diff --git a/hgext/show.py b/hgext/show.py
--- a/hgext/show.py
+++ b/hgext/show.py
@@ -397,7 +397,8 @@
     revdag = graphmod.dagwalker(repo, revs)
 
     ui.setconfig('experimental', 'graphshorten', True)
-    cmdutil.displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges)
+    cmdutil.displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges,
+                         widthfn=graphmod.asciiwidth)
 
 def extsetup(ui):
     # Alias `hg <prefix><view>` to `hg show <view>`.
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -2508,7 +2508,7 @@
     return formatnode
 
 def displaygraph(ui, repo, dag, displayer, edgefn, getrenamed=None,
-                 filematcher=None):
+                 filematcher=None, widthfn=None):
     formatnode = _graphnodeformatter(ui, displayer)
     state = graphmod.asciistate()
     styles = state['styles']
@@ -2545,7 +2545,11 @@
         revmatchfn = None
         if filematcher is not None:
             revmatchfn = filematcher(ctx.rev())
-        displayer.show(ctx, copies=copies, matchfn=revmatchfn)
+        graphwidth = 0
+        if widthfn:
+            graphwidth = widthfn(state, rev, parents)
+        displayer.show(ctx, copies=copies, matchfn=revmatchfn,
+                       _graphwidth=graphwidth)
         lines = displayer.hunk.pop(rev).split('\n')
         if not lines[-1]:
             del lines[-1]
@@ -2570,7 +2574,7 @@
     ui.pager('log')
     displayer = show_changeset(ui, repo, opts, buffered=True)
     displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges, getrenamed,
-                 filematcher)
+                 filematcher, widthfn=graphmod.asciiwidth)
 
 def checkunsupportedgraphflags(pats, opts):
     for op in ["newest_first"]:
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -3123,7 +3123,8 @@
         def display(other, chlist, displayer):
             revdag = cmdutil.graphrevs(other, chlist, opts)
             cmdutil.displaygraph(ui, repo, revdag, displayer,
-                                 graphmod.asciiedges)
+                                 graphmod.asciiedges,
+                                 widthfn=graphmod.asciiwidth)
 
         hg._incoming(display, lambda: 1, ui, repo, source, opts, buffered=True)
         return 0
@@ -3572,7 +3573,8 @@
         revdag = cmdutil.graphrevs(repo, o, opts)
         ui.pager('outgoing')
         displayer = cmdutil.show_changeset(ui, repo, opts, buffered=True)
-        cmdutil.displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges)
+        cmdutil.displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges,
+                             widthfn=graphmod.asciiwidth)
         cmdutil.outgoinghooks(ui, repo, other, opts, o)
         return 0
 
diff --git a/mercurial/graphmod.py b/mercurial/graphmod.py
--- a/mercurial/graphmod.py
+++ b/mercurial/graphmod.py
@@ -222,6 +222,24 @@
     state['edges'].pop(rev, None)
     yield (type, char, lines, (nodeidx, edges, ncols, nmorecols))
 
+def asciiwidth(state, rev, parents):
+    """returns the width of the graph drawn by ascii() based on asciiedges()"""
+    seen = state['seen'][:]
+    if rev not in seen:
+        seen.append(rev)
+    columns = len(seen)
+
+    # We might be adding columns to handle previously unseen parents, but only
+    # one of them goes into the graph width for this rev.
+    newparents = 0
+    for ptype, parent in parents:
+        if parent != rev and parent not in seen:
+            newparents += 1
+    columns = max(columns, columns + min(2, newparents) - 1)
+
+    # Each column is 2 characters, and there's another character of padding.
+    return 1 + 2 * columns
+
 def _fixlongrightedges(edges):
     for (i, (start, end)) in enumerate(edges):
         if end > start:
diff --git a/mercurial/templatekw.py b/mercurial/templatekw.py
--- a/mercurial/templatekw.py
+++ b/mercurial/templatekw.py
@@ -764,6 +764,13 @@
     """Integer. The width of the current terminal."""
     return repo.ui.termwidth()
 
