERSION 1)
+set(CMAKE_SYSTEM_PROCESSOR wasm32)
+set(triple wasm32-wasi)
+
+if(WIN32)
+  set(WASI_HOST_EXE_SUFFIX ".exe")
+else()
+  set(WASI_HOST_EXE_SUFFIX "")
+endif()
+
+set(CMAKE_C_COMPILER ${WASI_SDK_PREFIX}/bin/clang${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_CXX_COMPILER ${WASI_SDK_PREFIX}/bin/clang++${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_AR ${WASI_SDK_PREFIX}/bin/llvm-ar${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_RANLIB ${WASI_SDK_PREFIX}/bin/llvm-ranlib${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_C_COMPILER_TARGET ${triple})
+set(CMAKE_CXX_COMPILER_TARGET ${triple})
+
+# Don't look in the sysroot for executables to run during the build
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+# Only look in the sysroot (not in the host paths) for the rest
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)