diff --git a/artiq/compiler/targets.py b/artiq/compiler/targets.py
index 5f043eb0e3..5e4d0d78da 100644
--- a/artiq/compiler/targets.py
+++ b/artiq/compiler/targets.py
@@ -2,7 +2,6 @@
 from artiq.compiler import types, ir
 from llvmlite import ir as ll, binding as llvm
 
-llvm.initialize()
 llvm.initialize_all_targets()
 llvm.initialize_all_asmprinters()
 
@@ -108,35 +107,19 @@ def target_machine(self):
         return llmachine
 
     def optimize(self, llmodule):
-        llpassmgr = llvm.create_module_pass_manager()
-
-        # Register our alias analysis passes.
-        llpassmgr.add_basic_alias_analysis_pass()
-        llpassmgr.add_type_based_alias_analysis_pass()
-
-        # Start by cleaning up after our codegen and exposing as much
-        # information to LLVM as possible.
-        llpassmgr.add_constant_merge_pass()
-        llpassmgr.add_cfg_simplification_pass()
-        llpassmgr.add_instruction_combining_pass()
-        llpassmgr.add_sroa_pass()
-        llpassmgr.add_dead_code_elimination_pass()
-        llpassmgr.add_function_attrs_pass()
-        llpassmgr.add_global_optimizer_pass()
-
-        # Now, actually optimize the code.
-        llpassmgr.add_function_inlining_pass(275)
-        llpassmgr.add_ipsccp_pass()
-        llpassmgr.add_instruction_combining_pass()
-        llpassmgr.add_gvn_pass()
-        llpassmgr.add_cfg_simplification_pass()
-        llpassmgr.add_licm_pass()
-
-        # Clean up after optimizing.
-        llpassmgr.add_dead_arg_elimination_pass()
-        llpassmgr.add_global_dce_pass()
-
-        llpassmgr.run(llmodule)
+        llmachine = self.target_machine()
+        pto = llvm.create_pipeline_tuning_options(size_level=1)
+
+        # This combination of levels gets mapped to the -Os PassManagerBuilder default in
+        # llvmlite 0.45. The mapping is slightly nonsensical in that -Oz (which is more
+        # aggressively optimizing for size at the expense of runtime) is accessed via
+        # speed_level=size_level=2.
+        pto.speed_level = 1
+
+        pb = llvm.create_pass_builder(llmachine, pto)
+        llpassmgr = pb.getModulePassManager()
+
+        llpassmgr.run(llmodule, pb)
 
     def compile(self, module):
         """Compile the module to a relocatable object for this target."""
diff --git a/artiq/firmware/ksupport/ksupport.ld b/artiq/firmware/ksupport/ksupport.ld
index 24c4d2524f..4f3dd6265a 100644
--- a/artiq/firmware/ksupport/ksupport.ld
+++ b/artiq/firmware/ksupport/ksupport.ld
@@ -71,5 +71,6 @@ SECTIONS
     /DISCARD/ :
     {
         *(.debug*)
+        *(.riscv.attributes)
     }
 }
diff --git a/artiq/test/lit/embedding/annotation.py b/artiq/test/lit/embedding/annotation.py
index 21ae253322..7d79fbfc07 100644
--- a/artiq/test/lit/embedding/annotation.py
+++ b/artiq/test/lit/embedding/annotation.py
@@ -4,7 +4,7 @@
 from artiq.language.core import *
 from artiq.language.types import *
 
-# CHECK: i64 @_Z13testbench.foozz\(i64 %ARG.x, \{ i1, i64 \} %ARG.y\)
+# CHECK-L: i64 @_Z13testbench.foozz(i64
 
 @kernel
 def foo(x: TInt64, y: TInt64 = 1) -> TInt64:
diff --git a/artiq/test/lit/embedding/annotation_py.py b/artiq/test/lit/embedding/annotation_py.py
index c790b69145..86da7f031e 100644
--- a/artiq/test/lit/embedding/annotation_py.py
+++ b/artiq/test/lit/embedding/annotation_py.py
@@ -8,19 +8,19 @@
 from artiq.language.core import *
 from artiq.language.types import *
 
-# CHECK-L: i64 @_Z13testbench.foozz(i64 %ARG.x, { i1, i32 } %ARG.y)
+# CHECK-L: i64 @_Z13testbench.foozz(i64
 
 @kernel
 def foo(x: np.int64, y: np.int32 = 1) -> np.int64:
     print(x + y)
     return x + y
 
-# CHECK-L: void @_Z13testbench.barzz()
+# CHECK-L: void @_Z13testbench.barzz(i32
 @kernel
 def bar(x: np.int32) -> None:
     print(x)
 
-# CHECK-L: @_Z21testbench.unpack_listzz({ i1, i64 }* nocapture writeonly sret({ i1, i64 }) %.1, { i64*, i32 }* %ARG.xs)
+# CHECK-L: @_Z21testbench.unpack_listzz(ptr
 @kernel
 def unpack_list(xs: List[np.int64]) -> Tuple[bool, np.int64]:
     print(xs)
diff --git a/artiq/test/lit/embedding/index_tuple.py b/artiq/test/lit/embedding/index_tuple.py
index fced902016..90f8f47e3d 100644
--- a/artiq/test/lit/embedding/index_tuple.py
+++ b/artiq/test/lit/embedding/index_tuple.py
@@ -4,7 +4,7 @@
 from artiq.language.core import *
 from artiq.language.types import *
 
-# CHECK-L: void @_Z16testbench.unpackzz({ i32, { i8*, i32 }, i1 } %ARG.x)
+# CHECK-L: void @_Z16testbench.unpackzz({ i32, { ptr, i32 }, i1 } %ARG.x)
 
 @kernel
 def unpack(x):
diff --git a/artiq/test/lit/embedding/invariant_propagation.py b/artiq/test/lit/embedding/invariant_propagation.py
index e1af5c9c1c..71a7f852b7 100644
--- a/artiq/test/lit/embedding/invariant_propagation.py
+++ b/artiq/test/lit/embedding/invariant_propagation.py
@@ -15,8 +15,8 @@ def run(self):
         if self.foo:
             print("bar")
         else:
-            # Make sure all the code for this branch will be completely elided:
-            # CHECK-NOT: baz
+            # The kernel_invariant annotation should generate !invariant.load metadata
+            # CHECK: invariant.load
             print("baz")
 
 obj = Class()
diff --git a/artiq/test/lit/embedding/subkernel_message_recv.py b/artiq/test/lit/embedding/subkernel_message_recv.py
index 35e094aa64..dcc4e70503 100644
--- a/artiq/test/lit/embedding/subkernel_message_recv.py
+++ b/artiq/test/lit/embedding/subkernel_message_recv.py
@@ -9,13 +9,13 @@ def entrypoint():
     # CHECK: call void @subkernel_load_run\(i32 1, i8 1, i1 true\), !dbg !.
     message_pass()
     # CHECK-NOT: call void @subkernel_send_message\(i32 ., i1 false, i8 1, i8 1, .*\), !dbg !.
-    # CHECK: call i8 @subkernel_await_message\(i32 2, i64 -1, { i8\*, i32 }\* nonnull .*, i8 1, i8 1\), !dbg !.
+    # CHECK: call i8 @subkernel_await_message\(i32 2, i64 -1, ptr nonnull .*, i8 1, i8 1\), !dbg !.
     subkernel_recv("message", TInt32)
 
