diff --git a/lisp/icomplete.el b/lisp/icomplete.el
index 4e546807b7..2fe740292c 100644
--- a/lisp/icomplete.el
+++ b/lisp/icomplete.el
@@ -687,33 +687,32 @@ icomplete-completions
              ;; a prefix of most, or something else.
 	     (compare (compare-strings name nil nil
 				       most nil nil completion-ignore-case))
-	     (ellipsis (if (char-displayable-p ?…) "…" "..."))
 	     (determ (unless (or (eq t compare) (eq t most-try)
 				 (= (setq compare (1- (abs compare)))
 				    (length most)))
 		       (concat open-bracket
-			       (cond
-				((= compare (length name))
+                               ;; Don't bother truncating if it doesn't gain
+                               ;; us at least 2 columns.
+                               (if (< compare 2)
+                                   most
                                  ;; Typical case: name is a prefix.
-				 (substring most compare))
-                                ;; Don't bother truncating if it doesn't gain
-                                ;; us at least 2 columns.
-				((< compare (+ 2 (string-width ellipsis))) most)
-				(t (concat ellipsis (substring most compare))))
+                                 (substring most compare))
 			       close-bracket)))
+             (vertical (string-match "\n" icomplete-separator))
 	     ;;"-prospects" - more than one candidate
-	     (prospects-len (+ (string-width
-				(or determ (concat open-bracket close-bracket)))
-			       (string-width icomplete-separator)
-			       (+ 2 (string-width ellipsis)) ;; take {…} into account
-			       (string-width (buffer-string))))
+	     (prospects-len (unless vertical
+                              (+ (string-width
+				  (if determ (concat determ "{") open-bracket))
+			         (string-width (buffer-string)))))
              (prospects-max
-              ;; Max total length to use, including the minibuffer content.
-              (* (+ icomplete-prospects-height
-                    ;; If the minibuffer content already uses up more than
-                    ;; one line, increase the allowable space accordingly.
-                    (/ prospects-len (window-width)))
-                 (window-width)))
+              (if vertical
+                  icomplete-prospects-height
+                ;; Max total length to use, including the minibuffer content.
+                (* (+ icomplete-prospects-height
+                      ;; If the minibuffer content already uses up more than
+                      ;; one line, increase the allowable space accordingly.
+                      (/ prospects-len (window-width)))
+                   (window-width))))
              ;; Find the common prefix among `comps'.
              ;; We can't use the optimization below because its assumptions
              ;; aren't always true, e.g. when completion-cycling (bug#10850):
@@ -730,7 +729,9 @@ icomplete-completions
                    ;; is already displayed via `most'.
                    (string-prefix-p prefix most t)
                    (length prefix))) ;;)
-	     prospects comp limit)
+             (limit (when vertical
+                      (> (length comps) prospects-max)))
+	     prospects comp)
 	(if (or (eq most-try t) (not (consp (cdr comps))))
 	    (setq prospects nil)
 	  (when (member name comps)
@@ -753,24 +754,38 @@ icomplete-completions
 	    ;; completion field.
 	    (setq determ (concat open-bracket "" close-bracket)))
 	  ;; Compute prospects for display.
-	  (while (and comps (not limit))
-	    (setq comp
-		  (if prefix-len (substring (car comps) prefix-len) (car comps))
-		  comps (cdr comps))
-	    (setq prospects-len
-                  (+ (string-width comp)
-		     (string-width icomplete-separator)
-		     prospects-len))
-	    (if (< prospects-len prospects-max)
-		(push comp prospects)
-	      (setq limit t))))
-	(setq prospects (nreverse prospects))
-	;; Decorate first of the prospects.
-	(when prospects
-	  (let ((first (copy-sequence (pop prospects))))
-	    (put-text-property 0 (length first)
-			       'face 'icomplete-first-match first)
-	    (push first prospects)))
+	  (if vertical
+              (while (and comps (> prospects-max 0))
+                (setq prospects-max (1- prospects-max))
+                (push (if prefix-len
+                          (substring (pop comps) prefix-len)
+                        (pop comps))
+                      prospects))
+            (while (and comps (not limit))
+	      (setq comp (if prefix-len
+                             (substring (pop comps) prefix-len)
+                           (pop comps)))
+              (setq prospects-len
+                    (+ (string-width comp)
+                       prospects-len))
+              ;; There be the } after last comp.  Add 1 to prospects-len if last comp.
+              (if (<= (+ (if comps 0 1) prospects-len) prospects-max)
+                  (push comp prospects)
+                (setq limit t))
+              ;; Add separator if there are more comps
+              (when (and comps (not limit))
+                (setq prospects-len
+                      (+ (string-width icomplete-separator)
+                         prospects-len))
+                (unless (<= prospects-len prospects-max)
+                  (setq limit t)))))
+	  (when prospects
+	    (setq prospects (nreverse prospects))
+	    ;; Decorate first of the prospects.
+	    (let ((first (copy-sequence (pop prospects))))
+	      (put-text-property 0 (length first)
+			         'face 'icomplete-first-match first)
+	      (push first prospects))))
         ;; Restore the base-size info, since completion-all-sorted-completions
         ;; is cached.
         (if last (setcdr last base-size))
@@ -778,8 +793,7 @@ icomplete-completions
 	    (concat determ
 		    "{"
 		    (mapconcat 'identity prospects icomplete-separator)
-		    (and limit (concat icomplete-separator ellipsis))
-		    "}")
+                    (unless limit "}"))
 	  (concat determ " [Matched]"))))))
 
 ;;; Iswitchb compatibility