diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -2652,14 +2652,18 @@
         revmatchfn = None
         if filematcher is not None:
             revmatchfn = filematcher(ctx.rev())
-        displayer.show(ctx, copies=copies, matchfn=revmatchfn)
+        edges = edgefn(type, char, state, rev, parents)
+        firstedge = next(edges)
+        width = firstedge[2]
+        displayer.show(ctx, copies=copies, matchfn=revmatchfn,
+                       _graphwidth=width)
         lines = displayer.hunk.pop(rev).split('\n')
         if not lines[-1]:
             del lines[-1]
         displayer.flush(ctx)
-        edges = edgefn(type, char, lines, state, rev, parents)
-        for type, char, lines, coldata in edges:
+        for type, char, width, coldata in itertools.chain([firstedge], edges):
             graphmod.ascii(ui, state, type, char, lines, coldata)
+            lines = []
     displayer.close()
 
 def graphlog(ui, repo, pats, opts):
diff --git a/mercurial/graphmod.py b/mercurial/graphmod.py
--- a/mercurial/graphmod.py
+++ b/mercurial/graphmod.py
@@ -172,7 +172,7 @@
         yield (cur, type, data, (col, color), edges)
         seen = next
 
-def asciiedges(type, char, lines, state, rev, parents):
+def asciiedges(type, char, state, rev, parents):
     """adds edge info to changelog DAG walk suitable for ascii()"""
     seen = state['seen']
     if rev not in seen:
@@ -192,6 +192,7 @@
             state['edges'][parent] = state['styles'].get(ptype, '|')
 
     ncols = len(seen)
+    width = 1 + ncols * 2
     nextseen = seen[:]
     nextseen[nodeidx:nodeidx + 1] = newparents
     edges = [(nodeidx, nextseen.index(p)) for p in knownparents]
@@ -205,9 +206,9 @@
         edges.append((nodeidx, nodeidx))
         edges.append((nodeidx, nodeidx + 1))
         nmorecols = 1
-        yield (type, char, lines, (nodeidx, edges, ncols, nmorecols))
+        width += 2
+        yield (type, char, width, (nodeidx, edges, ncols, nmorecols))
         char = '\\'
-        lines = []
         nodeidx += 1
         ncols += 1
         edges = []
@@ -218,9 +219,11 @@
     if len(newparents) > 1:
         edges.append((nodeidx, nodeidx + 1))
     nmorecols = len(nextseen) - ncols
+    if nmorecols > 0:
+        width += 2
     # remove current node from edge characters, no longer needed
     state['edges'].pop(rev, None)
-    yield (type, char, lines, (nodeidx, edges, ncols, nmorecols))
+    yield (type, char, width, (nodeidx, edges, ncols, nmorecols))
 
 def _fixlongrightedges(edges):
     for (i, (start, end)) in enumerate(edges):
diff --git a/mercurial/templatekw.py b/mercurial/templatekw.py
--- a/mercurial/templatekw.py
+++ b/mercurial/templatekw.py
@@ -469,6 +469,13 @@
     else:
         return 'o'
 
+@templatekeyword('graphwidth')
+def showgraphwidth(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('index')
 def showindex(**args):
     """Integer. The current iteration of the loop. (0 indexed)"""
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 ..
+