diff --git a/.watchmanconfig b/.watchmanconfig
index e69de29..0967ef4 100644
--- a/.watchmanconfig
+++ b/.watchmanconfig
@@ -0,0 +1 @@
+{}
diff --git a/doc/command-t.txt b/doc/command-t.txt
index d8dd1f4..f77047b 100644
--- a/doc/command-t.txt
+++ b/doc/command-t.txt
@@ -1413,32 +1413,32 @@ AUTHORS                                         *command-t-authors*
 Command-T is written and maintained by Greg Hurrell <greg@hurrell.net>.
 Other contributors that have submitted patches include, in alphabetical order:
 
-  Abhinav Gupta                   Nate Kane
-  Adrian Keet                     Nicholas T.
-  Aleksandrs Ļedovskis            Nicolas Alpi
-  Alexey Terekhov                 Nikolai Aleksandrovich Pavlov
-  Andrius Grabauskas              Nilo César Teixeira
-  Andy Waite                      Noon Silk
-  Anthony Panozzo                 Ole Petter Bang
-  Artem Nezvigin                  Patrick Hayes
-  Ben Boeckel                     Paul Jolly
-  Brendan Mulholland              Pavel Sergeev
-  Daniel Burgess                  Rainux Luo
-  Daniel Hahler                   Richard Feldman
-  David Emett                     Roland Puntaier
-  David Szotten                   Ross Lagerwall
-  Douglas Drumond                 Sam Morris
-  Emily Strickland                Scott Bronson
-  Felix Tjandrawibawa             Seth Fowler
-  Gary Bernhardt                  Sherzod Gapirov
-  Henric Trotzig                  Shlomi Fish
-  Ivan Ukhov                      Stefan Schmidt
-  Jakob Pfender                   Stephen Gelman
-  Jeff Kreeftmeijer               Steve Herrell
-  Jerome Castaneda                Steven Moazami
-  Joe Lencioni                    Steven Stallion
-  KJ Tsanaktsidis                 Sung Pae
-  Kevin Webster                   Thomas Pelletier
+  Abhinav Gupta                   Nicholas T.
+  Adrian Keet                     Nicolas Alpi
+  Aleksandrs Ļedovskis            Nikolai Aleksandrovich Pavlov
+  Alexey Terekhov                 Nilo César Teixeira
+  Andrius Grabauskas              Noon Silk
+  Andy Waite                      Ole Petter Bang
+  Anthony Panozzo                 Patrick Hayes
+  Artem Nezvigin                  Paul Jolly
+  Ben Boeckel                     Pavel Sergeev
+  Brendan Mulholland              Rainux Luo
+  Daniel Burgess                  Richard Feldman
+  Daniel Hahler                   Roland Puntaier
+  David Emett                     Ross Lagerwall
+  David Szotten                   Sam Morris
+  Douglas Drumond                 Scott Bronson
+  Emily Strickland                Seth Fowler
+  Felix Tjandrawibawa             Sherzod Gapirov
+  Gary Bernhardt                  Shlomi Fish
+  Henric Trotzig                  Stefan Schmidt
+  Ivan Ukhov                      Stephen Gelman
+  Jakob Pfender                   Steve Herrell
+  Jeff Kreeftmeijer               Steven Moazami
+  Jerome Castaneda                Steven Stallion
+  Joe Lencioni                    Sung Pae
+  KJ Tsanaktsidis                 Thomas Pelletier
+  Kevin Webster                   Todd Derr
   Kien Nguyen Duc                 Ton van den Heuvel
   Lucas de Vries                  Victor Hugo Borja
   Marcus Brito                    Vlad Seghete
@@ -1447,6 +1447,7 @@ Other contributors that have submitted patches include, in alphabetical order:
   Max Timkovich                   Yan Pritzker
   Mike Lundy                      Zak Johnson
   Nadav Samet                     xiaodezhang
+  Nate Kane
 
 This list produced with:
 
@@ -1572,6 +1573,11 @@ POSSIBILITY OF SUCH DAMAGE.
 
 HISTORY                                         *command-t-history*
 
+main (not yet released) ~
+
+- Teach watchman scanner to favor `watch-project` over `watch` when
+  available (#390, patch from Todd Derr).
+
 5.0.4 (28 May 2022) ~
 
 - Support opening files which contain newlines (#365).
diff --git a/ruby/command-t/lib/command-t/scanner/file_scanner/watchman_file_scanner.rb b/ruby/command-t/lib/command-t/scanner/file_scanner/watchman_file_scanner.rb
index 60f412a..5616d8f 100644
--- a/ruby/command-t/lib/command-t/scanner/file_scanner/watchman_file_scanner.rb
+++ b/ruby/command-t/lib/command-t/scanner/file_scanner/watchman_file_scanner.rb
@@ -25,20 +25,29 @@ def paths!
 
           UNIXSocket.open(sockname) do |socket|
             root = Pathname.new(@path).realpath.to_s
-            roots = Watchman::Utils.query(['watch-list'], socket)['roots']
-            if !roots.include?(root)
-              # this path isn't being watched yet; try to set up watch
-              result = Watchman::Utils.query(['watch', root], socket)
+            # Use `watch-project` for efficiency if available.
+            if use_watch_project?
+                result = Watchman::Utils.query(['watch-project', root], socket)
+                root = extract_value(result, 'watch')
+                relative_root = extract_value(result, 'relative_path') if result.has_key?('relative_path')
+            else
+              roots = Watchman::Utils.query(['watch-list'], socket)['roots']
+              if !roots.include?(root)
+                # This path isn't being watched yet; try to set up watch.
+                result = Watchman::Utils.query(['watch', root], socket)
 
-              # root_restrict_files setting may prevent Watchman from working
-              # or enforce_root_files/root_files (>= version 3.1)
-              extract_value(result)
+                # `root_restrict_files` setting may prevent Watchman from
+                # working or enforce_root_files/root_files (>= version 3.1).
+                extract_value(result)
+              end
             end
 
-            query = ['query', root, {
+            query_params = {
               'expression' => ['type', 'f'],
               'fields'     => ['name'],
-            }]
+            }
+            query_params['relative_root'] = relative_root if relative_root
+            query = ['query', root, query_params]
             paths = Watchman::Utils.query(query, socket)
 
             # could return error if watch is removed
@@ -68,6 +77,15 @@ def get_raw_sockname
           end
           raw_sockname
         end
+
+        # `watch_project` is available in 3.1+ but it's awkward to use without
+        # `relative_root` (3.3+), so use the latter as our minimum version.
+        def use_watch_project?
+          return @use_watch_project if defined?(@use_watch_project)
+          version = %x{watchman --version 2>/dev/null}
+          major, minor = version.split('.')[0..1] if !$?.exitstatus.nil? && $?.exitstatus.zero? && version
+          @use_watch_project = major.to_i > 3 || (major.to_i == 3 && minor.to_i >= 3)
+        end
       end
     end
   end