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
 # CHECK-NOT-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
-# CHECK-L: declare i8 @subkernel_await_message(i32, i64, { i8*, i32 }*, i8, i8) local_unnamed_addr
+# CHECK-L: declare i8 @subkernel_await_message(i32, i64, ptr, i8, i8) local_unnamed_addr
 # CHECK-NOT-L: declare void @subkernel_await_finish(i32, i64) local_unnamed_addr
 @subkernel(destination=1)
 def message_pass() -> TNone:
diff --git a/artiq/test/lit/embedding/subkernel_message_send.py b/artiq/test/lit/embedding/subkernel_message_send.py
index 3f0f77e357..04b9da0359 100644
--- a/artiq/test/lit/embedding/subkernel_message_send.py
+++ b/artiq/test/lit/embedding/subkernel_message_send.py
@@ -14,7 +14,7 @@ def entrypoint():
 
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
-# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
+# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, ptr, ptr) local_unnamed_addr
 @subkernel(destination=1)
 def message_pass() -> TNone:
     subkernel_recv("message", TInt32)
diff --git a/artiq/test/lit/embedding/subkernel_return.py b/artiq/test/lit/embedding/subkernel_return.py
index 3c9d1169af..fe1777253a 100644
--- a/artiq/test/lit/embedding/subkernel_return.py
+++ b/artiq/test/lit/embedding/subkernel_return.py
@@ -9,13 +9,13 @@ def entrypoint():
     # CHECK: call void @subkernel_load_run\(i32 1, i8 1, i1 true\), !dbg !.
     # CHECK-NOT: call void @subkernel_send_message\(.*\), !dbg !.
     returning()
-    # CHECK: call i8 @subkernel_await_message\(i32 1, i64 -1, { i8\*, i32 }\* nonnull .*, i8 1, i8 1\), !dbg !.
+    # CHECK: call i8 @subkernel_await_message\(i32 1, i64 -1, ptr nonnull .*, i8 1, i8 1\), !dbg !.
     # CHECK: call void @subkernel_await_finish\(i32 1, i64 -1\), !dbg !.
     subkernel_await(returning)
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
 # CHECK-NOT-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
-# CHECK-L: declare i8 @subkernel_await_message(i32, i64, { i8*, i32 }*, i8, i8) local_unnamed_addr
+# CHECK-L: declare i8 @subkernel_await_message(i32, i64, ptr, i8, i8) local_unnamed_addr
 # CHECK-L: declare void @subkernel_await_finish(i32, i64) local_unnamed_addr
 @subkernel(destination=1)
 def returning() -> TInt32:
diff --git a/artiq/test/lit/embedding/subkernel_self_args.py b/artiq/test/lit/embedding/subkernel_self_args.py
index 5aebed2e91..44aae9ab19 100644
--- a/artiq/test/lit/embedding/subkernel_self_args.py
+++ b/artiq/test/lit/embedding/subkernel_self_args.py
@@ -22,4 +22,4 @@ def entrypoint():
     a.kernel_entrypoint()
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
-# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
+# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, ptr, ptr) local_unnamed_addr
diff --git a/artiq/test/lit/embedding/subkernel_with_arg.py b/artiq/test/lit/embedding/subkernel_with_arg.py
index 1145165864..86e61140f8 100644
--- a/artiq/test/lit/embedding/subkernel_with_arg.py
+++ b/artiq/test/lit/embedding/subkernel_with_arg.py
@@ -12,7 +12,7 @@ def entrypoint():
 
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
-# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
+# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, ptr, ptr) local_unnamed_addr
 @subkernel(destination=1)
 def accept_arg(arg: TInt32) -> TNone:
     pass
diff --git a/artiq/test/lit/embedding/subkernel_with_opt_arg.py b/artiq/test/lit/embedding/subkernel_with_opt_arg.py
index fb5cc3df12..91b2c1aeeb 100644
--- a/artiq/test/lit/embedding/subkernel_with_opt_arg.py
+++ b/artiq/test/lit/embedding/subkernel_with_opt_arg.py
@@ -15,7 +15,7 @@ def entrypoint():
 
 
 # CHECK-L: declare void @subkernel_load_run(i32, i8, i1) local_unnamed_addr
-# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, { i8*, i32 }*, i8**) local_unnamed_addr
+# CHECK-L: declare void @subkernel_send_message(i32, i1, i8, i8, ptr, ptr) local_unnamed_addr
 @subkernel(destination=1)
 def accept_arg(arg_a, arg_b=5) -> TNone:
     pass
diff --git a/artiq/test/lit/embedding/syscall_arg_attrs.py b/artiq/test/lit/embedding/syscall_arg_attrs.py
index 8d0c05c34d..616201451d 100644
--- a/artiq/test/lit/embedding/syscall_arg_attrs.py
+++ b/artiq/test/lit/embedding/syscall_arg_attrs.py
@@ -11,20 +11,20 @@
 
 @kernel
 def entrypoint():
-    # CHECK: call void @accept_str\({ i8\*, i32 }
+    # CHECK: call void @accept_str\({ ptr, i32 }
     accept_str("foo")
 
-    # CHECK: call void @return_str\({ i8\*, i32 }\* nonnull sret
+    # CHECK: call void @return_str\(ptr nonnull sret
     return_str()
 
 
-# CHECK: declare void @accept_str\({ i8\*, i32 }\)
+# CHECK: declare void @accept_str\({ ptr, i32 }\)
 @syscall
 def accept_str(name: TStr) -> TNone:
     pass
 
 
-# CHECK: declare void @return_str\({ i8\*, i32 }\* sret\({ i8\*, i32 }\)\)
+# CHECK: declare void @return_str\(ptr sret\({ ptr, i32 }\)\)
 @syscall
 def return_str() -> TStr:
     pass
diff --git a/artiq/test/lit/embedding/syscall_flags.py b/artiq/test/lit/embedding/syscall_flags.py
index b2e27d6a07..a7c3c3caec 100644
--- a/artiq/test/lit/embedding/syscall_flags.py
+++ b/artiq/test/lit/embedding/syscall_flags.py
@@ -6,7 +6,7 @@
 
