diff --git a/.evergreen/config.yml b/.evergreen/config.yml
index 287058bd02d..b3a5b5462a4 100644
--- a/.evergreen/config.yml
+++ b/.evergreen/config.yml
@@ -436,6 +436,33 @@ functions:
             -p 8100 \
             -v \
             --fault revoked
+  run custom csfle tests:
+    - command: shell.exec
+      type: test
+      params:
+        silent: true
+        working_dir: src
+        script: |
+          cat <<EOT > prepare_client_encryption.sh
+          export CLIENT_ENCRYPTION=${CLIENT_ENCRYPTION}
+          export CSFLE_KMS_PROVIDERS='${CSFLE_KMS_PROVIDERS}'
+          export AWS_ACCESS_KEY_ID="${AWS_ACCESS_KEY_ID}"
+          export AWS_SECRET_ACCESS_KEY="${AWS_SECRET_ACCESS_KEY}"
+          EOT
+    - command: shell.exec
+      type: test
+      params:
+        working_dir: src
+        timeout_secs: 60
+        script: |
+          ${PREPARE_SHELL}
+
+          # Disable xtrace (just in case it was accidentally set).
+          set +x
+          . ./prepare_client_encryption.sh
+          rm -f ./prepare_client_encryption.sh
+
+          UNIFIED=${UNIFIED} MONGODB_URI="${MONGODB_URI}" bash ${PROJECT_DIRECTORY}/.evergreen/run-custom-csfle-tests.sh
   upload test results:
     - command: attach.xunit_results
       params:
@@ -1387,6 +1414,18 @@ tasks:
         vars:
           NODE_LTS_NAME: erbium
       - func: run checks
+  - name: run-custom-csfle-tests
+    tags:
+      - run-custom-csfle-tests
+    commands:
+      - func: install dependencies
+        vars:
+          NODE_LTS_NAME: erbium
+      - func: bootstrap mongo-orchestration
+        vars:
+          VERSION: '4.4'
+          TOPOLOGY: server
+      - func: run custom csfle tests
 buildvariants:
   - name: macos-1014-erbium
     display_name: macOS 10.14 Node Erbium
@@ -1468,12 +1507,6 @@ buildvariants:
       - test-4.4-ocsp-soft-fail
       - test-4.4-ocsp-malicious-invalid-cert-mustStaple-server-does-not-staple
       - test-4.4-ocsp-malicious-no-responder-mustStaple-server-does-not-staple
-  - name: macos-1014-fermium
-    display_name: macOS 10.14 Node Fermium
-    run_on: macos-1014
-    expansions:
-      NODE_LTS_NAME: fermium
-    tasks: *ref_0
   - name: macos-1014-dubnium
     display_name: macOS 10.14 Node Dubnium
     run_on: macos-1014
@@ -1578,12 +1611,6 @@ buildvariants:
       - test-4.4-ocsp-soft-fail
       - test-4.4-ocsp-malicious-invalid-cert-mustStaple-server-does-not-staple
       - test-4.4-ocsp-malicious-no-responder-mustStaple-server-does-not-staple
-  - name: rhel70-fermium
-    display_name: RHEL 7.0 Node Fermium
-    run_on: rhel70-small
-    expansions:
-      NODE_LTS_NAME: fermium
-    tasks: *ref_1
   - name: rhel70-dubnium
     display_name: RHEL 7.0 Node Dubnium
     run_on: rhel70-small
@@ -1654,12 +1681,6 @@ buildvariants:
       - test-auth-kerberos-legacy
       - test-auth-kerberos-unified
       - test-auth-ldap
-  - name: ubuntu-14.04-fermium
-    display_name: Ubuntu 14.04 Node Fermium
-    run_on: ubuntu1404-test
-    expansions:
-      NODE_LTS_NAME: fermium
-    tasks: *ref_2
   - name: ubuntu-14.04-dubnium
     display_name: Ubuntu 14.04 Node Dubnium
     run_on: ubuntu1404-test
