diff --git a/jank-build/README.md b/jank-build/README.md
new file mode 100644
index 0000000..4245546
--- /dev/null
+++ b/jank-build/README.md
@@ -0,0 +1,10 @@
+# jank-build
+[![Clojars Project](https://img.shields.io/clojars/v/org.jank-lang.commons/jank-build.svg)]
+Build script helper functions.
+
+## Usage
+Add this project to your Leiningen `:build-dependencies` vector:
+
+```clojure
+[org.jank-lang.commons/jank-build "0.1-SNAPSHOT"]
+```
diff --git a/jank-build/project.clj b/jank-build/project.clj
new file mode 100644
index 0000000..72422a4
--- /dev/null
+++ b/jank-build/project.clj
@@ -0,0 +1,9 @@
+(defproject org.jank-lang.commons/jank-build "0.1-SNAPSHOT"
+  :description "Build script helper functions"
+  :url "https://github.com/jank-lang/commons"
+  :license {:name "MPL 2.0"
+            :url  "https://www.mozilla.org/en-US/MPL/2.0/"}
+  :source-paths ["src" "test"]
+  :profiles {:dev {:dependencies [[org.clojure/clojure "1.12.6"]
+                                  [babashka/fs "0.5.34"]
+                                  [babashka/process "0.6.25"]]}})
diff --git a/jank-build/src/jank/build/cmake.clj b/jank-build/src/jank/build/cmake.clj
new file mode 100644
index 0000000..37245e2
--- /dev/null
+++ b/jank-build/src/jank/build/cmake.clj
@@ -0,0 +1,32 @@
+(ns jank.build.cmake
+  (:require [babashka.process :as proc]
+            [jank.build.util :as util]))
+
+(defn install-rpath []
+  (when (util/linux?) "$ORIGIN"))
+
+(defn default-defines [{:keys [out-dir optimization-level static?]
+                        :or   {optimization-level 0}}]
+  (let [rpath (install-rpath)]
+    (merge {"BUILD_SHARED_LIBS"        (if static? "OFF" "ON")
+            "CMAKE_BUILD_TYPE"         (if (pos? optimization-level) "Release" "Debug")
+            "CMAKE_INSTALL_PREFIX"     out-dir
+            ;; Make sure these paths are standardized, otherwise libs may
+            ;; sometimes go into lib64/ instea of lib/, etc.
+            "CMAKE_INSTALL_BINDIR"     "bin"
+            "CMAKE_INSTALL_LIBDIR"     "lib"
+            "CMAKE_INSTALL_INCLUDEDIR" "include"}
+           (when (and (not static?) rpath)
+             {"CMAKE_INSTALL_RPATH" rpath}))))
+
+(defn cmake
+  "Run the `cmake` tool in the src-dir, building to the intermediate build-dir,
+  and installing artifacts into the out-dir.
+
+  No jank-build directives are output, so make sure to specify the correct
+  link/include directories, link libraries, etc. yourself."
+  [{:keys [src-dir build-dir] :as input} & {:keys [defines target] :or {target "install"}}]
+  (let [d-flags (map (fn [[k v]] (str "-D" (name k) "=" v))
+                     (merge (default-defines input) defines))]
+    (proc/shell (concat ["cmake"] d-flags ["-B" build-dir src-dir]))
+    (proc/shell ["cmake" "--build" build-dir "--parallel" "--target" target])))
diff --git a/jank-build/src/jank/build/pkg_config.clj b/jank-build/src/jank/build/pkg_config.clj
new file mode 100644
index 0000000..3e33311
--- /dev/null
+++ b/jank-build/src/jank/build/pkg_config.clj
@@ -0,0 +1,66 @@
+(ns jank.build.pkg-config
+  (:require [clojure.string :as string]
+            [babashka.process :as proc]
+            [babashka.fs :as fs]
+            [jank.build.util :as util]))
+
+(defn parse-prefixed [prefix s]
+  (for [entry (string/split s #"\s+")
+        :when (string/starts-with? entry prefix)]
+    (subs entry (count prefix))))
+
+(defn has-static-lib? [lib link-dirs]
+  ; TODO: Windows?
+  (let [lib-name (str "lib" lib ".a")]
+    (some (fn [link-dir]
+            (let [link-dir+lib (fs/path link-dir lib-name)]
+              (when (fs/exists? link-dir+lib)
+                true)))
+          link-dirs)))
+
+(defn brew-pkg-config-path [build-input pkg]
+  (when (and (util/mac?) (fs/which "brew"))
+    (let [{:keys [exit out]} (proc/shell {:out :string
+                                          :err :string
+                                          :continue true
+                                          ; Disable brew's cache and use the already-authorized
+                                          ; working directory rather than /private/tmp.