 # CHECK: call void @foo\(\)(, !dbg !\d+)?
 
-# CHECK-L: ; Function Attrs: inaccessiblememonly nounwind
+# CHECK-L: ; Function Attrs: nounwind memory(inaccessiblemem: readwrite)
 # CHECK-NEXT-L: declare void @foo()
 
 @syscall(flags={"nounwind", "nowrite"})
@@ -15,7 +15,7 @@ def foo() -> TNone:
 
 # sret nowrite functions shouldn't be marked inaccessiblememonly.
 # CHECK-L: ; Function Attrs: nounwind
-# CHECK-NEXT-L: declare void @bar({ i32, i64 }* sret({ i32, i64 }))
+# CHECK-NEXT-L: declare void @bar(ptr sret({ i32, i64 }))
 @syscall(flags={"nounwind", "nowrite"})
 def bar() -> TTuple([TInt32, TInt64]):
     pass
diff --git a/flake.nix b/flake.nix
index 89aae88d62..f888e96518 100644
--- a/flake.nix
+++ b/flake.nix
@@ -74,8 +74,6 @@
       QML2_IMPORT_PATH = "${qtbase}/${qtQmlPrefix}";
     };
 
-    inherit (pkgs.callPackage ./llvm {}) llvm_15 lld_15 llvmPackages_15;
-
     rust = pkgs.rust-bin.nightly."2021-09-01".default.override {
       extensions = ["rust-src"];
       targets = [];
@@ -158,30 +156,6 @@
       '';
     };
 
-    llvmlite-new = pkgs.python3Packages.buildPythonPackage rec {
-      pname = "llvmlite";
-      version = "0.44.0";
-      src = pkgs.fetchFromGitHub {
-        owner = "numba";
-        repo = "llvmlite";
-        rev = "v${version}";
-        sha256 = "sha256-ZIA/JfK9ZP00Zn6SZuPus30Xw10hn3DArHCkzBZAUV0=";
-      };
-      pyproject = true;
-      build-system = [pkgs.python3Packages.setuptools];
-      nativeBuildInputs = [llvm_15];
-      # Disable static linking
-      # https://github.com/numba/llvmlite/issues/93
-      postPatch = ''
-        substituteInPlace ffi/Makefile.linux --replace "-static-libstdc++" ""
-        substituteInPlace llvmlite/tests/test_binding.py --replace "test_linux" "nope"
-      '';
-      # Set directory containing llvm-config binary
-      preConfigure = ''
-        export LLVM_CONFIG=${llvm_15.dev}/bin/llvm-config
-      '';
-    };
-
     artiq-upstream = pkgs.python3Packages.buildPythonPackage rec {
       pname = "artiq";
       version = artiqVersion;
@@ -195,10 +169,9 @@
       '';
 
       nativeBuildInputs = [pkgs.qt6.wrapQtAppsHook];
-      # keep llvm_x and lld_x in sync with llvmlite
       propagatedBuildInputs =
-        [llvm_15 lld_15 sipyco.packages.x86_64-linux.sipyco pythonparser llvmlite-new pkgs.qt6.qtsvg artiq-comtools.packages.x86_64-linux.artiq-comtools]
-        ++ (with pkgs.python3Packages; [pyqtgraph pygit2 numpy dateutil scipy prettytable pyserial levenshtein h5py pyqt6 qasync tqdm lmdb jsonschema platformdirs]);
+        [pkgs.llvm_20 pkgs.lld_20 sipyco.packages.x86_64-linux.sipyco pythonparser pkgs.qt6.qtsvg artiq-comtools.packages.x86_64-linux.artiq-comtools]
+        ++ (with pkgs.python3Packages; [llvmlite pyqtgraph pygit2 numpy dateutil scipy prettytable pyserial levenshtein h5py pyqt6 qasync tqdm lmdb jsonschema platformdirs]);
 
       dontWrapQtApps = true;
       postFixup = ''
@@ -219,10 +192,10 @@
         "--set FONTCONFIG_FILE ${pkgs.fontconfig.out}/etc/fonts/fonts.conf"
       ];
 
-      # FIXME: automatically propagate lld_15 llvm_15 dependencies
+      # FIXME: automatically propagate lld_20 llvm_20 dependencies
       # cacert is required in the check stage only, as certificates are to be
       # obtained from system elsewhere
-      nativeCheckInputs = [lld_15 llvm_15 libartiq-support pkgs.lit pkgs.outputcheck pkgs.cacert];
+      nativeCheckInputs = with pkgs; [lld_20 llvm_20 lit outputcheck cacert] ++ [libartiq-support];
       checkPhase = ''
         python -m unittest discover -v artiq.test
 
@@ -308,9 +281,9 @@
         nativeBuildInputs = [
           (pkgs.python3.withPackages (ps: [migen misoc (artiq.withExperimentalFeatures experimentalFeatures) ps.packaging]))
           rust
-          llvm_15
-          lld_15
-          llvmPackages_15.clang-unwrapped
+          pkgs.llvm_20
+          pkgs.lld_20
+          pkgs.llvmPackages_20.clang-unwrapped
           vivado
         ];
         overrideMain = _: {
@@ -498,6 +471,9 @@
           [
             git
             lit
+            lld_20
+            llvm_20
+            llvmPackages_20.clang-unwrapped
             outputcheck
             pdf2svg
 
@@ -510,9 +486,6 @@
             (python3.withPackages (ps: [migen misoc microscope ps.packaging ps.paramiko] ++ artiq.propagatedBuildInputs))
           ]
           ++ [
-            llvm_15
-            lld_15
-            llvmPackages_15.clang-unwrapped
             rust
             latex-artiq-manual
             artiq-frontend-dev-wrappers
@@ -538,9 +511,9 @@
         packages = [
           rust
 
-          llvm_15
-          lld_15
-          llvmPackages_15.clang-unwrapped
+          pkgs.llvm_20
+          pkgs.lld_20
+          pkgs.llvmPackages_20.clang-unwrapped
 
