diff --git a/c/Clang/Clang-17.0.3-GCCcore-12.2.0.eb b/c/Clang/Clang-17.0.3-GCCcore-12.2.0.eb
new file mode 100644
index 00000000..bd2017d1
--- /dev/null
+++ b/c/Clang/Clang-17.0.3-GCCcore-12.2.0.eb
@@ -0,0 +1,52 @@
+# IT4Innovations
+# LK 2023
+
+name = 'Clang'
+version = '17.0.3'
+
+homepage = 'https://clang.llvm.org/'
+description = """C, C++, Objective-C compiler, based on LLVM.  Does not
+ include C++ standard library -- use libstdc++ from GCC."""
+
+# Clang also depends on libstdc++ during runtime, but this dependency is
+# already specified as the toolchain.
+toolchain = {'name': 'GCCcore', 'version': '12.2.0'}
+
+source_urls = ["https://github.com/llvm/llvm-project/releases/download/llvmorg-%(version)s"]
+sources = [
+    'llvm-project-%(version)s.src.tar.xz',
+]
+checksums = [
+    {'llvm-project-17.0.3.src.tar.xz': 'be5a1e44d64f306bb44fce7d36e3b3993694e8e6122b2348608906283c176db8'},
+]
+
+builddependencies = [
+    ('CMake', '3.24.3'),
+    ('Perl', '5.36.0'),
+    # Including Python bindings would require this as a runtime dep
+    ('Python', '3.10.8'),
+]
+dependencies = [
+    # since Clang is a compiler, binutils is a runtime dependency too
+    ('binutils', '2.39'),
+    ('hwloc', '2.8.0'),
+    ('libxml2', '2.10.3'),
+    ('ncurses', '6.3'),
+    ('GMP', '6.2.1'),
+    ('Z3', '4.12.2'),
+]
+
+# enabling RTTI makes the flang compiler need to link to libc++ so instead of
+#   flang-new -flang-experimental-exec -fopenmp hello_openmp.f90
+# you would need
+#   flang-new -flang-experimental-exec -fopenmp hello_openmp.f90 -l c++
+enable_rtti = False
+
+assertions = True
+python_bindings = False
+skip_all_tests = True
+
+llvm_runtimes = ['libunwind', 'libcxx', 'libcxxabi']
+llvm_projects = ['polly', 'lld', 'lldb', 'clang-tools-extra', 'flang']
+
+moduleclass = 'compiler'
diff --git a/l/LLVM/LLVM-17.0.3-GCCcore-12.2.0.eb b/l/LLVM/LLVM-17.0.3-GCCcore-12.2.0.eb
new file mode 100644
index 00000000..23b34b9f
--- /dev/null
+++ b/l/LLVM/LLVM-17.0.3-GCCcore-12.2.0.eb
@@ -0,0 +1,51 @@
+# IT4Innovations
+# LK 2023
+
+name = 'LLVM'
+version = '17.0.3'
+
+homepage = "https://llvm.org/"
+description = """The LLVM Core libraries provide a modern source- and target-independent
+ optimizer, along with code generation support for many popular CPUs
+ (as well as some less common ones!) These libraries are built around a well
+ specified code representation known as the LLVM intermediate representation
+ ("LLVM IR"). The LLVM Core libraries are well documented, and it is
+ particularly easy to invent your own language (or port an existing compiler)
+ to use LLVM as an optimizer and code generator."""
+
+toolchain = {'name': 'GCCcore', 'version': '12.2.0'}
+toolchainopts = {'cstd': 'gnu++11', 'pic': True}
+
+source_urls = ['https://github.com/llvm/llvm-project/releases/download/llvmorg-%(version)s/']
+sources = [
+    'llvm-%(version)s.src.tar.xz',
+    'cmake-%(version)s.src.tar.xz',
+    'third-party-%(version)s.src.tar.xz',
+]
+checksums = [
+    {'llvm-17.0.3.src.tar.xz': '18fa6b5f172ddf5af9b3aedfdb58ba070fd07fc45e7e589c46c350b3cc066bc1'},
+    {'cmake-17.0.3.src.tar.xz': '54fc534f0da09088adbaa6c3bfc9899a500153b96e60c2fb9322a7aa37b1027a'},
+    {'third-party-17.0.3.src.tar.xz': '6e84ff16044d698ff0f24e7445f9f47818e6523913a006a5e1ea79625b429b7b'},
+]
+
+builddependencies = [
+    ('binutils', '2.39'),
+    ('CMake', '3.24.3'),
+    ('Python', '3.10.8'),
+]
+
+dependencies = [
+    ('ncurses', '6.3'),
+    ('zlib', '1.2.12'),
+]
+
+build_shared_libs = True
+
+sanity_check_paths = {
+    'files': ['bin/llvm-ar', 'bin/FileCheck'],
+    'dirs': ['include/llvm', 'include/llvm-c'],
+}
+
+sanity_check_commands = ["llvm-ar --help"]
+
+moduleclass = 'compiler'