diff --git a/completions/bash/brew b/completions/bash/brew
index 07bb265f60..b742579eec 100644
--- a/completions/bash/brew
+++ b/completions/bash/brew
@@ -911,6 +911,23 @@ _brew_formula() {
   __brew_complete_formulae
 }
 
+_brew_generate_man_completions() {
+  local cur="${COMP_WORDS[COMP_CWORD]}"
+  case "${cur}" in
+    -*)
+      __brewcomp "
+      --debug
+      --fail-if-not-changed
+      --help
+      --quiet
+      --verbose
+      "
+      return
+      ;;
+    *)
+  esac
+}
+
 _brew_gist_logs() {
   local cur="${COMP_WORDS[COMP_CWORD]}"
   case "${cur}" in
@@ -2439,6 +2456,7 @@ _brew() {
     extract) _brew_extract ;;
     fetch) _brew_fetch ;;
     formula) _brew_formula ;;
+    generate-man-completions) _brew_generate_man_completions ;;
     gist-logs) _brew_gist_logs ;;
     home) _brew_home ;;
     homepage) _brew_homepage ;;
diff --git a/completions/fish/brew.fish b/completions/fish/brew.fish
index 383e6e61b0..0c5dd4f485 100644
--- a/completions/fish/brew.fish
+++ b/completions/fish/brew.fish
@@ -671,6 +671,14 @@ __fish_brew_complete_arg 'formula' -l verbose -d 'Make some output more verbose'
 __fish_brew_complete_arg 'formula' -a '(__fish_brew_suggest_formulae_all)'
 
 
+__fish_brew_complete_cmd 'generate-man-completions' 'Generate Homebrew\'s manpages'
+__fish_brew_complete_arg 'generate-man-completions' -l debug -d 'Display any debugging information'
+__fish_brew_complete_arg 'generate-man-completions' -l fail-if-not-changed -d 'Return a failing status code if no changes are detected in the manpage outputs. This can be used to notify CI when the manpages are out of date. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date)'
+__fish_brew_complete_arg 'generate-man-completions' -l help -d 'Show this message'
+__fish_brew_complete_arg 'generate-man-completions' -l quiet -d 'Make some output more quiet'
+__fish_brew_complete_arg 'generate-man-completions' -l verbose -d 'Make some output more verbose'
+
+
 __fish_brew_complete_cmd 'gist-logs' 'Upload logs for a failed build of formula to a new Gist'
 __fish_brew_complete_arg 'gist-logs' -l debug -d 'Display any debugging information'
 __fish_brew_complete_arg 'gist-logs' -l help -d 'Show this message'
diff --git a/completions/internal_commands_list.txt b/completions/internal_commands_list.txt
index 0b5931a16e..b23578fc26 100644
--- a/completions/internal_commands_list.txt
+++ b/completions/internal_commands_list.txt
@@ -39,6 +39,7 @@ extract
 fetch
 formula
 formulae
+generate-man-completions
 gist-logs
 help
 home
diff --git a/completions/zsh/_brew b/completions/zsh/_brew
index c0f710baeb..4c45810c91 100644
--- a/completions/zsh/_brew
+++ b/completions/zsh/_brew
@@ -162,6 +162,7 @@ __brew_internal_commands() {
     'fetch:Download a bottle (if available) or source packages for formulae and binaries for casks'
     'formula:Display the path where formula is located'
     'formulae:List all locally installable formulae including short names'
+    'generate-man-completions:Generate Homebrew'\''s manpages'
     'gist-logs:Upload logs for a failed build of formula to a new Gist'
     'home:Open a formula or cask'\''s homepage in a browser, or open Homebrew'\''s own homepage if no argument is provided'
     'info:Display brief statistics for your Homebrew installation'
@@ -831,6 +832,16 @@ _brew_formula() {
     '*::formula:__brew_formulae'
 }
 
+# brew generate-man-completions
+_brew_generate_man_completions() {
+  _arguments \
+    '--debug[Display any debugging information]' \
+    '--fail-if-not-changed[Return a failing status code if no changes are detected in the manpage outputs. This can be used to notify CI when the manpages are out of date. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date)]' \
+    '--help[Show this message]' \
+    '--quiet[Make some output more quiet]' \
+    '--verbose[Make some output more verbose]'
+}
+
 # brew gist-logs
 _brew_gist_logs() {
   _arguments \
diff --git a/docs/Manpage.md b/docs/Manpage.md
index 3c42e02c71..72c9c675d5 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -1059,6 +1059,13 @@ a formula from a tap that is not `homebrew/core` use its fully-qualified form of
 
 Display the path where *`formula`* is located.
 
