diff --git a/cpdf.ml b/cpdf.ml
index 9b68401..62db932 100644
--- a/cpdf.ml
+++ b/cpdf.ml
@@ -2063,10 +2063,26 @@ let rec insert_after_many_changes isbefore padsize offset range = function
 let print_changes =
   List.iter (fun (f, t) -> Printf.printf "%i --> %i\n" f t)
 
-let pad_with_pdf range pdf isbefore padfile =
-  (* 1. Split the input pdf around the range, taking account of isbefore *)
-  (* 2. Build a merge after "a p b p c p" or before "p a p b p c" *)
-  pdf
+let pad_with_pdf (range : int list) (pdf : Pdf.t) (isbefore : bool) (padfile : Pdf.t) =
+  let range = List.sort compare (setify range) in
+  let merged =
+    Pdfmerge.merge_pdfs
+      false false ["a"; "b"] [pdf; padfile] [ilist 1 (Pdfpage.endpage pdf); ilist 1 (Pdfpage.endpage padfile)]
+  in
+  let original_pages, padpages =
+    cleave (Pdfpage.pages_of_pagetree merged) (Pdfpage.endpage pdf) 
+  in
+    let newpages =
+      List.map
+        (fun (pagenum, page) ->
+           if mem pagenum range then
+             (if isbefore then padpages @ [page] else [page] @ padpages)
+           else
+             [page])
+        (combine (indx original_pages) original_pages)
+    in
+      (* FIXME Provide ~changes here? *)
+      Pdfpage.change_pages false merged (flatten newpages)
 
 let pad padwith range pdf isbefore =
   match padwith with
diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 4a3fe67..1e9cbde 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -3787,7 +3787,12 @@ let go () =
           | [] -> []
           | l -> if last l = Pdfpage.endpage pdf then all_but_last l else l
         in
-          write_pdf false (Cpdf.padafter range pdf)
+          let padwith =
+            match args.padwith with
+              None -> None
+            | Some filename -> Some (pdfread_pdf_of_file None None filename)
+          in
+            write_pdf false (Cpdf.padafter ?padwith range pdf)
   | Some (PadMultiple n) ->
       let pdf = get_single_pdf args.op false in
         write_pdf false (Cpdf.padmultiple n pdf)
diff --git a/cpdfmanual.tex b/cpdfmanual.tex
index d775f7c..7b674ec 100644
--- a/cpdfmanual.tex
+++ b/cpdfmanual.tex
@@ -3,6 +3,7 @@
 %FIXME: Document %PageDiv2
 %FIXME: Document new bookmark format
 %FIXME: Fix docs on -fit-window and friends
+%FIXME: Document new -pad-with (for -pad-before, -pad-after, -pad-every)
 \documentclass{book}
 \usepackage{palatino}
 \usepackage{microtype}