diff --git a/git-gui/Makefile b/git-gui/Makefile
index f10caedaa7..d529cab820 100644
--- a/git-gui/Makefile
+++ b/git-gui/Makefile
@@ -293,6 +293,7 @@ install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
 	$(QUIET)$(INSTALL_X0)git-gui $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(INSTALL_X0)git-gui--askpass $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
+	$(QUIET)$(INSTALL_X0)git-gui--askyesno $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(DESTDIR_SQ)$(gitexecdir_SQ)/git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(INSTALL_R0)git-gui.tcl $(INSTALL_R1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
@@ -311,6 +312,7 @@ uninstall:
 	$(QUIET)$(CLEAN_DST) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui $(REMOVE_F1)
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askpass $(REMOVE_F1)
+	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askyesno $(REMOVE_F1)
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/$p $(REMOVE_F1) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui.tcl $(REMOVE_F1)
diff --git a/git-gui/git-gui--askyesno b/git-gui/git-gui--askyesno
new file mode 100755
index 0000000000..c0c82e7cbd
--- /dev/null
+++ b/git-gui/git-gui--askyesno
@@ -0,0 +1,68 @@
+#!/bin/sh
+# Tcl ignores the next line -*- tcl -*- \
+exec wish "$0" -- "$@"
+
+# This is an implementation of a simple yes no dialog
+# which is injected into the git commandline by git gui
+# in case a yesno question needs to be answered.
+
+set NS {}
+set use_ttk [package vsatisfies [package provide Tk] 8.5]
+if {$use_ttk} {
+	set NS ttk
+}
+
+set title "Question?"
+if {$argc < 1} {
+	puts stderr "Usage: $argv0 <question>"
+	exit 1
+} else {
+	if {$argc > 2 && [lindex $argv 0] == "--title"} {
+		set title [lindex $argv 1]
+		set argv [lreplace $argv 0 1]
+	}
+	set prompt [join $argv " "]
+}
+
+${NS}::frame .t
+${NS}::label .t.m -text $prompt -justify center -width 400px
+.t.m configure -wraplength 400px
+pack .t.m -side top -fill x -padx 20 -pady 20 -expand 1
+pack .t -side top -fill x -ipadx 20 -ipady 20 -expand 1
+
+${NS}::frame .b
+${NS}::frame .b.left -width 200
+${NS}::button .b.yes -text Yes -command yes
+${NS}::button .b.no  -text No  -command no
+
+
+pack .b.left -side left -expand 1 -fill x
+pack .b.yes -side left -expand 1
+pack .b.no -side right -expand 1 -ipadx 5
+pack .b -side bottom -fill x -ipadx 20 -ipady 15
+
+bind . <Key-Return> {exit 0}
+bind . <Key-Escape> {exit 1}
+
+proc no {} {
+	exit 1
+}
+
+proc yes {} {
+	exit 0
+}
+
+if {$::tcl_platform(platform) eq {windows}} {
+	set icopath [file dirname [file normalize $argv0]]
+	if {[file tail $icopath] eq {git-core}} {
+		set icopath [file dirname $icopath]
+	}
+	set icopath [file dirname $icopath]
+	set icopath [file join $icopath share git git-for-windows.ico]
+	if {[file exists $icopath]} {
+		wm iconbitmap . -default $icopath
+	}
+}
+
+wm title . $title
+tk::PlaceWindow .
diff --git a/git-gui/git-gui.sh b/git-gui/git-gui.sh
index 6de74ce639..1fc1642d88 100755
--- a/git-gui/git-gui.sh
+++ b/git-gui/git-gui.sh
@@ -623,7 +623,11 @@ proc git_write {args} {
 }
 
 proc githook_read {hook_name args} {
-	set pchook [gitdir hooks $hook_name]
+	if {[package vcompare $::_git_version 2.5.0] >= 0} {
+		set pchook [git rev-parse --git-path "hooks/$hook_name"]
+	} else {
+		set pchook [gitdir hooks $hook_name]
+	}
 	lappend args 2>@1
 
 	# On Windows [file executable] might lie so we need to ask
@@ -1229,6 +1233,12 @@ set have_tk85 [expr {[package vcompare $tk_version "8.5"] >= 0}]
 if {![info exists env(SSH_ASKPASS)]} {
 	set env(SSH_ASKPASS) [gitexec git-gui--askpass]
 }
+if {![info exists env(GIT_ASKPASS)]} {
+	set env(GIT_ASKPASS) [gitexec git-gui--askpass]
+}
+if {![info exists env(GIT_ASK_YESNO)]} {
+	set env(GIT_ASK_YESNO) [gitexec git-gui--askyesno]
+}
 
 ######################################################################
 ##
@@ -1325,9 +1335,6 @@ if {[lindex $_reponame end] eq {.git}} {
 	set _reponame [lindex $_reponame end]
 }
 
