diff --git a/.gitmodules b/.gitmodules
index 05acbe72d6..c5353516f5 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -31,7 +31,6 @@
 [submodule "waterbox/llvm-project"]
 	path = waterbox/llvm-project
 	url = https://github.com/llvm/llvm-project.git
-	branch = llvmorg-16.0.0
 [submodule "submodules/libdarm"]
 	path = submodules/libdarm
 	url = https://github.com/jbremer/darm.git
diff --git a/waterbox/libcxx/configure-for-waterbox-phase-- b/waterbox/libcxx/configure-for-waterbox-phase--
index 3579fb3b41..51b9406aa5 100755
--- a/waterbox/libcxx/configure-for-waterbox-phase--
+++ b/waterbox/libcxx/configure-for-waterbox-phase--
@@ -30,6 +30,6 @@ cmake \
 	-DCOMPILER_RT_USE_BUILTINS_LIBRARY=ON \
 	-UCOMPILER_RT_BAREMETAL_BUILD \
 	-DCOMPILER_RT_BAREMETAL_BUILD=ON \
-	-DCOMPILER_RT_HAS_FPIC_FLAG=OFF \
+	-DCOMPILER_RT_BUILTINS_ENABLE_PIC=OFF \
 	-DCMAKE_INSTALL_PREFIX="$SYSROOT" \
 	$LLVMDIR/compiler-rt
diff --git a/waterbox/libcxx/configure-for-waterbox-phase-1 b/waterbox/libcxx/configure-for-waterbox-phase-1
index 39899ac473..da5f184bfb 100755
--- a/waterbox/libcxx/configure-for-waterbox-phase-1
+++ b/waterbox/libcxx/configure-for-waterbox-phase-1
@@ -27,6 +27,7 @@ cmake \
 	-DLIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON \
 	-DLIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY=OFF \
 	-DLIBCXX_ENABLE_RANDOM_DEVICE=OFF \
+	-DLIBCXX_ENABLE_TIME_ZONE_DATABASE=OFF \
 	-DLIBCXX_HAS_MUSL_LIBC=ON \
 	-DLIBCXX_USE_COMPILER_RT=ON \
 	-DLIBCXX_INCLUDE_TESTS=OFF \
diff --git a/waterbox/libcxx/configure-for-waterbox-phase-2 b/waterbox/libcxx/configure-for-waterbox-phase-2
index c55128aa19..4bda90081d 100755
--- a/waterbox/libcxx/configure-for-waterbox-phase-2
+++ b/waterbox/libcxx/configure-for-waterbox-phase-2
@@ -15,6 +15,7 @@ export LDFLAGS="-no-pie"
 cmake \
 	-DCMAKE_C_COMPILER="$CC" \
 	-DCMAKE_CXX_COMPILER="$CC" \
+	-DLLVM_ENABLE_RUNTIMES="libunwind" \
 	-DLIBCXXABI_ENABLE_SHARED=OFF \
 	-DLIBCXXABI_BAREMETAL=ON \
 	-DLIBCXXABI_SILENT_TERMINATE=ON \
diff --git a/waterbox/libcxx/setup-llvm.sh b/waterbox/libcxx/setup-llvm.sh
index 33d6850253..d1e9e6f331 100755
--- a/waterbox/libcxx/setup-llvm.sh
+++ b/waterbox/libcxx/setup-llvm.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 set -e
-LLVM_TAG=llvmorg-16.0.0
+LLVM_TAG=llvmorg-18.1.3
 LLVM_DIRS="cmake compiler-rt libunwind libcxx libcxxabi"
 LLVM_PATH=../llvm-project
 LLVM_GIT_DIR=$(git rev-parse --git-path modules/waterbox/llvm-project)
diff --git a/waterbox/llvm-project b/waterbox/llvm-project
index 08d094a0e4..c13b7485b8 160000
--- a/waterbox/llvm-project
+++ b/waterbox/llvm-project
@@ -1 +1 @@
-Subproject commit 08d094a0e457360ad8b94b017d2dc277e697ca76
+Subproject commit c13b7485b87909fcf739f62cfa382b55407433c0