diff --git a/.azure/linux-stack.yml b/.azure/linux-stack.yml
index a7e636913..5b88f37b4 100644
--- a/.azure/linux-stack.yml
+++ b/.azure/linux-stack.yml
@@ -25,13 +25,30 @@ jobs:
         YAML_FILE: stack-8.4.2.yaml
       stack-8.2.2:
         YAML_FILE: stack-8.2.2.yaml
+  variables:
+    STACK_ROOT: /home/vsts/.stack
   steps:
+  - task: CacheBeta@0
+    inputs:
+      key: |
+        "cache"
+        $(Agent.OS)
+        $(Build.SourcesDirectory)/$(YAML_FILE)
+      path: .azure-cache
+      cacheHitVar: CACHE_RESTORED
+    displayName: "Download cache"
+  - bash: |
+      mkdir -p $STACK_ROOT
+      tar -xzf .azure-cache/stack-root.tar.gz -C /
+      mkdir -p .stack-work
+      tar -xzf .azure-cache/stack-work.tar.gz
+    displayName: "Unpack cache"
+    condition: eq(variables.CACHE_RESTORED, 'true')
   - bash: |
       git submodule sync
       git submodule update --init
     displayName: Sync submodules
   - bash: |
-      export STACK_ROOT="$(Build.SourcesDirectory)"/.stack-root
       mkdir -p ~/.local/bin
       curl -L https://get.haskellstack.org/stable/linux-x86_64.tar.gz | \
         tar xz --wildcards --strip-components=1 -C ~/.local/bin '*/stack'
@@ -66,3 +83,8 @@ jobs:
   #     source .azure/linux.bashrc
   #     stack test --stack-yaml $(YAML_FILE)
   #   displayName: Run Test
+  - bash: |
+      mkdir -p .azure-cache
+      tar -czf .azure-cache/stack-root.tar.gz $STACK_ROOT
+      tar -czf .azure-cache/stack-work.tar.gz .stack-work
+    displayName: "Pack cache"
diff --git a/.azure/macos-stack.yml b/.azure/macos-stack.yml
index 86644471e..fa005842f 100644
--- a/.azure/macos-stack.yml
+++ b/.azure/macos-stack.yml
@@ -21,13 +21,30 @@ jobs:
         YAML_FILE: stack-8.4.2.yaml
       stack-8.2.2:
         YAML_FILE: stack-8.2.2.yaml
+  variables:
+    STACK_ROOT: /Users/vsts/.stack
   steps:
+  - task: CacheBeta@0
+    inputs:
+      key: |
+        "cache"
+        $(Agent.OS)
+        $(Build.SourcesDirectory)/$(YAML_FILE)
+      path: .azure-cache
+      cacheHitVar: CACHE_RESTORED
+    displayName: "Download cache"
+  - bash: |
+      mkdir -p $STACK_ROOT
+      tar -xzf .azure-cache/stack-root.tar.gz -C /
+      mkdir -p .stack-work
+      tar -xzf .azure-cache/stack-work.tar.gz
+    displayName: "Unpack cache"
+    condition: eq(variables.CACHE_RESTORED, 'true')
   - bash: |
       git submodule sync
       git submodule update --init
     displayName: Sync submodules
   - bash: |
-      export STACK_ROOT="$(Build.SourcesDirectory)"/.stack-root
       mkdir -p ~/.local/bin
       curl -skL https://get.haskellstack.org/stable/osx-x86_64.tar.gz | \
         tar xz --strip-components=1 --include '*/stack' -C ~/.local/bin;
@@ -63,3 +80,8 @@ jobs:
   #     source .azure/macos.bashrc
   #     stack test --stack-yaml $(YAML_FILE)
   #   displayName: Run Test
+  - bash: |
+      mkdir -p .azure-cache
+      tar -czf .azure-cache/stack-root.tar.gz $STACK_ROOT
+      tar -czf .azure-cache/stack-work.tar.gz .stack-work
+    displayName: "Pack cache"
diff --git a/.azure/windows-stack.yml b/.azure/windows-stack.yml
index 4187ec03c..1dec036dc 100644
--- a/.azure/windows-stack.yml
+++ b/.azure/windows-stack.yml
@@ -23,7 +23,26 @@ jobs:
         YAML_FILE: stack-8.4.2.yaml
       stack-8.2.2:
         YAML_FILE: stack-8.2.2.yaml
+  variables:
+    STACK_ROOT: "C:\\sr"
+
   steps:
+  - task: CacheBeta@0
+    inputs:
+      key: |
+        "stack-root"
+        $(Agent.OS)
+        $(Build.SourcesDirectory)/$(YAML_FILE)
+      path: $(STACK_ROOT)
+    displayName: "Cache stack-root"
+  - task: CacheBeta@0
+    inputs:
+      key: |
+        "stack-work"
+        $(Agent.OS)
+        $(Build.SourcesDirectory)/$(YAML_FILE)
+      path: .stack-work
+    displayName: "Cache stack-work"
   - bash: |
       git submodule sync
       git submodule update --init
diff --git a/.azure/windows.bashrc b/.azure/windows.bashrc
index 8de96772d..724f2795d 100644
--- a/.azure/windows.bashrc
+++ b/.azure/windows.bashrc
@@ -1,4 +1,3 @@
-export STACK_ROOT="C:\\sr"
 export LOCAL_BIN_PATH=$(cygpath $APPDATA\\local\\bin)
 export Z3_BIN_PATH=/usr/local/z3-4.8.5-x64-win/bin
 export PATH=$Z3_BIN_PATH:$LOCAL_BIN_PATH:$PATH