           packages.x86_64-linux.vivado
           packages.x86_64-linux.openocd-bscanspi
@@ -584,8 +557,8 @@
                 ]
                 ++ ps.paramiko.optional-dependencies.ed25519
           ))
-          llvm_15
-          lld_15
+          pkgs.llvm_20
+          pkgs.lld_20
           pkgs.openssh
           packages.x86_64-linux.openocd-bscanspi # for the bscanspi bitstreams
         ];
diff --git a/llvm/15/clang/default.nix b/llvm/15/clang/default.nix
deleted file mode 100644
index d4e8d3558b..0000000000
--- a/llvm/15/clang/default.nix
+++ /dev/null
@@ -1,97 +0,0 @@
-{
-  lib,
-  stdenv,
-  cmake,
-  ninja,
-  python3,
-  libxml2,
-  runCommand,
-  libllvm,
-  src,
-  version,
-  llvm_meta,
-  getVersionFile,
-}:
-stdenv.mkDerivation {
-  pname = "clang";
-  inherit version;
-
-  # Extract clang from monorepo
-  src = runCommand "clang-src-${version}" {} ''
-    mkdir -p "$out"
-    cp -r ${src}/cmake "$out"
-    cp -r ${src}/clang "$out"
-    cp -r ${src}/clang-tools-extra "$out"
-  '';
-
-  sourceRoot = "clang-src-${version}/clang";
-
-  outputs = [
-    "out"
-    "lib"
-    "dev"
-    "python"
-  ];
-
-  patches = [
-    (getVersionFile "clang/purity.patch")
-    (getVersionFile "clang/gnu-install-dirs.patch")
-  ];
-
-  nativeBuildInputs = [
-    cmake
-    ninja
-    python3
-  ];
-  buildInputs = [
-    libxml2
-    libllvm
-  ];
-
-  cmakeFlags = [
-    "-DLLVM_ENABLE_RTTI=ON"
-    "-DCLANG_INSTALL_PACKAGE_DIR=${placeholder "dev"}/lib/cmake/clang"
-    "-DLLVM_TABLEGEN_EXE=${libllvm.dev}/bin/llvm-tblgen"
-  ];
-
-  postPatch = ''
-    # Link clang-tools-extra
-    (cd tools && ln -s ../../clang-tools-extra extra)
-  '';
-
-  postInstall = ''
-    # Create cpp symlink
-    ln -sv $out/bin/clang $out/bin/cpp
-
-    # Move libclang to lib output
-    moveToOutput "lib/libclang.*" "$lib"
-    moveToOutput "lib/libclang-cpp.*" "$lib"
-
-    # Setup python output
-    mkdir -p $python/bin $python/share/clang/
-    mv $out/bin/{git-clang-format,scan-view} $python/bin
-    if [ -e $out/bin/set-xcode-analyzer ]; then
-      mv $out/bin/set-xcode-analyzer $python/bin
-    fi
-    mv $out/share/clang/*.py $python/share/clang
-
-    # Remove test binary
-    rm $out/bin/c-index-test
-
-    # Move tblgen to dev
-    mkdir -p $dev/bin
-    cp bin/clang-tblgen $dev/bin
-  '';
-
-  passthru = {
-    inherit libllvm;
-    isClang = true;
-  };
-
-  meta =
-    llvm_meta
-    // {
-      description = "C language family frontend for LLVM";
-      homepage = "https://clang.llvm.org/";
-    };
-}
diff --git a/llvm/15/clang/gnu-install-dirs.patch b/llvm/15/clang/gnu-install-dirs.patch
deleted file mode 100644
index f767c56836..0000000000
--- a/llvm/15/clang/gnu-install-dirs.patch
+++ /dev/null
@@ -1,105 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index c27beec313d7..480f13e73c9f 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -78,15 +78,17 @@ if(CLANG_BUILT_STANDALONE)
-   if (NOT LLVM_CONFIG_FOUND)
-     # Pull values from LLVMConfig.cmake.  We can drop this once the llvm-config
-     # path is removed.
--    set(MAIN_INCLUDE_DIR "${LLVM_INCLUDE_DIR}")
-+    set(INCLUDE_DIRS ${LLVM_INCLUDE_DIRS})
-     set(LLVM_OBJ_DIR "${LLVM_BINARY_DIR}")
-     # N.B. this is just a default value, the CACHE PATHs below can be overriden.
-     set(MAIN_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../llvm")
-     set(TOOLS_BINARY_DIR "${LLVM_TOOLS_BINARY_DIR}")
-     set(LIBRARY_DIR "${LLVM_LIBRARY_DIR}")
-+  else()
-+    set(INCLUDE_DIRS "${LLVM_BINARY_DIR}/include" "${MAIN_INCLUDE_DIR}")
-   endif()
- 
--  set(LLVM_MAIN_INCLUDE_DIR "${MAIN_INCLUDE_DIR}" CACHE PATH "Path to llvm/include")
-+  set(LLVM_INCLUDE_DIRS ${INCLUDE_DIRS} CACHE PATH "Path to llvm/include and any other header dirs needed")
-   set(LLVM_BINARY_DIR "${LLVM_OBJ_ROOT}" CACHE PATH "Path to LLVM build tree")
-   set(LLVM_MAIN_SRC_DIR "${MAIN_SRC_DIR}" CACHE PATH "Path to LLVM source tree")
-   set(LLVM_TOOLS_BINARY_DIR "${TOOLS_BINARY_DIR}" CACHE PATH "Path to llvm/bin")
-@@ -128,7 +130,7 @@ if(CLANG_BUILT_STANDALONE)
-     set(LLVM_INCLUDE_TESTS ON)
-   endif()
- 
--  include_directories("${LLVM_BINARY_DIR}/include" "${LLVM_MAIN_INCLUDE_DIR}")
-+  include_directories(${LLVM_INCLUDE_DIRS})
-   link_directories("${LLVM_LIBRARY_DIR}")
- 
-   set( CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin )
-diff --git a/cmake/modules/AddClang.cmake b/cmake/modules/AddClang.cmake
-index 21ac332e4f5f..b16c314bd1e2 100644
---- a/cmake/modules/AddClang.cmake
-+++ b/cmake/modules/AddClang.cmake
-@@ -119,8 +119,8 @@ macro(add_clang_library name)
-         install(TARGETS ${lib}
-           COMPONENT ${lib}
-           ${export_to_clangtargets}
--          LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
--          ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-+          LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-+          ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-           RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
- 
-         if (NOT LLVM_ENABLE_IDE)
-diff --git a/lib/Headers/CMakeLists.txt b/lib/Headers/CMakeLists.txt
-index 6e2060991b92..b9bc930d26b8 100644
---- a/lib/Headers/CMakeLists.txt
-+++ b/lib/Headers/CMakeLists.txt
-@@ -420,7 +420,7 @@ add_header_target("openmp-resource-headers" ${openmp_wrapper_files})
- add_header_target("windows-resource-headers" ${windows_only_files})
- add_header_target("utility-resource-headers" ${utility_files})
- 
--set(header_install_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
-+set(header_install_dir ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
- 
- #############################################################