+                                          :extra-env {"HOMEBREW_NO_BOOTSNAP" "1"
+                                                      "HOMEBREW_NO_AUTO_UPDATE" "1"
+                                                      "HOMEBREW_TEMP" (:out-dir build-input)}}
+                                         "brew" "--prefix")
+          prefix (string/trim out)]
+      (when (and (zero? exit) (not (string/blank? prefix)))
+        (str prefix "/opt/" pkg "/lib/pkgconfig")))))
+
+(defn pkg-config-path
+  "Rebuild the PKG_CONFIG_PATH string with additional paths prepended. nil
+  entries are ignored."
+  [& paths]
+  (let [sep      (System/getProperty "path.separator")
+        from-env (some-> (System/getenv "PKG_CONFIG_PATH")
+                         (not-empty)
+                         (string/split (re-pattern sep)))
+        fresh    (filter some? paths)]
+    (string/join sep (concat fresh from-env))))
+
+(defn pkg-config
+  "Call the `pkg-config` tool and parse link directories, include directories,
+  and link libraries.
+
+  jank-build directives will automatically be output for these values."
+  [build-input pc-name]
+  ;; TODO: parse preprocessor defines from cflags
+  (let [pc-cmd    (cond-> ["pkg-config" pc-name "--libs" "--cflags"]
+                    (:static? build-input) (conj "--static"))
+        brew-path (brew-pkg-config-path build-input pc-name)
+        pc-opts   {:extra-env {"PKG_CONFIG_PATH" (pkg-config-path brew-path)}
+                   :out       :string}
+        pc-output (->> pc-cmd (apply proc/shell pc-opts) :out)
+        link-dirs (parse-prefixed "-L" pc-output)]
+    (run! util/link-dir link-dirs)
+    (run! util/include-dir (parse-prefixed "-I" pc-output))
+    (run! #(if (and (:static? build-input) (has-static-lib? % link-dirs))
+             (util/link-static-library %)
+             (util/link-library %))
+          (parse-prefixed "-l" pc-output))))
diff --git a/jank-build/src/jank/build/util.clj b/jank-build/src/jank/build/util.clj
new file mode 100644
index 0000000..24ff88f
--- /dev/null
+++ b/jank-build/src/jank/build/util.clj
@@ -0,0 +1,54 @@
+(ns jank.build.util
+  (:require [clojure.string :as string]))
+
+;; OS identification functions are adapted from the Apache Commons
+;; Lang SystemUtils class.
+;;
+;; https://github.com/apache/commons-lang/blob/32dc4c501e3acba29d53a466eebd611bb2f093a5/src/main/java/org/apache/commons/lang3/SystemUtils.java
+
+(def os-name (System/getProperty "os.name"))
+
+(defn linux? []
+  (-> (string/lower-case os-name)
+      (string/starts-with? "linux")))
+
+(defn mac? []
+  (-> (string/lower-case os-name)
+      (string/starts-with? "mac")))
+
+(defn windows? []
+  (-> (string/lower-case os-name)
+      (string/starts-with? "windows")))
+
+;; Emit common "jank-build::"-prefixed items.
+
+(defn define
+  ([k] (println (str "jank-build::define=" k)))
+  ([k v] (println (str "jank-build::define=" k "=" v))))
+
+(defn include-dir
+  "Add a jank include-dir directive (a -I flag). If a relative path is given
+  then it is assumed to be relative to the build output directory."
+  [dir]
+  (println (str "jank-build::include-dir=" dir)))
+
+(defn link-dir
+  "Add a jank link-dir directive (a -L flag). If a relative path is given then
+  it is assumed to be relative to the build output directory."
