diff --git a/ci3/memsuspend_limit b/ci3/memsuspend_limit
new file mode 100755
index 000000000000..12e16e70c55f
--- /dev/null
+++ b/ci3/memsuspend_limit
@@ -0,0 +1,26 @@
+#!/bin/bash
+set -eu
+
+# Get the hardware memory in GB, useful for setting the memsuspend limit.
+# General rule of thumb:
+# - Allocate 1/4 of total hardware memory for the build.
+# - Max out at 64GB
+if [ -n "${MEMSUSPEND:-}" ]; then
+  echo $MEMSUSPEND
+  exit
+fi
+os=$(uname -s)
+total_mem_gb=64 # Default to 64GB
+
+if [[ "$os" == "Darwin" ]]; then
+  total_mem_bytes=$(sysctl -n hw.memsize)
+  total_mem_gb=$((total_mem_bytes / 1024 / 1024 / 1024))
+elif [[ "$os" == "Linux" ]]; then
+  total_mem_gb=$(free -g | awk '/^Mem:/ {print $2}')
+fi
+
+# Allocate 1/4 of total hardware memory for the build.
+total_mem_gb=$((total_mem_gb / 4))
+
+# Max out at 64GB
+echo $(( total_mem_gb < 64 ? total_mem_gb : 64 ))G
diff --git a/ci3/parallelise b/ci3/parallelise
index 5fde397e88c9..9c27140d7b7f 100755
--- a/ci3/parallelise
+++ b/ci3/parallelise
@@ -5,7 +5,7 @@ NO_CD=1 source $(git rev-parse --show-toplevel)/ci3/source
 
 cd $root
 jobs=$(get_num_cpus_max ${1:-})
-parallel_args="-j$jobs --memsuspend ${MEMSUSPEND:-64G} --line-buffer --joblog joblog.txt"
+parallel_args="-j$jobs --memsuspend $(memsuspend_limit) --line-buffer --joblog joblog.txt"
 
 # If not in CI, fail fast.
 if [ "$CI" -eq 0 ]; then
diff --git a/noir-projects/noir-contracts/bootstrap.sh b/noir-projects/noir-contracts/bootstrap.sh
index 57a6900e2c53..790043591cdf 100755
--- a/noir-projects/noir-contracts/bootstrap.sh
+++ b/noir-projects/noir-contracts/bootstrap.sh
@@ -39,7 +39,7 @@ trap on_exit EXIT
 mkdir -p $tmp_dir
 
 # Set common flags for parallel.
-export PARALLEL_FLAGS="-j${PARALLELISM:-16} --halt now,fail=1 --memsuspend ${MEMSUSPEND:-64G}"
+export PARALLEL_FLAGS="-j${PARALLELISM:-16} --halt now,fail=1 --memsuspend $(memsuspend_limit)"
 
 # This computes a vk and adds it to the input function json if it's private, else returns same input.
 # stdin has the function json.
diff --git a/noir-projects/noir-protocol-circuits/bootstrap.sh b/noir-projects/noir-protocol-circuits/bootstrap.sh
index 668dcde7b7d3..7bc5f830fae1 100755
--- a/noir-projects/noir-protocol-circuits/bootstrap.sh
+++ b/noir-projects/noir-protocol-circuits/bootstrap.sh
@@ -157,7 +157,7 @@ function build {
           echo "$(basename $dir)"
       fi
     done | \
-    parallel -v --line-buffer --tag --halt now,fail=1 --memsuspend ${MEMSUSPEND:-64G} \
+    parallel -v --line-buffer --tag --halt now,fail=1 --memsuspend $(memsuspend_limit) \
       --joblog joblog.txt compile {}
   code=$?
   cat joblog.txt