- # Install rules for the catch-all clang-resource-headers target
-diff --git a/tools/libclang/CMakeLists.txt b/tools/libclang/CMakeLists.txt
-index 8d95d0900e8c..ebc70ff7526d 100644
---- a/tools/libclang/CMakeLists.txt
-+++ b/tools/libclang/CMakeLists.txt
-@@ -180,7 +180,7 @@ foreach(PythonVersion ${CLANG_PYTHON_BINDINGS_VERSIONS})
-           COMPONENT
-             libclang-python-bindings
-           DESTINATION
--            "lib${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
-+            "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
- endforeach()
- if(NOT LLVM_ENABLE_IDE)
-   add_custom_target(libclang-python-bindings)
-diff --git a/tools/scan-build-py/CMakeLists.txt b/tools/scan-build-py/CMakeLists.txt
-index 061dc7ef4dd9..adc54b2edc32 100644
---- a/tools/scan-build-py/CMakeLists.txt
-+++ b/tools/scan-build-py/CMakeLists.txt
-@@ -88,7 +88,7 @@ foreach(lib ${LibScanbuild})
-                      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/lib/libscanbuild/${lib})
-   list(APPEND Depends ${CMAKE_BINARY_DIR}/lib/libscanbuild/${lib})
-   install(PROGRAMS lib/libscanbuild/${lib}
--          DESTINATION lib/libscanbuild
-+          DESTINATION "${CMAKE_INSTALL_LIBDIR}/libscanbuild"
-           COMPONENT scan-build-py)
- endforeach()
- 
-@@ -106,7 +106,7 @@ foreach(resource ${LibScanbuildResources})
-                      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/lib/libscanbuild/resources/${resource})
-   list(APPEND Depends ${CMAKE_BINARY_DIR}/lib/libscanbuild/resources/${resource})
-   install(PROGRAMS lib/libscanbuild/resources/${resource}
--          DESTINATION lib/libscanbuild/resources
-+          DESTINATION "${CMAKE_INSTALL_LIBDIR}/libscanbuild/resources"
-           COMPONENT scan-build-py)
- endforeach()
- 
-@@ -122,7 +122,7 @@ foreach(lib ${LibEar})
-                      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/lib/libear/${lib})
-   list(APPEND Depends ${CMAKE_BINARY_DIR}/lib/libear/${lib})
-   install(PROGRAMS lib/libear/${lib}
--          DESTINATION lib/libear
-+          DESTINATION "${CMAKE_INSTALL_LIBDIR}/libear"
-           COMPONENT scan-build-py)
- endforeach()
- 
diff --git a/llvm/15/clang/purity.patch b/llvm/15/clang/purity.patch
deleted file mode 100644
index 1c94f293eb..0000000000
--- a/llvm/15/clang/purity.patch
+++ /dev/null
@@ -1,29 +0,0 @@
-From 4add81bba40dcec62c4ea4481be8e35ac53e89d8 Mon Sep 17 00:00:00 2001
-From: Will Dietz <w@wdtz.org>
-Date: Thu, 18 May 2017 11:56:12 -0500
-Subject: [PATCH] "purity" patch for 5.0
-
----
- lib/Driver/ToolChains/Gnu.cpp | 7 -------
- 1 file changed, 7 deletions(-)
-
-diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
-index fe3c0191bb..c6a482bece 100644
---- a/lib/Driver/ToolChains/Gnu.cpp
-+++ b/lib/Driver/ToolChains/Gnu.cpp
-@@ -487,13 +487,7 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
-   } else {
-     if (Args.hasArg(options::OPT_rdynamic))
-       CmdArgs.push_back("-export-dynamic");
-
--    if (!Args.hasArg(options::OPT_shared) && !IsStaticPIE &&
--        !Args.hasArg(options::OPT_r)) {
--      CmdArgs.push_back("-dynamic-linker");
--      CmdArgs.push_back(Args.MakeArgString(Twine(D.DyldPrefix) +
--                                           ToolChain.getDynamicLinker(Args)));
--    }
-   }
- 
-   CmdArgs.push_back("-o");
--- 
-2.11.0
diff --git a/llvm/15/lld/default.nix b/llvm/15/lld/default.nix
deleted file mode 100644
index 653c33727b..0000000000
--- a/llvm/15/lld/default.nix
+++ /dev/null
@@ -1,49 +0,0 @@
-{
-  lib,
-  stdenv,
-  cmake,
-  ninja,
-  libxml2,
-  libllvm,
-  runCommand,
-  src,
-  version,
-  llvm_meta,
-  getVersionFile,
-}:
-stdenv.mkDerivation {
-  pname = "lld";
-  inherit version;
-
-  src = runCommand "lld-src-${version}" {} ''
-    mkdir -p "$out"
-    cp -r ${src}/cmake "$out"
-    cp -r ${src}/lld "$out"
-    mkdir -p "$out/libunwind"
-    cp -r ${src}/libunwind/include "$out/libunwind"
-    mkdir -p "$out/llvm"
-  '';
-
-  sourceRoot = "lld-src-${version}/lld";
-
-  outputs = ["out" "lib" "dev"];
-
-  patches = [
-    (getVersionFile "lld/gnu-install-dirs.patch")
-  ];
-
-  nativeBuildInputs = [cmake ninja];
-  buildInputs = [libllvm libxml2];
-
-  cmakeFlags = [
-    "-DLLD_INSTALL_PACKAGE_DIR=${placeholder "dev"}/lib/cmake/lld"
-    "-DLLVM_TABLEGEN_EXE=${libllvm.dev}/bin/llvm-tblgen"
-  ];
-
-  meta =
-    llvm_meta
-    // {
-      description = "LLVM linker";
-      homepage = "https://lld.llvm.org/";
-    };
-}
diff --git a/llvm/15/lld/gnu-install-dirs.patch b/llvm/15/lld/gnu-install-dirs.patch
deleted file mode 100644
index ea62b2ad50..0000000000
--- a/llvm/15/lld/gnu-install-dirs.patch
+++ /dev/null
@@ -1,46 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index dcc649629a4b..58dca54642e4 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -70,13 +70,15 @@ if(LLD_BUILT_STANDALONE)
-   if (NOT LLVM_CONFIG_FOUND)
-     # Pull values from LLVMConfig.cmake.  We can drop this once the llvm-config
-     # path is removed.
--    set(MAIN_INCLUDE_DIR "${LLVM_INCLUDE_DIR}")
-+    set(INCLUDE_DIRS ${LLVM_INCLUDE_DIRS})
-     set(LLVM_OBJ_DIR "${LLVM_BINARY_DIR}")
-     # N.B. this is just a default value, the CACHE PATHs below can be overridden.
-     set(MAIN_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../llvm")
-+  else()
-+    set(INCLUDE_DIRS "${LLVM_BINARY_DIR}/include" "${MAIN_INCLUDE_DIR}")
-   endif()
- 
--  set(LLVM_MAIN_INCLUDE_DIR "${MAIN_INCLUDE_DIR}" CACHE PATH "Path to llvm/include")
-+  set(LLVM_INCLUDE_DIRS ${INCLUDE_DIRS} CACHE PATH "Path to llvm/include and any other header dirs needed")
-   set(LLVM_BINARY_DIR "${LLVM_OBJ_ROOT}" CACHE PATH "Path to LLVM build tree")
