diff --git a/changelog.txt b/changelog.txt
index ba1435d045..6bcec1b704 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -27,6 +27,7 @@ Template for new versions:
 # Future
 
 ## New Tools
+- `sync-windmills`: synchronize or randomize movement of active windmills
 
 ## New Features
 
diff --git a/docs/sync-windmills.rst b/docs/sync-windmills.rst
new file mode 100644
index 0000000000..21bf44e156
--- /dev/null
+++ b/docs/sync-windmills.rst
@@ -0,0 +1,41 @@
+sync-windmills
+==============
+
+.. dfhack-tool::
+    :summary: Synchronize or randomize windmill movement.
+    :tags: fort buildings
+
+Windmills cycle between two graphical states to simulate movement. This is the
+polarity of the appearance. Each windmill also has a timer that controls when
+the windmill switches polarity. Each windmill's timer starts from zero at the
+instant that it is built, so two different windmills will rarely have exactly
+the same state. This tool can adjust the alignment of polarity and timers
+across your active windmills to your preference.
+
+Note that this tool will not affect windmills that have just been activated and
+are still rotating to adjust to the regional wind direction.
+
+Usage
+-----
+
+::
+
+    sync-windmills [<options>]
+
+Examples
+--------
+
+``sync-windmills``
+    Synchronize movement of all active windmills.
+``sync-windmills -r``
+    Randomize the movement of all active windmills.
+
+Options
+-------
+
+``-q``, ``--quiet``
+    Suppress non-error console output.
+``-r``, ``--randomize``
+    Randomize the polarity and timer value for all windmills.
+``-t``, ``--timing-only``
+    Randomize windmill polarity, but synchronize windmill timers.
diff --git a/sync-windmills.lua b/sync-windmills.lua
new file mode 100644
index 0000000000..cc25703395
--- /dev/null
+++ b/sync-windmills.lua
@@ -0,0 +1,37 @@
+local argparse = require('argparse')
+
+local function process_windmills(rotate_fn, timer_fn)
+    for _, bld in ipairs(df.global.world.buildings.other.WINDMILL) do
+        if bld.is_working ~= 0 then
+            bld.visual_rotated = rotate_fn()
+            bld.rotate_timer = timer_fn()
+        end
+    end
+end
+
+local opts = {}
+argparse.processArgsGetopt({...}, {
+    { 'h', 'help', handler = function() opts.help = true end },
+    { 'q', 'quiet', handler = function() opts.quiet = true end },
+    { 'r', 'randomize', handler = function() opts.randomize = true end },
+    { 't', 'timing-only', handler = function() opts.timing = true end },
+})
+
+if opts.help then
+    print(dfhack.script_help())
+    return
+end
+
+process_windmills(
+    (opts.randomize or opts.timing) and
+        function() return math.random(1, 2) == 1 end or
+        function() return false end,
+    opts.randomize and not opts.timing and
+        function() return math.random(0, 74) end or
+        function() return 0 end)
+
+if not opts.quiet then
+    print(('%d windmills %s'):format(
+        #df.global.world.buildings.other.WINDMILL,
+        opts.randomize and 'randomized' or 'synchronized'))
+end