-set env(GIT_DIR) $_gitdir
-set env(GIT_WORK_TREE) $_gitworktree
-
 ######################################################################
 ##
 ## global init
@@ -2152,7 +2159,7 @@ set starting_gitk_msg [mc "Starting gitk... please wait..."]
 
 proc do_gitk {revs {is_submodule false}} {
 	global current_diff_path file_states current_diff_side ui_index
-	global _gitdir _gitworktree
+	global _gitworktree
 
 	# -- Always start gitk through whatever we were loaded with.  This
 	#    lets us bypass using shell process on Windows systems.
@@ -2164,12 +2171,19 @@ proc do_gitk {revs {is_submodule false}} {
 	} else {
 		global env
 
+		if {[info exists env(GIT_DIR)]} {
+			set old_GIT_DIR $env(GIT_DIR)
+		} else {
+			set old_GIT_DIR {}
+		}
+
 		set pwd [pwd]
 
 		if {!$is_submodule} {
 			if {![is_bare]} {
 				cd $_gitworktree
 			}
+			set env(GIT_DIR) [file normalize [gitdir]]
 		} else {
 			cd $current_diff_path
 			if {$revs eq {--}} {
@@ -2190,18 +2204,17 @@ proc do_gitk {revs {is_submodule false}} {
 				}
 				set revs $old_sha1...$new_sha1
 			}
-			# GIT_DIR and GIT_WORK_TREE for the submodule are not the ones
-			# we've been using for the main repository, so unset them.
-			# TODO we could make life easier (start up faster?) for gitk
-			# by setting these to the appropriate values to allow gitk
-			# to skip the heuristics to find their proper value
-			unset env(GIT_DIR)
-			unset env(GIT_WORK_TREE)
+			if {[info exists env(GIT_DIR)]} {
+				unset env(GIT_DIR)
+			}
 		}
 		eval exec $cmd $revs "--" "--" &
 
-		set env(GIT_DIR) $_gitdir
-		set env(GIT_WORK_TREE) $_gitworktree
+		if {$old_GIT_DIR ne {}} {
+			set env(GIT_DIR) $old_GIT_DIR
+		} else {
+			unset env(GIT_DIR)
+		}
 		cd $pwd
 
 		ui_status $::starting_gitk_msg
@@ -2222,20 +2235,22 @@ proc do_git_gui {} {
 		error_popup [mc "Couldn't find git gui in PATH"]
 	} else {
 		global env
-		global _gitdir _gitworktree
 
-		# see note in do_gitk about unsetting these vars when
-		# running tools in a submodule
-		unset env(GIT_DIR)
-		unset env(GIT_WORK_TREE)
+		if {[info exists env(GIT_DIR)]} {
+			set old_GIT_DIR $env(GIT_DIR)
+			unset env(GIT_DIR)
+		} else {
+			set old_GIT_DIR {}
+		}
 
 		set pwd [pwd]
 		cd $current_diff_path
 
 		eval exec $exe gui &
 
-		set env(GIT_DIR) $_gitdir
-		set env(GIT_WORK_TREE) $_gitworktree
+		if {$old_GIT_DIR ne {}} {
+			set env(GIT_DIR) $old_GIT_DIR
+		}
 		cd $pwd
 
 		ui_status $::starting_gitk_msg
@@ -2706,10 +2721,18 @@ if {![is_bare]} {
 }
 
 if {[is_Windows]} {
+	# Use /git-bash.exe if available
+	set normalized [file normalize $::argv0]
+	regsub "/mingw../libexec/git-core/git-gui$" \
+		$normalized "/git-bash.exe" cmdLine
+	if {$cmdLine != $normalized && [file exists $cmdLine]} {
+		set cmdLine [list "Git Bash" $cmdLine &]
+	} else {
+		set cmdLine [list "Git Bash" bash --login -l &]
+	}
 	.mbar.repository add command \
 		-label [mc "Git Bash"] \
-		-command {eval exec [auto_execok start] \
-					  [list "Git Bash" bash --login -l &]}
+		-command {eval exec [auto_execok start] $cmdLine}
 }
 
 if {[is_Windows] || ![is_bare]} {
diff --git a/gitk-git/gitk b/gitk-git/gitk
index a14d7a16b2..d1d77d832e 100755
--- a/gitk-git/gitk
+++ b/gitk-git/gitk
@@ -406,7 +406,7 @@ proc start_rev_list {view} {
 	if {$revs eq {}} {
 	    return 0
 	}
-	set args [concat $vflags($view) $revs]
+	set args [limit_arg_length [concat $vflags($view) $revs]]
     } else {
 	set args $vorigargs($view)
     }
@@ -2076,7 +2076,7 @@ proc makewindow {} {
     global headctxmenu progresscanv progressitem progresscoords statusw
     global fprogitem fprogcoord lastprogupdate progupdatepending
     global rprogitem rprogcoord rownumsel numcommits
-    global have_tk85 use_ttk NS
+    global have_tk85 have_tk86 use_ttk NS
     global git_version
     global worddiff
 
