diff --git a/.circleci/config.yml b/.circleci/config.yml
index 1dff3ba719..86da321dd3 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -55,7 +55,7 @@ commands:
       - run:
           name: "Install apt dependencies"
           command: |
-            echo 'deb https://apt.llvm.org/buster/ llvm-toolchain-buster-<<parameters.llvm>> main' > /etc/apt/sources.list.d/llvm.list
+            echo 'deb https://apt.llvm.org/bullseye/ llvm-toolchain-bullseye-<<parameters.llvm>> main' > /etc/apt/sources.list.d/llvm.list
             wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
             apt-get update
             apt-get install --no-install-recommends -y \
@@ -100,11 +100,18 @@ commands:
 jobs:
   test-llvm14-go118:
     docker:
-      - image: golang:1.18-buster
+      - image: golang:1.18-bullseye
     steps:
       - test-linux:
           llvm: "14"
     resource_class: large
+  test-llvm17-go121:
+    docker:
+      - image: golang:1.21-bullseye
+    steps:
+      - test-linux:
+          llvm: "17"
+    resource_class: large
 
 workflows:
   test-all:
@@ -112,3 +119,5 @@ workflows:
       # This tests our lowest supported versions of Go and LLVM, to make sure at
       # least the smoke tests still pass.
       - test-llvm14-go118
+      # This tests the upcoming LLVM 17 support.
+      - test-llvm17-go121
diff --git a/.github/workflows/build-macos.yml b/.github/workflows/build-macos.yml
index 1284a4edd3..ccfd73f861 100644
--- a/.github/workflows/build-macos.yml
+++ b/.github/workflows/build-macos.yml
@@ -116,11 +116,18 @@ jobs:
   test-macos-homebrew:
     name: homebrew-install
     runs-on: macos-latest
+    strategy:
+      matrix:
+        version: [16, 17]
     steps:
+      - name: test
+        if: matrix.version == 16
+        run: echo default LLVM
+      - name: Update Homebrew
+        run: brew update
       - name: Install LLVM
-        shell: bash
         run: |
-          HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@16
+          HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@${{ matrix.version }}
       - name: Checkout
         uses: actions/checkout@v3
       - name: Install Go
@@ -128,7 +135,13 @@ jobs:
         with:
           go-version: '1.21'
           cache: true
-      - name: Build TinyGo
+      - name: Build TinyGo (LLVM ${{ matrix.version }})
+        run: go install -tags=llvm${{ matrix.version }}
+      - name: Check binary
+        run: tinygo version
+      - name: Build TinyGo (default LLVM)
+        if: ${{ matrix.version }} == '16'
         run: go install
       - name: Check binary
+        if: ${{ matrix.version }} == '16'
         run: tinygo version
diff --git a/cgo/libclang_config_llvm16.go b/cgo/libclang_config_llvm16.go
index 79aacd2f26..28091701dc 100644
--- a/cgo/libclang_config_llvm16.go
+++ b/cgo/libclang_config_llvm16.go
@@ -1,4 +1,4 @@
-//go:build !byollvm && !llvm14 && !llvm15
+//go:build !byollvm && !llvm14 && !llvm15 && !llvm17
 
 package cgo
 
diff --git a/cgo/libclang_config_llvm17.go b/cgo/libclang_config_llvm17.go
new file mode 100644
index 0000000000..fd6d1480e3
--- /dev/null
+++ b/cgo/libclang_config_llvm17.go
@@ -0,0 +1,15 @@
+//go:build !byollvm && llvm17
+
+package cgo
+
+/*
+#cgo linux        CFLAGS:  -I/usr/include/llvm-17 -I/usr/include/llvm-c-17 -I/usr/lib/llvm-17/include
+#cgo darwin,amd64 CFLAGS:  -I/usr/local/opt/llvm@17/include
+#cgo darwin,arm64 CFLAGS:  -I/opt/homebrew/opt/llvm@17/include
+#cgo freebsd      CFLAGS:  -I/usr/local/llvm17/include
+#cgo linux        LDFLAGS: -L/usr/lib/llvm-17/lib -lclang
+#cgo darwin,amd64 LDFLAGS: -L/usr/local/opt/llvm@17/lib -lclang -lffi
+#cgo darwin,arm64 LDFLAGS: -L/opt/homebrew/opt/llvm@17/lib -lclang -lffi
+#cgo freebsd      LDFLAGS: -L/usr/local/llvm17/lib -lclang
+*/
+import "C"
diff --git a/go.mod b/go.mod
index 48049c88ef..36d601f882 100644
--- a/go.mod
+++ b/go.mod
@@ -18,7 +18,7 @@ require (
 	golang.org/x/sys v0.11.0
 	golang.org/x/tools v0.12.0
 	gopkg.in/yaml.v2 v2.4.0
-	tinygo.org/x/go-llvm v0.0.0-20230920233244-32ed56c6be9c
+	tinygo.org/x/go-llvm v0.0.0-20230923132128-bba3c7009bfd
 )
 
 require (
diff --git a/go.sum b/go.sum
index b895ee1d8c..1b5ad074be 100644
--- a/go.sum
+++ b/go.sum
@@ -65,5 +65,5 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
-tinygo.org/x/go-llvm v0.0.0-20230920233244-32ed56c6be9c h1:rS8mAFqf0CfxPCbtfsI3bWL4jkb0TBYA1wx7tY1nu28=
-tinygo.org/x/go-llvm v0.0.0-20230920233244-32ed56c6be9c/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
+tinygo.org/x/go-llvm v0.0.0-20230923132128-bba3c7009bfd h1:iSVvs8r3ooxYTsmcf7FKCHq83eOSUkWKtmQhnDadDQU=
+tinygo.org/x/go-llvm v0.0.0-20230923132128-bba3c7009bfd/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=