-   set(LLVM_MAIN_SRC_DIR "${MAIN_SRC_DIR}" CACHE PATH "Path to LLVM source tree")
- 
-@@ -95,7 +97,7 @@ if(LLD_BUILT_STANDALONE)
- 
-   set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
- 
--  include_directories("${LLVM_BINARY_DIR}/include" ${LLVM_INCLUDE_DIRS})
-+  include_directories(${LLVM_INCLUDE_DIRS})
-   link_directories(${LLVM_LIBRARY_DIRS})
- 
-   if(LLVM_INCLUDE_TESTS)
-diff --git a/cmake/modules/AddLLD.cmake b/cmake/modules/AddLLD.cmake
-index d3924f7243d4..42a7cd62281c 100644
---- a/cmake/modules/AddLLD.cmake
-+++ b/cmake/modules/AddLLD.cmake
-@@ -18,8 +18,8 @@ macro(add_lld_library name)
-     install(TARGETS ${name}
-       COMPONENT ${name}
-       ${export_to_lldtargets}
--      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
--      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-       RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
- 
-     if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
diff --git a/llvm/15/llvm/default.nix b/llvm/15/llvm/default.nix
deleted file mode 100644
index 8cbf6c75f9..0000000000
--- a/llvm/15/llvm/default.nix
+++ /dev/null
@@ -1,86 +0,0 @@
-{
-  lib,
-  stdenv,
-  cmake,
-  ninja,
-  python3,
-  libffi,
-  libxml2,
-  ncurses,
-  zlib,
-  runCommand,
-  src,
-  version,
-  llvm_meta,
-  getVersionFile,
-}:
-stdenv.mkDerivation {
-  pname = "llvm";
-  inherit version;
-
-  src = runCommand "llvm-src-${version}" {} ''
-    mkdir -p "$out"
-    cp -r ${src}/llvm "$out"
-    cp -r ${src}/cmake "$out"
-    cp -r ${src}/third-party "$out"
-  '';
-
-  sourceRoot = "llvm-src-${version}/llvm";
-
-  outputs = ["out" "lib" "dev" "python"];
-
-  patches = [
-    (getVersionFile "llvm/gnu-install-dirs.patch")
-    (getVersionFile "llvm/llvm-lit-cfg-add-libs-to-dylib-path.patch")
-    (getVersionFile "llvm/lit-shell-script-runner-set-dyld-library-path.patch")
-  ];
-
-  nativeBuildInputs = [cmake ninja python3];
-  buildInputs = [libxml2 libffi];
-  propagatedBuildInputs = [ncurses zlib];
-
-  cmakeBuildType = "Release";
-
-  cmakeFlags = [
-    "-DLLVM_INSTALL_PACKAGE_DIR=${placeholder "dev"}/lib/cmake/llvm"
-    "-DLLVM_ENABLE_RTTI=ON"
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
-    "-DLLVM_INSTALL_UTILS=ON"
-    "-DLLVM_BUILD_TESTS=OFF"
-    "-DLLVM_ENABLE_FFI=ON"
-    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_ENABLE_DUMP=ON"
-    "-DLLVM_ENABLE_TERMINFO=ON"
-    "-DLLVM_INCLUDE_TESTS=OFF"
-  ];
-
-  LDFLAGS = "-Wl,--build-id=sha1";
-
-  postInstall = ''
-    # Move opt-viewer to python output
-    mkdir -p $python/share
-    mv $out/share/opt-viewer $python/share/opt-viewer
-
-    # Move llvm-config to dev output
-    moveToOutput "bin/llvm-config*" "$dev"
-
-    # Move llvm-tblgen to dev output (needed by clang and lld)
-    moveToOutput "bin/llvm-tblgen" "$dev"
-
-    # Fix cmake config to point to dev output
-    substituteInPlace "$dev/lib/cmake/llvm/LLVMExports-release.cmake" \
-      --replace-fail "$out/bin/llvm-config" "$dev/bin/llvm-config" \
-      --replace-fail "$out/bin/llvm-tblgen" "$dev/bin/llvm-tblgen"
-
-    substituteInPlace "$dev/lib/cmake/llvm/LLVMConfig.cmake" \
-      --replace-fail 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}")' 'set(LLVM_BINARY_DIR "'"$lib"'")'
-  '';
-
-  meta =
-    llvm_meta
-    // {
-      description = "LLVM compiler infrastructure";
-      homepage = "https://llvm.org/";
-    };
-}
diff --git a/llvm/15/llvm/gnu-install-dirs.patch b/llvm/15/llvm/gnu-install-dirs.patch
deleted file mode 100644
index 0ef317af8c..0000000000
--- a/llvm/15/llvm/gnu-install-dirs.patch
+++ /dev/null
@@ -1,138 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 45399dc0537e..5d946e9e6583 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -942,7 +942,7 @@ if (NOT TENSORFLOW_AOT_PATH STREQUAL "")
-   add_subdirectory(${TENSORFLOW_AOT_PATH}/xla_aot_runtime_src
-     ${CMAKE_ARCHIVE_OUTPUT_DIRECTORY}/tf_runtime)
-   install(TARGETS tf_xla_runtime EXPORT LLVMExports
--    ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT tf_xla_runtime)
-+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX} COMPONENT tf_xla_runtime)
-   set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS tf_xla_runtime)
-   # Once we add more modules, we should handle this more automatically.
-   if (DEFINED LLVM_OVERRIDE_MODEL_HEADER_INLINERSIZEMODEL)
-diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
-index 057431208322..56f0dcb258da 100644
---- a/cmake/modules/AddLLVM.cmake
-+++ b/cmake/modules/AddLLVM.cmake
-@@ -844,8 +844,8 @@ macro(add_llvm_library name)
-       get_target_export_arg(${name} LLVM export_to_llvmexports ${umbrella})
-       install(TARGETS ${name}
-               ${export_to_llvmexports}
--              LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
--              ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
-+              LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" COMPONENT ${name}
-+              ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" COMPONENT ${name}
-               RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT ${name})
- 
-       if (NOT LLVM_ENABLE_IDE)
-@@ -2007,7 +2007,7 @@ function(llvm_install_library_symlink name dest type)
-   set(full_name ${CMAKE_${type}_LIBRARY_PREFIX}${name}${CMAKE_${type}_LIBRARY_SUFFIX})
-   set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
- 
--  set(output_dir lib${LLVM_LIBDIR_SUFFIX})
-+  set(output_dir ${CMAKE_INSTALL_FULL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
-   if(WIN32 AND "${type}" STREQUAL "SHARED")
-     set(output_dir "${CMAKE_INSTALL_BINDIR}")
-   endif()
-@@ -2271,15 +2271,15 @@ function(llvm_setup_rpath name)
- 
-   if (APPLE)