@@ -1753,13 +1774,6 @@ buildvariants:
       - test-4.4-ocsp-soft-fail
       - test-4.4-ocsp-malicious-invalid-cert-mustStaple-server-does-not-staple
       - test-4.4-ocsp-malicious-no-responder-mustStaple-server-does-not-staple
-  - name: ubuntu-18.04-fermium
-    display_name: Ubuntu 18.04 Node Fermium
-    run_on: ubuntu1804-test
-    expansions:
-      NODE_LTS_NAME: fermium
-      CLIENT_ENCRYPTION: true
-    tasks: *ref_3
   - name: ubuntu-18.04-dubnium
     display_name: Ubuntu 18.04 Node Dubnium
     run_on: ubuntu1804-test
@@ -1852,13 +1866,6 @@ buildvariants:
       NODE_LTS_NAME: argon
       MSVS_VERSION: 2013
     tasks: *ref_4
-  - name: windows-64-vs2015-fermium
-    display_name: Windows (VS2015) Node Fermium
-    run_on: windows-64-vs2015-large
-    expansions:
-      NODE_LTS_NAME: fermium
-      MSVS_VERSION: 2015
-    tasks: *ref_4
   - name: windows-64-vs2015-erbium
     display_name: Windows (VS2015) Node Erbium
     run_on: windows-64-vs2015-large
@@ -1894,13 +1901,6 @@ buildvariants:
       NODE_LTS_NAME: argon
       MSVS_VERSION: 2015
     tasks: *ref_4
-  - name: windows-64-vs2017-fermium
-    display_name: Windows (VS2017) Node Fermium
-    run_on: windows-64-vs2017-large
-    expansions:
-      NODE_LTS_NAME: fermium
-      MSVS_VERSION: 2017
-    tasks: *ref_4
   - name: windows-64-vs2017-erbium
     display_name: Windows (VS2017) Node Erbium
     run_on: windows-64-vs2017-large
@@ -1941,6 +1941,11 @@ buildvariants:
     run_on: rhel70
     tasks:
       - run-checks
+  - name: ubuntu1804-custom-csfle-tests
+    display_name: Custom FLE Test
+    run_on: ubuntu1804-test
+    tasks:
+      - run-custom-csfle-tests
   - name: ubuntu1804-test-mongodb-aws
     display_name: MONGODB-AWS Auth test
     run_on: ubuntu1804-test
diff --git a/.evergreen/config.yml.in b/.evergreen/config.yml.in
index fc2e7581e28..ea2a8b9ec5f 100644
--- a/.evergreen/config.yml.in
+++ b/.evergreen/config.yml.in
@@ -195,7 +195,7 @@ functions:
             bash ${PROJECT_DIRECTORY}/.evergreen/install-dependencies.sh
     - command: expansions.update
       params:
-        file: src/deps-expansion.yml          
+        file: src/deps-expansion.yml
 
   "run atlas tests":
     - command: shell.exec
@@ -476,6 +476,37 @@ functions:
             -v \
             --fault revoked
 
+  "run custom csfle tests":
+    - command: shell.exec
+      type: test
+      params:
+        silent: true
+        working_dir: "src"
+        script: |
+          ${PREPARE_SHELL}
+          cat <<EOT > prepare_client_encryption.sh
+          export CLIENT_ENCRYPTION=${CLIENT_ENCRYPTION}
+          export CSFLE_KMS_PROVIDERS='${CSFLE_KMS_PROVIDERS}'
+          export AWS_ACCESS_KEY_ID="${AWS_ACCESS_KEY_ID}"
+          export AWS_SECRET_ACCESS_KEY="${AWS_SECRET_ACCESS_KEY}"
+          export CSFLE_GIT_REF="${CSFLE_GIT_REF}"
+          export CDRIVER_GIT_REF="${CDRIVER_GIT_REF}"
+          EOT
+    - command: shell.exec
+      type: test
+      params:
+        working_dir: "src"
+        timeout_secs: 60
+        script: |
+          ${PREPARE_SHELL}
+
+          # Disable xtrace (just in case it was accidentally set).