@@ -2566,8 +2566,13 @@ proc makewindow {} {
     bind . <Key-Down> "selnextline 1"
     bind . <Shift-Key-Up> "dofind -1 0"
     bind . <Shift-Key-Down> "dofind 1 0"
-    bindkey <Key-Right> "goforw"
-    bindkey <Key-Left> "goback"
+    if {$have_tk86} {
+        bindkey <<NextChar>> "goforw"
+        bindkey <<PrevChar>> "goback"
+    } else {
+        bindkey <Key-Right> "goforw"
+        bindkey <Key-Left> "goback"
+    }
     bind . <Key-Prior> "selnextpage -1"
     bind . <Key-Next> "selnextpage 1"
     bind . <$M1B-Home> "allcanvs yview moveto 0.0"
@@ -7634,7 +7639,7 @@ proc gettreeline {gtf id} {
 	if {[string index $fname 0] eq "\""} {
 	    set fname [lindex $fname 0]
 	}
-	set fname [encoding convertfrom $fname]
+	set fname [encoding convertfrom utf-8 $fname]
 	lappend treefilelist($id) $fname
     }
     if {![eof $gtf]} {
@@ -7896,7 +7901,7 @@ proc gettreediffline {gdtf ids} {
 	    if {[string index $file 0] eq "\""} {
 		set file [lindex $file 0]
 	    }
-	    set file [encoding convertfrom $file]
+	    set file [encoding convertfrom utf-8 $file]
 	    if {$file ne [lindex $treediff end]} {
 		lappend treediff $file
 		lappend sublist $file
@@ -8041,7 +8046,7 @@ proc makediffhdr {fname ids} {
     global ctext curdiffstart treediffs diffencoding
     global ctext_file_names jump_to_here targetline diffline
 
-    set fname [encoding convertfrom $fname]
+    set fname [encoding convertfrom utf-8 $fname]
     set diffencoding [get_path_encoding $fname]
     set i [lsearch -exact $treediffs($ids) $fname]
     if {$i >= 0} {
@@ -8103,7 +8108,7 @@ proc parseblobdiffline {ids line} {
 
     if {![string compare -length 5 "diff " $line]} {
 	if {![regexp {^diff (--cc|--git) } $line m type]} {
-	    set line [encoding convertfrom $line]
+	    set line [encoding convertfrom utf-8 $line]
 	    $ctext insert end "$line\n" hunksep
 	    continue
 	}
@@ -8150,7 +8155,7 @@ proc parseblobdiffline {ids line} {
 	makediffhdr $fname $ids
 
     } elseif {![string compare -length 16 "* Unmerged path " $line]} {
-	set fname [encoding convertfrom [string range $line 16 end]]
+	set fname [encoding convertfrom utf-8 [string range $line 16 end]]
 	$ctext insert end "\n"
 	set curdiffstart [$ctext index "end - 1c"]
 	lappend ctext_file_names $fname
@@ -8205,7 +8210,7 @@ proc parseblobdiffline {ids line} {
 	    if {[string index $fname 0] eq "\""} {
 		set fname [lindex $fname 0]
 	    }
-	    set fname [encoding convertfrom $fname]
+	    set fname [encoding convertfrom utf-8 $fname]
 	    set i [lsearch -exact $treediffs($ids) $fname]
 	    if {$i >= 0} {
 		setinlist difffilestart $i $curdiffstart
@@ -8224,6 +8229,7 @@ proc parseblobdiffline {ids line} {
 	    set diffinhdr 0
 	    return
 	}
+	set line [encoding convertfrom utf-8 $line]
 	$ctext insert end "$line\n" filesep
 
     } else {
@@ -9982,7 +9988,7 @@ proc showrefs {} {
     text $top.list -background $bgcolor -foreground $fgcolor \
 	-selectbackground $selectbgcolor -font mainfont \
 	-xscrollcommand "$top.xsb set" -yscrollcommand "$top.ysb set" \
-	-width 30 -height 20 -cursor $maincursor \
+	-width 60 -height 20 -cursor $maincursor \
 	-spacing1 1 -spacing3 1 -state disabled
     $top.list tag configure highlight -background $selectbgcolor
     if {![lsearch -exact $bglist $top.list]} {
@@ -10171,7 +10177,8 @@ proc getallcommits {} {
 	}
     }
     if {$ids ne {}} {
-	set fd [open [concat $cmd $ids] r]
+	set cmd [limit_arg_length [concat $cmd $ids]]
+	set fd [open $cmd r]
 	fconfigure $fd -blocking 0
 	incr allcommits
 	nowbusy allcommits
@@ -10181,6 +10188,21 @@ proc getallcommits {} {
     }
 }
 