-     set(_install_name_dir INSTALL_NAME_DIR "@rpath")
--    set(_install_rpath "@loader_path/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-+    set(_install_rpath "@loader_path/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-   elseif(${CMAKE_SYSTEM_NAME} MATCHES "AIX" AND BUILD_SHARED_LIBS)
-     # $ORIGIN is not interpreted at link time by aix ld.
-     # Since BUILD_SHARED_LIBS is only recommended for use by developers,
-     # hardcode the rpath to build/install lib dir first in this mode.
-     # FIXME: update this when there is better solution.
--    set(_install_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" "${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-+    set(_install_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" "${CMAKE_INSTALL_FULL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-   elseif(UNIX)
--    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-+    set(_install_rpath "\$ORIGIN/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-     if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
-       set_property(TARGET ${name} APPEND_STRING PROPERTY
-                    LINK_FLAGS " -Wl,-z,origin ")
-diff --git a/cmake/modules/AddOCaml.cmake b/cmake/modules/AddOCaml.cmake
-index 891c9e6d618c..8d963f3b0069 100644
---- a/cmake/modules/AddOCaml.cmake
-+++ b/cmake/modules/AddOCaml.cmake
-@@ -147,9 +147,9 @@ function(add_ocaml_library name)
-   endforeach()
- 
-   if( APPLE )
--    set(ocaml_rpath "@executable_path/../../../lib${LLVM_LIBDIR_SUFFIX}")
-+    set(ocaml_rpath "@executable_path/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
-   elseif( UNIX )
--    set(ocaml_rpath "\\$ORIGIN/../../../lib${LLVM_LIBDIR_SUFFIX}")
-+    set(ocaml_rpath "\\$ORIGIN/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
-   endif()
-   list(APPEND ocaml_flags "-ldopt" "-Wl,-rpath,${ocaml_rpath}")
- 
-diff --git a/cmake/modules/CMakeLists.txt b/cmake/modules/CMakeLists.txt
-index d4b0ab959148..26ed981fd09f 100644
---- a/cmake/modules/CMakeLists.txt
-+++ b/cmake/modules/CMakeLists.txt
-@@ -128,7 +128,7 @@ set(LLVM_CONFIG_INCLUDE_DIRS
-   )
- list(REMOVE_DUPLICATES LLVM_CONFIG_INCLUDE_DIRS)
- 
--extend_path(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}" "lib\${LLVM_LIBDIR_SUFFIX}")
-+extend_path(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}" "${CMAKE_INSTALL_LIBDIR}\${LLVM_LIBDIR_SUFFIX}")
- set(LLVM_CONFIG_LIBRARY_DIRS
-   "${LLVM_CONFIG_LIBRARY_DIR}"
-   # FIXME: Should there be other entries here?
-diff --git a/docs/CMake.rst b/docs/CMake.rst
-index 879b7b231d4c..9c31d14e8950 100644
---- a/docs/CMake.rst
-+++ b/docs/CMake.rst
-@@ -250,7 +250,7 @@ description is in `LLVM-related variables`_ below.
- **LLVM_LIBDIR_SUFFIX**:STRING
-   Extra suffix to append to the directory where libraries are to be
-   installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
--  to install libraries to ``/usr/lib64``.
-+  to install libraries to ``/usr/lib64``. See also ``CMAKE_INSTALL_LIBDIR``.
- 
- **LLVM_PARALLEL_{COMPILE,LINK}_JOBS**:STRING
-   Building the llvm toolchain can use a lot of resources, particularly
-@@ -284,6 +284,10 @@ manual, or execute ``cmake --help-variable VARIABLE_NAME``.
-   The path to install executables, relative to the *CMAKE_INSTALL_PREFIX*.
-   Defaults to "bin".
- 
-+**CMAKE_INSTALL_LIBDIR**:PATH
-+  The path to install libraries, relative to the *CMAKE_INSTALL_PREFIX*.
-+  Defaults to "lib".
-+
- **CMAKE_INSTALL_INCLUDEDIR**:PATH
-   The path to install header files, relative to the *CMAKE_INSTALL_PREFIX*.
-   Defaults to "include".
-diff --git a/tools/llvm-config/BuildVariables.inc.in b/tools/llvm-config/BuildVariables.inc.in
-index 370005cd8d7d..7e790bc52111 100644
---- a/tools/llvm-config/BuildVariables.inc.in
-+++ b/tools/llvm-config/BuildVariables.inc.in
-@@ -23,6 +23,7 @@
- #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
- #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
- #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
-+#define LLVM_INSTALL_LIBDIR "@CMAKE_INSTALL_LIBDIR@"
- #define LLVM_INSTALL_INCLUDEDIR "@CMAKE_INSTALL_INCLUDEDIR@"
- #define LLVM_INSTALL_PACKAGE_DIR "@LLVM_INSTALL_PACKAGE_DIR@"
- #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
-diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
-index 2c6c55f89d38..f6d2068a0827 100644
---- a/tools/llvm-config/llvm-config.cpp
-+++ b/tools/llvm-config/llvm-config.cpp
-@@ -369,7 +369,11 @@ int main(int argc, char **argv) {
-       sys::fs::make_absolute(ActivePrefix, Path);
-       ActiveBinDir = std::string(Path.str());
-     }
--    ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
-+    {
-+      SmallString<256> Path(LLVM_INSTALL_LIBDIR LLVM_LIBDIR_SUFFIX);
-+      sys::fs::make_absolute(ActivePrefix, Path);
-+      ActiveLibDir = std::string(Path.str());
-+    }
-     {
-       SmallString<256> Path(LLVM_INSTALL_PACKAGE_DIR);
-       sys::fs::make_absolute(ActivePrefix, Path);
diff --git a/llvm/15/llvm/lit-shell-script-runner-set-dyld-library-path.patch b/llvm/15/llvm/lit-shell-script-runner-set-dyld-library-path.patch
deleted file mode 100644
index 32f1d13a9d..0000000000
--- a/llvm/15/llvm/lit-shell-script-runner-set-dyld-library-path.patch
+++ /dev/null
@@ -1,26 +0,0 @@
-diff --git a/utils/lit/lit/TestRunner.py b/utils/lit/lit/TestRunner.py
-index 0242e0b75af3..d732011306f7 100644
---- a/utils/lit/lit/TestRunner.py
-+++ b/utils/lit/lit/TestRunner.py
-@@ -1029,6 +1029,12 @@ def executeScript(test, litConfig, tmpBase, commands, cwd):
-             f.write('@echo off\n')
-         f.write('\n@if %ERRORLEVEL% NEQ 0 EXIT\n'.join(commands))
-     else:
-+        # This env var is *purged* when invoking subprocesses so we have to