+  [dir]
+  (println (str "jank-build::link-dir=" dir)))
+
+(defn link-library [lib]
+  (println (str "jank-build::link-library=" lib)))
+
+(defn link-static-library [lib]
+  (println (str "jank-build::link-static-library=" lib)))
+
+(defn link-framework [framework]
+  (println (str "jank-build::link-framework=" framework)))
+
+(defn rerun-if-changed [path]
+  (println (str "jank-build::rerun-if-changed=" path)))
+
+(defn rerun-if-env-changed [k]
+  (println (str "jank-build::rerun-if-env-changed=" k)))
diff --git a/jank-build/test-data/cmake-project/CMakeLists.txt b/jank-build/test-data/cmake-project/CMakeLists.txt
new file mode 100644
index 0000000..9dae37b
--- /dev/null
+++ b/jank-build/test-data/cmake-project/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.12)
+project(cmake_project VERSION 1.0 LANGUAGES CXX)
+add_library(foo foo.cpp)
diff --git a/jank-build/test-data/cmake-project/foo.cpp b/jank-build/test-data/cmake-project/foo.cpp
new file mode 100644
index 0000000..b85b60d
--- /dev/null
+++ b/jank-build/test-data/cmake-project/foo.cpp
@@ -0,0 +1,4 @@
+int foo()
+{
+  return 42;
+}
diff --git a/jank-build/test/jank/build/cmake_test.clj b/jank-build/test/jank/build/cmake_test.clj
new file mode 100644
index 0000000..dec4153
--- /dev/null
+++ b/jank-build/test/jank/build/cmake_test.clj
@@ -0,0 +1,15 @@
+(ns jank.build.cmake-test
+  (:require [clojure.test :refer [deftest is]]
+            [clojure.string :as string]
+            [babashka.fs :as fs]
+            [jank.build.cmake :as cm]))
+
+(def test-project-dir (fs/path "test-data/cmake-project"))
+
+(deftest build-example-project-test
+  ;; should not throw
+  (cm/cmake {:src-dir   test-project-dir
+             :build-dir (fs/create-temp-dir {:prefix "jank-build-cmake-test"})
+             :out-dir   (fs/create-temp-dir {:prefix "jank-build-cmake-test"})}
+            {:defines {:SOME_DEFINE true}
+             :target  "all"}))
diff --git a/jank-build/test/jank/build/pkg_config_test.clj b/jank-build/test/jank/build/pkg_config_test.clj
new file mode 100644
index 0000000..d63c509
--- /dev/null
+++ b/jank-build/test/jank/build/pkg_config_test.clj
@@ -0,0 +1,11 @@
+(ns jank.build.pkg-config-test
+  (:require [clojure.test :refer [deftest is]]
+            [clojure.string :as string]
+            [jank.build.pkg-config :as pc]))
+
+;; zlib should be on all jank-enabled systems.
+(deftest find-zlib-test
+  (let [out (with-out-str *out* (pc/pkg-config {} "zlib"))]
+    (is (string/includes? out "jank-build::link-dir="))
+    (is (string/includes? out "jank-build::include-dir="))
+    (is (string/includes? out "jank-build::link-library=z"))))
diff --git a/jank-build/test/jank/build/util_test.clj b/jank-build/test/jank/build/util_test.clj
new file mode 100644
index 0000000..c691e8b
--- /dev/null
+++ b/jank-build/test/jank/build/util_test.clj
@@ -0,0 +1,35 @@
+(ns jank.build.util-test
+  (:require [clojure.test :refer [deftest is]]
+            [jank.build.util :as util]))
+
+(deftest os-detection-test
+  (with-redefs [util/os-name "Linux"]
+    (is (util/linux?))
+    (is (not (util/mac?)))
+    (is (not (util/windows?))))
+  (with-redefs [util/os-name "Mac OS X"]
+    (is (util/mac?))
+    (is (not (util/linux?)))
+    (is (not (util/windows?))))
+  (with-redefs [util/os-name "Windows XP"]
+    (is (util/windows?))
+    (is (not (util/linux?)))
+    (is (not (util/mac?)))))
+
+(deftest build-directives-test
+  (is (= (with-out-str (util/define "KEY"))
+         "jank-build::define=KEY\n"))
+  (is (= (with-out-str (util/define "KEY" "VAL"))
+         "jank-build::define=KEY=VAL\n"))
+  (is (= (with-out-str (util/include-dir "/usr/include"))
+         "jank-build::include-dir=/usr/include\n"))
+  (is (= (with-out-str (util/link-dir "/usr/lib64"))
+         "jank-build::link-dir=/usr/lib64\n"))
+  (is (= (with-out-str (util/link-library "m"))
+         "jank-build::link-library=m\n"))
+  (is (= (with-out-str (util/link-framework "Cocoa"))
+         "jank-build::link-framework=Cocoa\n"))
+  (is (= (with-out-str (util/rerun-if-changed "/home"))
+         "jank-build::rerun-if-changed=/home\n"))
+  (is (= (with-out-str (util/rerun-if-env-changed "PATH"))
+         "jank-build::rerun-if-env-changed=PATH\n")))