+# The maximum command line length for the CreateProcess function is 32767 characters, see
+# http://blogs.msdn.com/oldnewthing/archive/2003/12/10/56028.aspx
+# Be a little conservative in case Tcl adds some more stuff to the command line we do not
+# know about and truncate the command line at a SHA1-boundary below 32000 characters.
+proc limit_arg_length {cmd} {
+    if {[tk windowingsystem] == "win32" &&
+       [string length $cmd] > 32000} {
+        set ndx [string last " " $cmd 32000]
+        if {$ndx != -1} {
+            return [string range $cmd 0 $ndx]
+        }
+    }
+    return $cmd
+}
+
 # Since most commits have 1 parent and 1 child, we group strings of
 # such commits into "arcs" joining branch/merge points (BMPs), which
 # are commits that either don't have 1 parent or don't have 1 child.
@@ -12161,7 +12183,7 @@ proc cache_gitattr {attr pathlist} {
 	    foreach row [split $rlist "\n"] {
 		if {[regexp "(.*): $attr: (.*)" $row m path value]} {
 		    if {[string index $path 0] eq "\""} {
-			set path [encoding convertfrom [lindex $path 0]]
+			set path [encoding convertfrom utf-8 [lindex $path 0]]
 		    }
 		    set path_attr_cache($attr,$path) $value
 		}
@@ -12191,7 +12213,6 @@ if { [info exists ::env(GITK_MSGSDIR)] } {
     set gitk_prefix [file dirname [file dirname [file normalize $argv0]]]
     set gitk_libdir [file join $gitk_prefix share gitk lib]
     set gitk_msgsdir [file join $gitk_libdir msgs]
-    unset gitk_prefix
 }
 
 ## Internationalization (i18n) through msgcat and gettext. See
@@ -12482,6 +12503,7 @@ set nullid2 "0000000000000000000000000000000000000001"
 set nullfile "/dev/null"
 
 set have_tk85 [expr {[package vcompare $tk_version "8.5"] >= 0}]
+set have_tk86 [expr {[package vcompare $tk_version "8.6"] >= 0}]
 if {![info exists have_ttk]} {
     set have_ttk [llength [info commands ::ttk::style]]
 }
@@ -12546,28 +12568,32 @@ if {[expr {[exec git rev-parse --is-inside-work-tree] == "true"}]} {
 set worktree [exec git rev-parse --show-toplevel]
 setcoords
 makewindow
-catch {
-    image create photo gitlogo      -width 16 -height 16
+if {$::tcl_platform(platform) eq {windows} && [file exists $gitk_prefix/etc/git.ico]} {
+    wm iconbitmap . -default $gitk_prefix/etc/git.ico
+} else {
+    catch {
+        image create photo gitlogo      -width 16 -height 16
 
-    image create photo gitlogominus -width  4 -height  2
-    gitlogominus put #C00000 -to 0 0 4 2
-    gitlogo copy gitlogominus -to  1 5
-    gitlogo copy gitlogominus -to  6 5
-    gitlogo copy gitlogominus -to 11 5
-    image delete gitlogominus
+        image create photo gitlogominus -width  4 -height  2
+        gitlogominus put #C00000 -to 0 0 4 2
+        gitlogo copy gitlogominus -to  1 5
+        gitlogo copy gitlogominus -to  6 5
+        gitlogo copy gitlogominus -to 11 5
+        image delete gitlogominus
 
-    image create photo gitlogoplus  -width  4 -height  4
-    gitlogoplus  put #008000 -to 1 0 3 4
-    gitlogoplus  put #008000 -to 0 1 4 3
-    gitlogo copy gitlogoplus  -to  1 9
-    gitlogo copy gitlogoplus  -to  6 9
-    gitlogo copy gitlogoplus  -to 11 9
-    image delete gitlogoplus
+        image create photo gitlogoplus  -width  4 -height  4
+        gitlogoplus  put #008000 -to 1 0 3 4
+        gitlogoplus  put #008000 -to 0 1 4 3
+        gitlogo copy gitlogoplus  -to  1 9
+        gitlogo copy gitlogoplus  -to  6 9
+        gitlogo copy gitlogoplus  -to 11 9
+        image delete gitlogoplus
 
-    image create photo gitlogo32    -width 32 -height 32
-    gitlogo32 copy gitlogo -zoom 2 2
+        image create photo gitlogo32    -width 32 -height 32
+        gitlogo32 copy gitlogo -zoom 2 2
 
-    wm iconphoto . -default gitlogo gitlogo32
+        wm iconphoto . -default gitlogo gitlogo32
+    }
 }
 # wait for the window to become visible
 tkwait visibility .