diff --git a/.circleci/config.yml b/.circleci/config.yml
index 189927694f601..40b489b8ce012 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -142,6 +142,10 @@ commands:
             cd ~/emsdk
             ./emsdk install tot
             ./emsdk activate tot
+            # Write the version of clang into a file for use in the ccache key
+            ./upstream/bin/clang --version > clang_version.txt
+            echo "clang version:"
+            cat ~/emsdk/clang_version.txt
             # Remove the emsdk version of emscripten to save space in the
             # persistent workspace and to avoid any confusion with the version
             # we are trying to test.
@@ -171,7 +175,7 @@ commands:
           command: |
             ./emcc --clear-cache
       - pip-install
-      - run: apt-get install -q -y ninja-build
+      - run: apt-get install -q -y ninja-build ccache
       - run:
           name: embuilder build ALL
           command: |
@@ -196,6 +200,12 @@ commands:
           command: |
             ./embuilder build MINIMAL --pic --lto
             ./test/runner test_hello_world
+      - run:
+          name: "Ccache stats"
+          command: |
+            ccache --print-stats
+            ccache --zero-stats
+
   persist:
     description: "Persist the emsdk, libraries, and engines"
     steps:
@@ -209,6 +219,19 @@ commands:
             - vms/
             - wasi-sdk/
             - .jsvu/
+      - when:
+          # Only the main branch will store its cache results, and only the non-main branches
+          # will use cached results. This prevents untrusted PRs from polluting caches used
+          # by other branches.
+          condition:
+            equal: [ "main", << pipeline.git.branch >> ]
+          steps:
+            - save_cache:
+                name: "Save Ccache cache"
+                paths:
+                  - ~/.ccache
+                key: clang-{{ checksum "~/emsdk/clang_version.txt" }}
+
   prepare-for-tests:
     description: "Setup emscripten tests"
     steps:
@@ -543,6 +566,7 @@ jobs:
     environment:
       EMCC_CORES: 16
       EMCC_USE_NINJA: 1
+      EM_COMPILER_WRAPPER: "ccache"
     steps:
       - checkout
       - run:
@@ -570,6 +594,14 @@ jobs:
             tar xvf wasi-sysroot-11.0.tar.gz -C ~/wasi-sdk/
       - install-v8
       - install-emsdk
+      - when:
+          condition:
+            not:
+              equal: [ "main", << pipeline.git.branch >> ]
+          steps:
+            - restore_cache:
+                name: "Restore Ccache cache"
+                key: clang-{{ checksum "~/emsdk/clang_version.txt" }}
       - build-libs
       - run:
           name: Clean build directory