diff --git a/share/completions/fish.fish b/share/completions/fish.fish
index 2038f0c78..ab3bfcdde 100644
--- a/share/completions/fish.fish
+++ b/share/completions/fish.fish
@@ -1,9 +1,24 @@
-complete -c fish -s c -l "command" -d "Run fish with this command"
+complete -c fish -s c -l command -d "Run specified command instead of interactive session" -x -a "(__fish_complete_command)"
+complete -c fish -s C -l init-command -d "Run specified command before session" -x -a "(__fish_complete_command)"
 complete -c fish -s h -l help -d "Display help and exit"
 complete -c fish -s v -l version -d "Display version and exit"
 complete -c fish -s n -l no-execute -d "Only parse input, do not execute"
 complete -c fish -s i -l interactive -d "Run in interactive mode"
-complete -c fish -s l -l login -d "Run in login mode"
-complete -c fish -s p -l profile -d "Output profiling information to specified file" -f
-complete -c fish -s d -l debug -d "Run with the specified verbosity level"
-complete -c fish -s P -l private -d "Run fish in private mode"
+complete -c fish -s l -l login -d "Run as a login shell"
+complete -c fish -s p -l profile -d "Output profiling information to specified file" -r
+complete -c fish -s d -l debug-level -d "Specify verbosity level" -x -a "0\t'Warnings silenced'
+1\t'Default'
+2\t'Basic debug output'
+3\t'More debug output'
+4\t'Much more debug output'
+5\t'Too much debug output'"
+complete -c fish -s D -l debug-stack-frames -d "Show specified # of frames with debug output" -x -a "(seq 128)\t\n"
+complete -c fish -s P -l private -d "Do not persist history"
+
+function __fish_complete_features
+    set -l arg_comma (commandline -tc | string replace -rf '(.*,)[^,]*' '$1' | string replace -r -- '--.*=' '')
+    set -l features (status features | string replace -rf '^([\w-]+).*\t(.*)$' '$1\t$2')
+    printf "%s\n" "$arg_comma"$features #TODO: remove existing args
+end
+complete -c fish -s f -l features -d "Run with comma-separated feature flags enabled" -a "(__fish_complete_features)" -x
+complete -c fish -x -a "(__fish_complete_suffix .fish)"
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