+          set +x
+          . ./prepare_client_encryption.sh
+          rm -f ./prepare_client_encryption.sh
+
+          UNIFIED=${UNIFIED} MONGODB_URI="${MONGODB_URI}" bash ${PROJECT_DIRECTORY}/.evergreen/run-custom-csfle-tests.sh
+
   "upload test results":
     - command: attach.xunit_results
       params:
diff --git a/.evergreen/generate_evergreen_tasks.js b/.evergreen/generate_evergreen_tasks.js
index 1b52adcfe3f..192174ceec9 100644
--- a/.evergreen/generate_evergreen_tasks.js
+++ b/.evergreen/generate_evergreen_tasks.js
@@ -410,11 +410,37 @@ SINGLETON_TASKS.push({
   ]
 });
 
+SINGLETON_TASKS.push({
+  name: 'run-custom-csfle-tests',
+  tags: ['run-custom-csfle-tests'],
+  commands: [
+    {
+      func: 'install dependencies',
+      vars: {
+        NODE_LTS_NAME: 'erbium',
+      },
+    },
+    {
+      func: 'bootstrap mongo-orchestration',
+      vars: {
+        VERSION: '4.4',
+        TOPOLOGY: 'server'
+      }
+    },
+    { func: 'run custom csfle tests' }
+  ]
+});
+
 BUILD_VARIANTS.push({
   name: 'lint',
   display_name: 'lint',
   run_on: 'rhel70',
   tasks: ['run-checks']
+}, {
+  name: 'ubuntu1804-custom-csfle-tests',
+  display_name: 'Custom FLE Version Test',
+  run_on: 'ubuntu1804-test',
+  tasks: ['run-custom-csfle-tests']
 });
 
 // special case for MONGODB-AWS authentication
diff --git a/.evergreen/run-custom-csfle-tests.sh b/.evergreen/run-custom-csfle-tests.sh
new file mode 100644
index 00000000000..2571e68d9ca
--- /dev/null
+++ b/.evergreen/run-custom-csfle-tests.sh
@@ -0,0 +1,52 @@
+#! /usr/bin/env bash
+
+# Initiail checks for running these tests
+if [ -z ${AWS_ACCESS_KEY_ID+omitted} ]; then echo "AWS_ACCESS_KEY_ID is unset" && exit 1; fi
+if [ -z ${AWS_SECRET_ACCESS_KEY+omitted} ]; then echo "AWS_SECRET_ACCESS_KEY is unset" && exit 1; fi
+if [ -z ${CSFLE_KMS_PROVIDERS+omitted} ]; then echo "CSFLE_KMS_PROVIDERS is unset" && exit 1; fi
+
+[ -s "$PROJECT_DIRECTORY/node-artifacts/nvm/nvm.sh" ] && source "$PROJECT_DIRECTORY"/node-artifacts/nvm/nvm.sh
+
+set -o xtrace   # Write all commands first to stderr
+set -o errexit  # Exit the script with error if any of the commands fail
+
+# Environment Variables:
+# CSFLE_GIT_REF - set the git reference to checkout for a custom CSFLE version
+# CDRIVER_GIT_REF - set the git reference to checkout for a custom CDRIVER version (this is for libbson)
+
+CSFLE_GIT_REF=${CSFLE_GIT_REF:-master}
+CDRIVER_GIT_REF=${CDRIVER_GIT_REF:-1.17.4}
+
+rm -rf csfle-deps-tmp
+mkdir -p csfle-deps-tmp
+pushd csfle-deps-tmp
+
+rm -rf libmongocrypt mongo-c-driver
+
+git clone https://github.com/mongodb/libmongocrypt.git
+pushd libmongocrypt
+git fetch --tags
+git checkout "$CSFLE_GIT_REF" -b csfle-custom
+popd # libmongocrypt
+
+git clone https://github.com/mongodb/mongo-c-driver.git
+pushd mongo-c-driver
+git fetch --tags
+git checkout "$CDRIVER_GIT_REF" -b cdriver-custom
+popd # mongo-c-driver
+
+pushd libmongocrypt/bindings/node
+
+source ./.evergreen/find_cmake.sh
+bash ./etc/build-static.sh
+
+popd # libmongocrypt/bindings/node
+popd # csfle-deps-tmp
+
+npm install
+
+cp -r csfle-deps-tmp/libmongocrypt/bindings/node node_modules/mongodb-client-encryption
+
+export MONGODB_UNIFIED_TOPOLOGY=${UNIFIED}
+export MONGODB_URI=${MONGODB_URI}
+npx mocha test/functional/client_side_encryption