diff --git a/Makefile.msc b/Makefile.msc
index a2d623e653..3d9d9f2eb2 100644
--- a/Makefile.msc
+++ b/Makefile.msc
@@ -16,6 +16,13 @@ TOP = .
 USE_AMALGAMATION = 1
 !ENDIF
 
+# Set this non-0 to use the library paths and other options necessary for
+# Windows Phone 8.1.
+#
+!IFNDEF USE_WP81_OPTS
+USE_WP81_OPTS = 0
+!ENDIF
+
 # Set this non-0 to split the SQLite amalgamation file into chunks to
 # be used for debugging with Visual Studio.
 #
@@ -132,6 +139,12 @@ OPT_FEATURE_FLAGS = $(OPT_FEATURE_FLAGS) -DSQLITE_ENABLE_COLUMN_METADATA=1
 ############################### END OF OPTIONS ################################
 ###############################################################################
 
+# This assumes that MSVC is always installed in 32-bit Program Files directory
+# and sets the variable for use in locating other 32-bit installs accordingly.
+#
+PROGRAMFILES_X86 = $(VCINSTALLDIR)\..\..
+PROGRAMFILES_X86 = $(PROGRAMFILES_X86:\\=\)
+
 # Check for the predefined command macro CC.  This should point to the compiler
 # binary for the target platform.  If it is not defined, simply define it to
 # the legacy default value 'cl.exe'.
@@ -550,6 +563,33 @@ LTLINKOPTS = $(LTLINKOPTS) "/LIBPATH:$(STORELIBPATH)"
 !ENDIF
 !ENDIF
 
