diff --git a/libexec/rbenv-commands b/libexec/rbenv-commands
index 297f8d99..67bc7fb9 100755
--- a/libexec/rbenv-commands
+++ b/libexec/rbenv-commands
@@ -1,4 +1,6 @@
 #!/usr/bin/env bash
+# Usage: rbenv commands [ --sh | --no-sh ]
+# Summary: List all rbenv commands
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
diff --git a/libexec/rbenv-help b/libexec/rbenv-help
index e1cbaf57..7a710512 100755
--- a/libexec/rbenv-help
+++ b/libexec/rbenv-help
@@ -2,6 +2,51 @@
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
+# content from single commented line marked with a word such as "Usage" or "Summary"
+extract_line() {
+  grep "^# ${1}:" "$2" | head -1 | cut -d ' ' -f3-
+}
+
+# content of multiple consecutive commented lines starting with a word such as "Help"
+extract_section() {
+  sed -En "/^# ${1}: /,/^[^#]/s/^# ?//p" "$2" | sed "1s/${1}: //"
+}
+
+# print aligned command names with help summary
+print_summary() {
+  if [ ! -h "$1" ]; then
+    local summary=$(extract_line Summary "$1")
+    if [ -n "$summary" ]; then
+      local name=$(basename "$1")
+      echo "${name#rbenv-}" | awk '{ printf "   %-14s   ", $1 }'
+      echo -n $summary
+      echo
+    else
+      return 1
+    fi
+  fi
+}
+
+print_help() {
+  local usage="$(extract_line Usage "$1")"
+  local halp="$(extract_section Help "$1")"
+  [ -z "$halp" ] && halp="$(extract_line Summary "$1")"
+
+  if [ -n "$usage" ]; then
+    echo usage: $usage
+    [ -n "$halp" ] && echo && echo "$halp"
+  else
+    echo "Sorry, this command isn't documented yet." >&2
+    return 1
+  fi
+}
+
+print_summaries() {
+  for command in $1; do
+    print_summary "$(command -v rbenv-"$command")"
+  done
+}
+
 print_set_version() {
   echo "<version> should be a string matching a Ruby version known by rbenv."
 
@@ -21,25 +66,11 @@ case "$1" in
 "") echo "usage: rbenv <command> [<args>]
 
 Some useful rbenv commands are:
-   commands      List all rbenv commands
-   rehash        Rehash rbenv shims (run this after installing binaries)
-   global        Set or show the global Ruby version
-   local         Set or show the local directory-specific Ruby version
-   shell         Set or show the shell-specific Ruby version
-   version       Show the current Ruby version
-   versions      List all Ruby versions known by rbenv
-   which         Show the full path for the given Ruby command
-   whence        List all Ruby versions with the given command
+$(print_summaries "commands rehash global local shell version versions which whence")
 
 See 'rbenv help <command>' for information on a specific command.
 For full documentation, see: https://github.com/sstephenson/rbenv#readme"
 ;;
-commands) echo "usage: rbenv commands
-       rbenv commands --sh
-       rbenv commands --no-sh
-
-List all rbenv commands."
-;;
 global) echo "usage: rbenv global <version>
 
 Sets the global Ruby version. You can override the global version at
@@ -71,29 +102,12 @@ project-specific versions and the global version.
 
 $(print_set_version)"
 ;;
-versions) echo "usage: rbenv versions
-       rbenv versions --bare
-
-Lists all Ruby versions known by rbenv."
-;;
-which) echo "usage: rbenv which <command>
-
-Displays the full path to the binary that rbenv will execute when you
-run the given command."
-;;
-whence) echo "usage: rbenv whence <command>
-
-Lists all Ruby versions with the given command installed."
-;;
 *)
   command_path="$(command -v "rbenv-$1" || true)"
   if [ -n "$command_path" ]; then
-    echo "Sorry, the \`$1' command isn't documented yet."
-    echo
-    echo "You can view the command's source here:"
-    echo "$command_path"
-    echo
+    print_help "$command_path"
   else
-    echo "rbenv: no such command \`$1'"
+    echo "rbenv: no such command \`$1'" >&2
+    exit 1
   fi
 esac
diff --git a/libexec/rbenv-rehash b/libexec/rbenv-rehash
index eebc4d3c..13bd7938 100755
--- a/libexec/rbenv-rehash
+++ b/libexec/rbenv-rehash
@@ -1,4 +1,6 @@
 #!/usr/bin/env bash
+# Usage: rbenv rehash
+# Summary: Rehash rbenv shims (run this after installing binaries)
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
diff --git a/libexec/rbenv-versions b/libexec/rbenv-versions
index 346800a3..46b8a021 100755
--- a/libexec/rbenv-versions
+++ b/libexec/rbenv-versions
@@ -1,4 +1,6 @@
 #!/usr/bin/env bash
+# Usage: rbenv versions [--bare]
+# Summary: List all Ruby versions known by rbenv
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
diff --git a/libexec/rbenv-whence b/libexec/rbenv-whence
index 8a926877..5e49d527 100755
--- a/libexec/rbenv-whence
+++ b/libexec/rbenv-whence
@@ -1,4 +1,6 @@
 #!/usr/bin/env bash
+# Usage: rbenv whence [--path] COMMAND
+# Summary: List all Ruby versions with the given command installed
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
@@ -27,7 +29,7 @@ whence() {
 
 RBENV_COMMAND="$1"
 if [ -z "$RBENV_COMMAND" ]; then
-  echo "usage: rbenv whence [--path] COMMAND" >&2
+  rbenv-help whence | head -1 >&2
   exit 1
 fi
 
diff --git a/libexec/rbenv-which b/libexec/rbenv-which
index 204988b2..3cdddd01 100755
--- a/libexec/rbenv-which
+++ b/libexec/rbenv-which
@@ -1,4 +1,8 @@
 #!/usr/bin/env bash
+# Usage: rbenv which COMMAND
+# Summary: Display full path to a binary
+# Help: Displays the full path to the binary that rbenv will execute when you
+# run the given command.
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
@@ -44,7 +48,7 @@ RBENV_VERSION="$(rbenv-version-name)"
 RBENV_COMMAND="$1"
 
 if [ -z "$RBENV_COMMAND" ]; then
-  echo "usage: rbenv which COMMAND" >&2
+  rbenv-help which | head -1 >&2
   exit 1
 fi