+@templatekeyword('graphwidth')
+def graphwidth(repo, ctx, templ, **args):
+    """Integer. The width of the graph drawn by 'log --graph' or zero."""
+    # The value args['graphwidth'] will be this function, so we use an internal
+    # name to pass the value through props into this function.
+    return args.get('_graphwidth', 0)
+
 @templatekeyword('troubles')
 def showtroubles(**args):
     """List of strings. Evolution troubles affecting the changeset.
diff --git a/tests/test-command-template.t b/tests/test-command-template.t
--- a/tests/test-command-template.t
+++ b/tests/test-command-template.t
@@ -4319,3 +4319,155 @@
   custom
 
   $ cd ..
+
+Test 'graphwidth' in 'hg log' on various topologies. The key here is that the
+printed graphwidths 3, 5, 7, etc. should all line up in their respective
+columns. We don't care about other aspects of the graph rendering here.
+
+  $ hg init graphwidth
+  $ cd graphwidth
+
+  $ wrappabletext="a a a a a a a a a a a a"
+
+  $ printf "first\n" > file
+  $ hg add file
+  $ hg commit -m "$wrappabletext"
+
+  $ printf "first\nsecond\n" > file
+  $ hg commit -m "$wrappabletext"
+
+  $ hg checkout 0
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ printf "third\nfirst\n" > file
+  $ hg commit -m "$wrappabletext"
+  created new head
+
+  $ hg merge
+  merging file
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+
+  $ hg log --graph -T "{graphwidth}"
+  @  3
+  |
+  | @  5
+  |/
+  o  3
+  
+  $ hg commit -m "$wrappabletext"
+
+  $ hg log --graph -T "{graphwidth}"
+  @    5
+  |\
+  | o  5
+  | |
+  o |  5
+  |/
+  o  3
+  
+
+  $ hg checkout 0
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ printf "third\nfirst\nsecond\n" > file
+  $ hg commit -m "$wrappabletext"
+  created new head
+
+  $ hg log --graph -T "{graphwidth}"
+  @  3
+  |
+  | o    7
+  | |\
+  +---o  7
+  | |
+  | o  5
+  |/
+  o  3
+  
+
+  $ hg log --graph -T "{graphwidth}" -r 3
+  o    5
+  |\
+  ~ ~
+
+  $ hg log --graph -T "{graphwidth}" -r 1
+  o  3
+  |
+  ~
+
+  $ hg merge
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg commit -m "$wrappabletext"
+
+  $ printf "seventh\n" >> file
+  $ hg commit -m "$wrappabletext"
+
+  $ hg log --graph -T "{graphwidth}"
+  @  3
+  |
+  o    5
+  |\
+  | o  5
+  | |
+  o |    7
+  |\ \
+  | o |  7
+  | |/
+  o /  5
+  |/
+  o  3
+  
+
+The point of graphwidth is to allow wrapping that accounts for the space taken
+by the graph.
+
+  $ COLUMNS=10 hg log --graph -T "{fill(desc, termwidth - graphwidth)}"
+  @  a a a a
+  |  a a a a
+  |  a a a a
+  o    a a a
+  |\   a a a
+  | |  a a a
+  | |  a a a
+  | o  a a a
+  | |  a a a
+  | |  a a a
+  | |  a a a
+  o |    a a
+  |\ \   a a
+  | | |  a a
+  | | |  a a
+  | | |  a a
+  | | |  a a
+  | o |  a a
+  | |/   a a
+  | |    a a
+  | |    a a
+  | |    a a
+  | |    a a
+  o |  a a a
+  |/   a a a
+  |    a a a
+  |    a a a
+  o  a a a a
+     a a a a
+     a a a a
+
+Something tricky happens when there are elided nodes; the next drawn row of
+edges can be more than one column wider, but the graph width only increases by
+one column. The remaining columns are added in between the nodes.
+
+  $ hg log --graph -T "{graphwidth}" -r "0|2|4|5"
+  o    5
+  |\
+  | \
+  | :\
+  o : :  7
+  :/ /
+  : o  5
+  :/
+  o  3
+  
+
+  $ cd ..
+