-+        # manually set it from within the bash script in order for the commands
-+        # in run lines to see this var:
-+        if "DYLD_LIBRARY_PATH" in test.config.environment:
-+            f.write(f'export DYLD_LIBRARY_PATH="{test.config.environment["DYLD_LIBRARY_PATH"]}"\n')
-+
-         for i, ln in enumerate(commands):
-             match = re.match(kPdbgRegex, ln)
-             if match:
-@@ -1363,7 +1369,7 @@ def applySubstitutions(script, substitutions, conditions={},
-         return processed
- 
-     process = processLine if recursion_limit is None else processLineToFixedPoint
--    
-+
-     return [unescapePercents(process(ln)) for ln in script]
- 
- 
diff --git a/llvm/15/llvm/llvm-lit-cfg-add-libs-to-dylib-path.patch b/llvm/15/llvm/llvm-lit-cfg-add-libs-to-dylib-path.patch
deleted file mode 100644
index d824516c0a..0000000000
--- a/llvm/15/llvm/llvm-lit-cfg-add-libs-to-dylib-path.patch
+++ /dev/null
@@ -1,79 +0,0 @@
-diff --git a/test/Unit/lit.cfg.py b/test/Unit/lit.cfg.py
-index 81e8dc04acea..479ff95681e2 100644
---- a/test/Unit/lit.cfg.py
-+++ b/test/Unit/lit.cfg.py
-@@ -3,6 +3,7 @@
- # Configuration file for the 'lit' test runner.
- 
- import os
-+import platform
- import subprocess
- 
- import lit.formats
-@@ -55,3 +56,26 @@ if sys.platform in ['win32', 'cygwin'] and os.path.isdir(config.shlibdir):
- # Win32 may use %SYSTEMDRIVE% during file system shell operations, so propogate.
- if sys.platform == 'win32' and 'SYSTEMDRIVE' in os.environ:
-     config.environment['SYSTEMDRIVE'] = os.environ['SYSTEMDRIVE']
-+
-+# Add the LLVM dynamic libs to the platform-specific loader search path env var:
-+#
-+# TODO: this is copied from `clang`'s `lit.cfg.py`; should unify..
-+def find_shlibpath_var():
-+    if platform.system() in ['Linux', 'FreeBSD', 'NetBSD', 'OpenBSD', 'SunOS']:
-+        yield 'LD_LIBRARY_PATH'
-+    elif platform.system() == 'Darwin':
-+        yield 'DYLD_LIBRARY_PATH'
-+    elif platform.system() == 'Windows':
-+        yield 'PATH'
-+    elif platform.system() == 'AIX':
-+        yield 'LIBPATH'
-+
-+for shlibpath_var in find_shlibpath_var():
-+    shlibpath = os.path.pathsep.join(
-+        (config.shlibdir,
-+         config.environment.get(shlibpath_var, '')))
-+    config.environment[shlibpath_var] = shlibpath
-+    break
-+else:
-+    lit_config.warning("unable to inject shared library path on '{}'"
-+                       .format(platform.system()))
-diff --git a/test/lit.cfg.py b/test/lit.cfg.py
-index 75a38b4c5dad..856fc75c9d74 100644
---- a/test/lit.cfg.py
-+++ b/test/lit.cfg.py
-@@ -42,6 +42,26 @@ llvm_config.with_environment('PATH', config.llvm_tools_dir, append_path=True)
- llvm_config.with_system_environment(
-     ['HOME', 'INCLUDE', 'LIB', 'TMP', 'TEMP'])
- 
-+# Add the LLVM dynamic libs to the platform-specific loader search path env var:
-+#
-+# TODO: this is copied from `clang`'s `lit.cfg.py`; should unify..
-+def find_shlibpath_var():
-+    if platform.system() in ['Linux', 'FreeBSD', 'NetBSD', 'OpenBSD', 'SunOS']:
-+        yield 'LD_LIBRARY_PATH'
-+    elif platform.system() == 'Darwin':
-+        yield 'DYLD_LIBRARY_PATH'
-+    elif platform.system() == 'Windows':
-+        yield 'PATH'
-+    elif platform.system() == 'AIX':
-+        yield 'LIBPATH'
-+
-+for shlibpath_var in find_shlibpath_var():
-+    shlibpath = config.llvm_shlib_dir
-+    llvm_config.with_environment(shlibpath_var, shlibpath, append_path = True)
-+    break
-+else:
-+    lit_config.warning("unable to inject shared library path on '{}'"
-+                       .format(platform.system()))
- 
- # Set up OCAMLPATH to include newly built OCaml libraries.
- top_ocaml_lib = os.path.join(config.llvm_lib_dir, 'ocaml')
-@@ -318,7 +338,7 @@ def have_cxx_shared_library():
- 
-     try:
-         readobj_cmd = subprocess.Popen(
--            [readobj_exe, '--needed-libs', readobj_exe], stdout=subprocess.PIPE)
-+            [readobj_exe, '--needed-libs', readobj_exe], stdout=subprocess.PIPE, env=config.environment)
-     except OSError:
-         print('could not exec llvm-readobj')
-         return False
diff --git a/llvm/default.nix b/llvm/default.nix
deleted file mode 100644
index 3602c84ea4..0000000000
--- a/llvm/default.nix
+++ /dev/null
@@ -1,87 +0,0 @@
-{
-  lib,
-  stdenv,
-  callPackage,
-  fetchFromGitHub,
-  cmake,
-  ninja,
-  python3,
-  libffi,
-  libxml2,
-  ncurses,
-  zlib,
-  runCommand,
-}: let
-  version = "15.0.7";
-
-  src = fetchFromGitHub {
-    owner = "llvm";
-    repo = "llvm-project";
-    rev = "llvmorg-${version}";
-    sha256 = "sha256-wjuZQyXQ/jsmvy6y1aksCcEDXGBjuhpgngF3XQJ/T4s=";
-  };
-
-  llvm_meta = {
-    license = lib.licenses.ncsa;
-    platforms = lib.platforms.unix;
-  };
-
-  getVersionFile = p: ./15 + "/${p}";
-
-  # Build LLVM first (provides libllvm and llvm-tblgen)
-  libllvm = callPackage ./15/llvm {
-    inherit
-      lib
-      stdenv
-      cmake
-      ninja
-      python3
-      libffi
-      libxml2
-      ncurses
-      zlib
-      runCommand
-      src
-      version
-      llvm_meta
-      getVersionFile
-      ;
-  };
-
-  clang-unwrapped = callPackage ./15/clang {
-    inherit
-      lib
-      stdenv
-      cmake
-      ninja
-      python3
-      libxml2
-      runCommand
-      libllvm
-      src
-      version
-      llvm_meta
-      getVersionFile
-      ;
-  };
-
-  lld = callPackage ./15/lld {
-    inherit
-      lib
-      stdenv
-      cmake
-      ninja
-      libxml2
-      libllvm
-      runCommand
-      src
-      version
-      llvm_meta
-      getVersionFile
-      ;
-  };
-in {
-  llvm_15 = libllvm;
-  lld_15 = lld;
-  llvmPackages_15 = {clang-unwrapped = clang-unwrapped;};
-}