diff --git a/ci/build.yml b/ci/build.yml
index 9a323bf3b..ff9baa6af 100644
--- a/ci/build.yml
+++ b/ci/build.yml
@@ -4,11 +4,35 @@ variables:
   SDL_VIDEODRIVER: "dummy"
   XDG_RUNTIME_DIR: "/var/tmp"
 
+.only_changes_core: &only_changes_core
+  only:
+    changes:
+      - ci/**/*
+      - common/**/*
+      - core/**/*
+      - crypto/**/*
+      - python/**/*
+      - storage/**/*
+      - tools/**/*
+      - vendor/**/*
+
+.only_changes_legacy: &only_changes_legacy
+  only:
+    changes:
+      - ci/**/*
+      - common/**/*
+      - crypto/**/*
+      - legacy/**/*
+      - python/**/*
+      - storage/**/*
+      - tools/**/*
+      - vendor/**/*
 
 # Core
 
 build core firmware regular:
   stage: build
+  <<: *only_changes_core
   script:
     - cd core
     - pipenv run make build_cross
@@ -28,6 +52,7 @@ build core firmware regular:
 
 build core firmware bitcoinonly:
   stage: build
+  <<: *only_changes_core
   variables:
     BITCOIN_ONLY: "1"
   script:
@@ -46,12 +71,14 @@ build core firmware bitcoinonly:
 
 build core unix regular:
   stage: build
+  <<: *only_changes_core
   script:
     - cd core
     - pipenv run make build_unix
 
 build core unix frozen regular:
   stage: build
+  <<: *only_changes_core
   script:
     - cd core
     - pipenv run make build_unix_frozen
@@ -64,6 +91,7 @@ build core unix frozen regular:
 
 build core unix frozen bitcoinonly:
   stage: build
+  <<: *only_changes_core
   variables:
     BITCOIN_ONLY: "1"
   script:
@@ -79,6 +107,7 @@ build core unix frozen bitcoinonly:
 
 build core unix frozen debug:
   stage: build
+  <<: *only_changes_core
   variables:
     PYOPT: "0"
   script:
@@ -94,6 +123,10 @@ build core unix frozen debug:
 
 build crypto:
   stage: build
+  only:
+    changes:
+      - ci/**/*
+      - crypto/**/*
   script:
     - cd crypto
     - pipenv run make
@@ -112,6 +145,7 @@ build crypto:
 # TODO: add clang https://github.com/trezor/trezor-firmware/issues/44
 build legacy firmware regular:
   stage: build
+  <<: *only_changes_legacy
   variables:
     MEMORY_PROTECT: "0"
   script:
@@ -130,6 +164,7 @@ build legacy firmware regular:
 
 build legacy firmware debug:
   stage: build
+  <<: *only_changes_legacy
   variables:
     DEBUG_LINK: "1"
     MEMORY_PROTECT: "0"
@@ -139,6 +174,7 @@ build legacy firmware debug:
 
 build legacy firmware bitcoinonly:
   stage: build
+  <<: *only_changes_legacy
   variables:
     BITCOIN_ONLY: "1"
     MEMORY_PROTECT: "0"
@@ -158,6 +194,7 @@ build legacy firmware bitcoinonly:
 
 build legacy emu regular:
   stage: build
+  <<: *only_changes_legacy
   variables:
     DEBUG_LINK: "1"
     EMULATOR: "1"
@@ -172,6 +209,7 @@ build legacy emu regular:
 
 build legacy emu bitcoinonly:
   stage: build
+  <<: *only_changes_legacy
   variables:
     BITCOIN_ONLY: "1"
     DEBUG_LINK: "1"
diff --git a/ci/prebuild.yml b/ci/prebuild.yml
index 8fa9c04f2..b3e50fcc8 100644
--- a/ci/prebuild.yml
+++ b/ci/prebuild.yml
@@ -2,15 +2,34 @@ image: registry.gitlab.com/satoshilabs/trezor/trezor-firmware/environment
 
 prebuild style:
   stage: prebuild
+  only:
+    changes:
+      - ci/**/*
+      - "**/*.c"
+      - "**/*.h"
+      - "**/*.py"
   script:
     - pipenv run make style_check
 
 prebuild common:
   stage: prebuild
+  only:
+    changes:
+      - ci/**/*
+      - "**/*.json"
+      - "**/*.proto"
   script:
     - pipenv run make defs_check
 
 prebuild gen:
   stage: prebuild
+  only:
+    changes:
+      - ci/**/*
+      - "**/*.c"
+      - "**/*.h"
+      - "**/*.json"
+      - "**/*.proto"
+      - "**/*.py"
   script:
     - pipenv run make gen_check
diff --git a/ci/test.yml b/ci/test.yml
index 4c525609b..a25a80efa 100644
--- a/ci/test.yml
+++ b/ci/test.yml
@@ -1,9 +1,36 @@
 image: registry.gitlab.com/satoshilabs/trezor/trezor-firmware/environment
 
+.only_changes_core: &only_changes_core
+  only:
+    changes:
+      - ci/**/*
+      - common/**/*
+      - core/**/*
+      - crypto/**/*
+      - python/**/*
+      - storage/**/*
+      - tests/**/*
+      - tools/**/*
+      - vendor/**/*
+
+.only_changes_legacy: &only_changes_legacy
+  only:
+    changes:
+      - ci/**/*
+      - common/**/*
+      - crypto/**/*
+      - legacy/**/*
+      - python/**/*
+      - storage/**/*
+      - tests/**/*
+      - tools/**/*
+      - vendor/**/*
+
 # Core
 
 test core unix unit:
   stage: test
+  <<: *only_changes_core
   dependencies:
     - build core unix frozen regular
   script:
@@ -12,6 +39,7 @@ test core unix unit:
 
 test core unix device:
   stage: test
+  <<: *only_changes_core
   dependencies:
     - build core unix frozen regular
   script:
@@ -20,6 +48,7 @@ test core unix device:
 
 test core unix device bitcoinonly:
   stage: test
+  <<: *only_changes_core
   dependencies:
     - build core unix frozen bitcoinonly
   variables:
@@ -31,6 +60,7 @@ test core unix device bitcoinonly:
 
 test core unix monero:
   stage: test
+  <<: *only_changes_core
   dependencies:
     - build core unix frozen regular
   script:
@@ -42,6 +72,10 @@ test core unix monero:
 
 test crypto:
   stage: test
+  only:
+    changes:
+      - ci/**/*
+      - crypto/**/*
   dependencies:
     - build crypto
   script:
@@ -57,6 +91,7 @@ test crypto:
 
 test legacy emu:
   stage: test
+  <<: *only_changes_legacy
   dependencies:
     - build legacy emu regular
   variables:
@@ -67,6 +102,7 @@ test legacy emu:
 
 test legacy emu bitcoinonly:
   stage: test
+  <<: *only_changes_legacy
   dependencies:
     - build legacy emu bitcoinonly
   variables:
@@ -82,6 +118,10 @@ test legacy emu bitcoinonly:
 
 test python:
   stage: test
+  only:
+    changes:
+      - ci/**/*
+      - python/**/*
   script:
     - cd python
     - pipenv run tox
@@ -91,6 +131,10 @@ test python:
 
 test storage:
   stage: test
+  only:
+    changes:
+      - ci/**/*
+      - storage/**/*
   dependencies: []
   script:
     - cd storage/tests
@@ -102,6 +146,8 @@ test storage:
 
 test upgrade:
   stage: test
+  <<: *only_changes_core
+  <<: *only_changes_legacy
   dependencies:
     - build core unix frozen debug
     - build legacy emu regular