Runic inscription:

Sven had the stones raised after . . ., his father.
Öpir carved..

Suain ' [lit] …ais- [·] st(a)ina …f… …ah ' faþur sin [·]
YbiR [·] risti
 

Runecarver: Öpir
Öpir has been credited with the most runestones of all rune carvers, perhaps more than is possible... it seems that he often fabricated his commissions, sketched and taught the craft and then let the farm workers do the remaining work. But this one in particular he most likely carved himself.

But small details (see info in the top image) reveal that this particular runestone was indeed carved by Öpir himself on site or by his collaborators and followers.

A detail in the runic inscription: "staina", (the stones) is interesting because then there would have been more of Öpir at the site... and perhaps there is still some because on the north side of the sacristy there are two fragments of carvings in red sandstone, both with a cross and one with a small round animal on it.

None of the crosses resemble those that Öpir usually uses and the small round animal (which is too small to be good) is probably just an experiment. Perhaps both of these pieces are experiments of some local ability that was inspired by Öpir's work at the site, for example. In that case we are back to square one with the word "stones", then there is another runestone nearby that is carved by Öpir, a runestone that has not yet been discovered.

In Ekerö municipality, Öpir has also carved the runestone U 36, Svartsjö djurgård, which is actually not that far from here, although usually much more difficult to access as it stands on a field island with crops around it. But I do not think that is the runestone referred to in the runic inscription.

Links

Upplands runinskrifter > page 31
(Only Swedish)

Wikipedia about Öpir >

Runor >  Riksantikvarieämbetet
(National Antiquities Board, mostly Swedish)

Google map > Find the runestone and the church

About Hilleshögs church >
(Only about the church and only in Swedish)
 

ALL RUNESTONES

Ekerö municipality

ADELSÖ >
has 5 known runestones

BIRKA >
has fragments from 9 known runestones

MUNSÖ >
has 3 or 4 known runestones

EKERÖ >
has 11 known runestones

FÄRINGSÖ >
has 27 known runestones

LOVÖ >
has 8 known runestones