diff --git a/tools/checkpoints.patch b/tools/checkpoints.patch
new file mode 100644
index 0000000..daedec9
--- /dev/null
+++ b/tools/checkpoints.patch
@@ -0,0 +1,43 @@
+From 25b581c833679939408fa51ce1d43b55ae481d51 Mon Sep 17 00:00:00 2001
+From: Jeremy Rand <jeremyrand@airmail.cc>
+Date: Fri, 19 Feb 2021 00:23:40 +0000
+Subject: [PATCH] clang: Support rbm checkpointing
+
+---
+ projects/clang/build | 13 +++++++++++++
+ 1 file changed, 13 insertions(+)
+
+diff --git a/projects/clang/build b/projects/clang/build
+index c4c16d9..bb8283b 100644
+--- a/projects/clang/build
++++ b/projects/clang/build
+@@ -2,6 +2,13 @@
+ [% c("var/set_default_env") -%]
+ distdir=/var/tmp/dist/[% project %]
+ mkdir -p /var/tmp/dist
++
++if [[ -e /var/tmp/dist/checkpoint1 ]] ; then
++  set +e
++  source /var/tmp/dist/checkpoint1
++  set -e
++else
++
+ tar -C /var/tmp/dist -xf [% c('input_files_by_name/cmake') %]
+ export PATH="/var/tmp/dist/cmake/bin:$PATH"
+ [% IF c("var/linux") || c("var/android") %]
+@@ -35,6 +42,12 @@ cd build
+             [% IF c("var/rlbox") -%]-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly \[% END -%]
+                                     -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;compiler-rt;libcxx;libcxxabi;lld"
+ [% END -%]
++
++set > /var/tmp/dist/checkpoint1
++export -p >> /var/tmp/dist/checkpoint1
++fi
++
++cd /var/tmp/build/clang-source/build
+ make -j[% c("buildconf/num_procs") %]
+ make install
+ cd /var/tmp/dist
+-- 
+2.20.1
+