diff --git a/completions/rbenv.bash b/completions/rbenv.bash
new file mode 100644
index 00000000..0e8a383d
--- /dev/null
+++ b/completions/rbenv.bash
@@ -0,0 +1,29 @@
+_rbenv_commands() {
+  COMPREPLY=()
+  local cur="${COMP_WORDS[COMP_CWORD]}"
+  COMPREPLY=( $( compgen -W "$(rbenv commands)" -- $cur ) )
+}
+
+_rbenv_versions() {
+  COMPREPLY=()
+  local cur="${COMP_WORDS[COMP_CWORD]}"
+  local versions="$(echo system; rbenv versions --bare)"
+  COMPREPLY=( $( compgen -W "$versions" -- $cur ) )
+}
+
+_rbenv() {
+  COMPREPLY=()
+  local cur="${COMP_WORDS[COMP_CWORD]}"
+  local prev="${COMP_WORDS[COMP_CWORD-1]}"
+
+  case "$prev" in
+  set-* | prefix )
+    _rbenv_versions
+    ;;
+  * )
+    _rbenv_commands
+    ;;
+  esac
+}
+
+complete -F _rbenv rbenv
diff --git a/libexec/rbenv-commands b/libexec/rbenv-commands
new file mode 100755
index 00000000..49ba268b
--- /dev/null
+++ b/libexec/rbenv-commands
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash -e
+
+shopt -s nullglob
+
+{ for path in ${PATH//:/$'\n'}; do
+    for command in "${path}/rbenv-"*; do
+      echo "${command##*rbenv-}"
+    done
+  done
+} | sort | uniq
+
diff --git a/libexec/rbenv-prefix b/libexec/rbenv-prefix
index f2823b31..9d17ee42 100755
--- a/libexec/rbenv-prefix
+++ b/libexec/rbenv-prefix
@@ -6,6 +6,12 @@ elif [ -z "$RBENV_VERSION" ]; then
   RBENV_VERSION="$(rbenv-version)"
 fi
 
+if [ "$RBENV_VERSION" = "system" ]; then
+  RUBY_PATH="$(rbenv-which ruby)"
+  echo "${RUBY_PATH%/*}"
+  exit
+fi
+
 RBENV_PREFIX_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}"
 if [ ! -d "$RBENV_PREFIX_PATH" ]; then
   echo "rbenv: version \`${RBENV_VERSION}' not installed" >&2
diff --git a/libexec/rbenv-version b/libexec/rbenv-version
index 01c1afdf..2c9cae13 100755
--- a/libexec/rbenv-version
+++ b/libexec/rbenv-version
@@ -36,6 +36,11 @@ if [ -z "$RBENV_VERSION" ]; then
   fi
 fi
 
+if [ "$RBENV_VERSION" = "system" ]; then
+  echo "$RBENV_VERSION"
+  exit
+fi
+
 RBENV_VERSION_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}"
 
 if [ -d "$RBENV_VERSION_PATH" ]; then
diff --git a/libexec/rbenv-which b/libexec/rbenv-which
index 74572f47..f38bba61 100755
--- a/libexec/rbenv-which
+++ b/libexec/rbenv-which
@@ -1,8 +1,35 @@
 #!/usr/bin/env bash -e
 
+expand_path() {
+  local cwd="$(pwd)"
+  cd "$1"
+  pwd
+  cd "$cwd"
+}
+
+remove_from_path() {
+  local path_to_remove="$(expand_path "$1")"
+  local result=""
+
+  for path in ${PATH//:/$'\n'}; do
+    path="$(expand_path "$path" || true)"
+    if [ "$path" != "$path_to_remove" ]; then
+      result="${result}${path}:"
+    fi
+  done
+
+  echo "${result%:}"
+}
+
 RBENV_VERSION="$(rbenv-version)"
 RBENV_COMMAND="$1"
-RBENV_COMMAND_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}/bin/${RBENV_COMMAND}"
+
+if [ "$RBENV_VERSION" = "system" ]; then
+  PATH="$(remove_from_path "${HOME}/.rbenv/shims")"
+  RBENV_COMMAND_PATH="$(command -v "$RBENV_COMMAND")"
+else
+  RBENV_COMMAND_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}/bin/${RBENV_COMMAND}"
+fi
 
 shopt -s nullglob
 RBENV_WHICH_PLUGINS=(/etc/rbenv.d/which/*.bash ${HOME}/.rbenv/rbenv.d/which/*.bash)