diff --git a/.gitmodules b/.gitmodules
index c809da2..efd5330 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,7 +1,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/llvm/llvm-project
-	branch = release/8.x
+	branch = release/9.x
 [submodule "src/wasi-libc"]
 	path = src/wasi-libc
 	url = https://github.com/CraneStation/wasi-libc
diff --git a/README.md b/README.md
index 3c767dc..53d8340 100644
--- a/README.md
+++ b/README.md
@@ -15,12 +15,13 @@ wasi-libc tree.
 The libc portion of this SDK is the
 [wasi-libc](https://github.com/CraneStation/wasi-libc).
 
-Upstream Clang and LLVM 8.0 can compile for WASI out of the box, and WebAssembly
-support is included in them by default. So, all that's done here is to provide
-builds configured to set the default target and sysroot for convenience.
+Upstream Clang and LLVM (from 8.0 onwards) can compile for WASI out of the box,
+and WebAssembly support is included in them by default. So, all that's done here
+is to provide builds configured to set the default target and sysroot for
+convenience.
 
-One could also use a standard Clang 8.0, build a sysroot from the sources
-mentioned above, and compile with
+One could also use a standard Clang installation, build a sysroot from the
+sources mentioned above, and compile with
 "--target=wasm32-wasi --sysroot=/path/to/sysroot".
 
 ## Notes for Autoconf
diff --git a/src/config b/src/config
index a8d79c3..5256817 160000
--- a/src/config
+++ b/src/config
@@ -1 +1 @@
-Subproject commit a8d79c3130da83c7cacd6fee31b9acc53799c406
+Subproject commit 5256817ace8493502ec88501a19e4051c2e220b0
diff --git a/src/llvm-project b/src/llvm-project
index 0399d5a..c1a0a21 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit 0399d5a9682b3cef71c653373e38890c63c4c365
+Subproject commit c1a0a213378a458fbea1a5c77b315c7dce08fd05
diff --git a/src/wasi-libc b/src/wasi-libc
index f645f49..5933c20 160000
--- a/src/wasi-libc
+++ b/src/wasi-libc
@@ -1 +1 @@
-Subproject commit f645f498dfbbbc00a7a97874d33082d3605c3f21
+Subproject commit 5933c205df976a9da0468802f164e5bb4f061b11