These are the chords for John Mayer's cover of Beyonce's XO that he played in Adelaide, South Australia
on the 15th of April 2014. I was there and it was amazing. 

Here is a link to a YouTube video of it: http://www.youtube.com/watch?v=JVH6OkUT7Dc

I worked this out from my recording of it and the YouTube video

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                             XO - John Mayer
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Tabbed by: Brenton Chattin
E-mail: brenton.chattin@gmail.com

Tuning: Standard, Capo 2nd

These are the chords used, pretty much just mix it up by hammering on the B string from open to 1st throughout.

I'm not sure about the proper name for the chords but they are all relative to the Capo

    C              G            Am  (or C6?) 
e|--3---|      e|--3--|     e|---3--|        
B|--1---|      B|--1--|     B|---1--|
G|--0---|      G|--0--|     G|---2--|
D|--2---|      D|--0--|     D|---2--|
A|--3---|      A|--2--|     A|---0--|
E|------|      E|--3--|     E|------|


C
Your love is bright as ever 
C
Even in the shadows
G
Baby, kiss me
G                               C
Before they turn the lights out
C
Your heart is glowing
C
And I'm crashing into you
       G
Baby, kiss me
                              C
Before they turn the lights out 
C
Before they turn the lights out
C
Baby, love me lights out

C
In the darkest night hour 
Am
I'll search through the crowd 
             G
Your face is all that I see
G
I'll give you everything
                       C
Baby, love me lights out

C
We don't have forever
Am
Ooh, baby daylight's wasting 
G
You better kiss me 
C
Before our time has run out
C
Ooohhh
C
Nobody sees what we see
Am
They're just hopelessly gazing
        G
Oh baby, take me, take me
                              C
Before they turn the lights out
C
Before our time has run out
C
Baby, love me lights out


C
In the darkest night hour 
Am
I'll search through the crowd 
             G
Your face is all that I see
G
I'll give you everything
              C   
Baby, love me lights out
C
Baby, love me lights out

C
I love you like XO
C
You love me like XO
Am
You kill me girl XO
Am
You love me like XO
G
All that I see
G
Give me everything
G
Baby, love me lights out
C
Baby, love me lights out

C, G, Am, C

C
In the darkest night hour 
Am
I'll search through the crowd 
G
Your face is all that I see
G
I'll give you everything
C
Baby, love me lights out
C
Baby, love me lights out
C
You can turn my lights out

End on C


The timing of the chords might be slightly off but it's so easy you should be able to work it out 
pretty quickly!

Cheers,

Brenton