+### `generate-man-completions` [*`--fail-if-not-changed`*]
+
+Generate Homebrew's manpages.
+
+* `--fail-if-not-changed`:
+  Return a failing status code if no changes are detected in the manpage outputs. This can be used to notify CI when the manpages are out of date. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date).
+
 ### `install-bundler-gems`
 
 Install Homebrew's Bundler gems.
@@ -1111,13 +1118,6 @@ casks to check is taken from `HOMEBREW_LIVECHECK_WATCHLIST` or
 * `--cask`:
   Only check casks.
 
-### `man` [*`--fail-if-not-changed`*]
-
-Generate Homebrew's manpages.
-
-* `--fail-if-not-changed`:
-  Return a failing status code if no changes are detected in the manpage outputs. This can be used to notify CI when the manpages are out of date. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date).
-
 ### `pr-automerge` [*`options`*]
 
 Find pull requests that can be automatically merged using `brew pr-publish`.
@@ -1548,14 +1548,16 @@ to send a notification when the autoupdate process has finished successfully.
 <br>Prints the current status of this tool.
 
 `brew autoupdate version`
-<br>Output this tool's current version.
+<br>Output this tool's current version, and a short changelog.
 
 * `--upgrade`:
   Automatically upgrade your installed formulae. If the Caskroom exists locally Casks will be upgraded as well. Must be passed with `start`.
 * `--cleanup`:
   Automatically clean brew's cache and logs. Must be passed with `start`.
 * `--enable-notification`:
-  Send a notification when the autoupdate process has finished successfully, if `terminal-notifier` is installed & found. Note that currently a new experimental notifier runs automatically on macOS Big Sur, without requiring any external dependencies. Must be passed with `start`.
+  Send a notification when the autoupdate process has finished successfully, if `terminal-notifier` is installed & found. Note that currently a new experimental notifier runs automatically on macOS Catalina and newer, without requiring any external dependencies. Must be passed with `start`.
+* `--immediate`:
+  Starts the autoupdate command immediately, instead of waiting for one interval (24 hours by default) to pass first. Must be passed with `start`.
 
 ### `bundle` [*`subcommand`*]
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 8766af210c..0ab308e46d 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1480,6 +1480,13 @@ Overwrite the destination formula if it already exists\.
 .SS "\fBformula\fR \fIformula\fR [\.\.\.]"
 Display the path where \fIformula\fR is located\.
 .
+.SS "\fBgenerate\-man\-completions\fR [\fI\-\-fail\-if\-not\-changed\fR]"
+Generate Homebrew\'s manpages\.
+.
+.TP
+\fB\-\-fail\-if\-not\-changed\fR
+Return a failing status code if no changes are detected in the manpage outputs\. This can be used to notify CI when the manpages are out of date\. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date)\.
+.
 .SS "\fBinstall\-bundler\-gems\fR"
 Install Homebrew\'s Bundler gems\.
 .
@@ -1551,13 +1558,6 @@ Only check formulae\.
 \fB\-\-cask\fR
 Only check casks\.
 .
-.SS "\fBman\fR [\fI\-\-fail\-if\-not\-changed\fR]"
-Generate Homebrew\'s manpages\.
-.
-.TP
-\fB\-\-fail\-if\-not\-changed\fR
-Return a failing status code if no changes are detected in the manpage outputs\. This can be used to notify CI when the manpages are out of date\. Additionally, the date used in new manpages will match those in the existing manpages (to allow comparison without factoring in the date)\.
-.
 .SS "\fBpr\-automerge\fR [\fIoptions\fR]"
 Find pull requests that can be automatically merged using \fBbrew pr\-publish\fR\.
 .
@@ -2150,7 +2150,7 @@ This script will run \fBbrew update\fR in the background once every 24 hours (by
 .
 .P
 \fBbrew autoupdate version\fR
-    Output this tool\'s current version\.
+    Output this tool\'s current version, and a short changelog\.
 .
 .TP
 \fB\-\-upgrade\fR
@@ -2162,7 +2162,11 @@ Automatically clean brew\'s cache and logs\. Must be passed with \fBstart\fR\.
 .
 .TP
 \fB\-\-enable\-notification\fR
-Send a notification when the autoupdate process has finished successfully, if \fBterminal\-notifier\fR is installed & found\. Note that currently a new experimental notifier runs automatically on macOS Big Sur, without requiring any external dependencies\. Must be passed with \fBstart\fR\.
+Send a notification when the autoupdate process has finished successfully, if \fBterminal\-notifier\fR is installed & found\. Note that currently a new experimental notifier runs automatically on macOS Catalina and newer, without requiring any external dependencies\. Must be passed with \fBstart\fR\.
+.
+.TP
+\fB\-\-immediate\fR
+Starts the autoupdate command immediately, instead of waiting for one interval (24 hours by default) to pass first\. Must be passed with \fBstart\fR\.
 .
 .SS "\fBbundle\fR [\fIsubcommand\fR]"
 Bundler for non\-Ruby dependencies from Homebrew, Homebrew Cask, Mac App Store and Whalebrew\.