+# When compiling for Windows Phone 8.1, an extra library path is
+# required.
+#
+!IF $(USE_WP81_OPTS)!=0
+!IFNDEF WP81LIBPATH
+!IF "$(PLATFORM)"=="x86"
+WP81LIBPATH = $(PROGRAMFILES_X86)\Windows Phone Kits\8.1\lib\x86
+!ELSEIF "$(PLATFORM)"=="ARM"
+WP81LIBPATH = $(PROGRAMFILES_X86)\Windows Phone Kits\8.1\lib\ARM
+!ELSE
+WP81LIBPATH = $(PROGRAMFILES_X86)\Windows Phone Kits\8.1\lib\x86
+!ENDIF
+!ENDIF
+!ENDIF
+
+# When compiling for Windows Phone 8.1, some extra linker options
+# are also required.
+#
+!IF $(USE_WP81_OPTS)!=0
+!IFDEF WP81LIBPATH
+LTLINKOPTS = $(LTLINKOPTS) "/LIBPATH:$(WP81LIBPATH)"
+!ENDIF
+LTLINKOPTS = $(LTLINKOPTS) /DYNAMICBASE
+LTLINKOPTS = $(LTLINKOPTS) WindowsPhoneCore.lib RuntimeObject.lib PhoneAppModelHost.lib
+LTLINKOPTS = $(LTLINKOPTS) /NODEFAULTLIB:kernel32.lib /NODEFAULTLIB:ole32.lib
+!ENDIF
+
 # If either debugging or symbols are enabled, enable PDBs.
 #
 !IF $(DEBUG)>0 || $(SYMBOLS)!=0
diff --git a/manifest b/manifest
index 8d7389d529..f27c4b1f83 100644
--- a/manifest
+++ b/manifest
@@ -1,9 +1,9 @@
-C Fix\sa\sproblem\swith\sthe\shandling\sof\sdelete\smarkers\sby\sautomerge\son\slarge\sdatabases.
-D 2014-05-15T18:36:39.233
+C Merge\slatest\strunk\schanges\swith\sthis\sbranch.
+D 2014-05-15T19:05:55.306
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in dd2b1aba364ff9b05de41086f74407f285c57670
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
-F Makefile.msc f4b4d99d61cfe4ec508600dccd1a0ab2dc8a8b9b
+F Makefile.msc 52911c6bfeaf9b40f47ef4615ab66d98ab0f2b3d
 F Makefile.vxworks 034289efa9d591b04b1a73598623119c306cbba0
 F README.md 64f270c43c38c46de749e419c22f0ae2f4499fe8
 F VERSION 9f823c026c6a32fc5f84d212a8aae0a221dba45c
@@ -199,7 +199,7 @@ F src/mutex.c d3b66a569368015e0fcb1ac15f81c119f504d3bc
 F src/mutex.h 5bc526e19dccc412b7ff04642f6fdad3fdfdabea
 F src/mutex_noop.c 7682796b7d8d39bf1c138248858efcd10c9e1553
 F src/mutex_unix.c c3a4e00f96ba068a8dbef34084465979aaf369cc
-F src/mutex_w32.c ab08c0fc54b71979370ca7c8f42fc64a9f211ebb
+F src/mutex_w32.c 9bcab6e699fdb20eae784237c36b299830fb3316
 F src/notify.c 976dd0f6171d4588e89e874fcc765e92914b6d30
 F src/os.c 1b147e4cf7cc39e618115c14a086aed44bc91ace
 F src/os.h 60d419395e32a8029fa380a80a3da2e9030f635e
@@ -1144,7 +1144,7 @@ F tool/mksqlite3c-noext.tcl 1712d3d71256ca1f297046619c89e77a4d7c8f6d
 F tool/mksqlite3c.tcl ba274df71f5e6534b0a913c7c48eabfcbd0934b6
 F tool/mksqlite3h.tcl ba24038056f51fde07c0079c41885ab85e2cff12
 F tool/mksqlite3internalh.tcl b6514145a7d5321b47e64e19b8116cc44f973eb1
-F tool/mkvsix.tcl 64805dc0677009f0ba6b6e7199b2f7613cac3ebe
+F tool/mkvsix.tcl 52a4c613707ac34ae9c226e5ccc69cb948556105
 F tool/offsets.c fe4262fdfa378e8f5499a42136d17bf3b98f6091
 F tool/omittest.tcl 34d7ac01fe4fd18e3637f64abe12c40eca0f6b97
 F tool/opcodeDoc.awk b3a2a3d5d3075b8bd90b7afe24283efdd586659c
@@ -1172,7 +1172,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 34f6b4b8e4cb8ea45fd518672dc96335d1ce06ab
-R e26158b3998e23a04d5e7968b1e6dfac
+P 2b09bd17eb85ea3c682e930d2aabc6441f2265e0 0901dccedaf5679691ba803ec76d113de170185d
+R bc36878656a1df406ce5faa15b3690cd
 U dan
-Z 27219917e93f1cfe1a1e1c19124576cc
+Z 7b26c3764a28756f379665cd911542c0
diff --git a/manifest.uuid b/manifest.uuid
index 8f898f62ee..414ca82c34 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-2b09bd17eb85ea3c682e930d2aabc6441f2265e0
\ No newline at end of file
+5809986ffcc5d9cbab64760f8d7fbfbb6b626ee7
\ No newline at end of file
diff --git a/src/mutex_w32.c b/src/mutex_w32.c
index 2eb852413e..f43a152389 100644
--- a/src/mutex_w32.c
+++ b/src/mutex_w32.c
@@ -13,17 +13,19 @@
 */
 #include "sqliteInt.h"
 
+#if SQLITE_OS_WIN
+/*
+** Include the header file for the Windows VFS.
+*/
+#include "os_win.h"
+#endif
+
 /*
 ** The code in this file is only used if we are compiling multithreaded
 ** on a win32 system.
 */
 #ifdef SQLITE_MUTEX_W32
 
-/*
-** Include the header file for the Windows VFS.
-*/
-#include "os_win.h"
-
 /*
 ** Each recursive mutex is an instance of the following structure.
 */
diff --git a/tool/mkvsix.tcl b/tool/mkvsix.tcl
index 378435aab4..208ce2b142 100644
--- a/tool/mkvsix.tcl
+++ b/tool/mkvsix.tcl
@@ -66,14 +66,15 @@
 # containing the root of the source tree for SQLite.  The third argument is
 # optional and if present must contain the flavor the VSIX package to build.
 # Currently, the only supported package flavors are "WinRT", "WinRT81", "WP80",
-# and "Win32".  The fourth argument is optional and if present must be a string
-# containing a list of platforms to include in the VSIX package.  The platform
-# list is "platform1,platform2,platform3".  The fifth argument is optional and
-# if present must contain the version of Visual Studio required by the package.
-# Currently, the only supported versions are "2012" and "2013".  The package
-# flavor "WinRT81" is only supported when the Visual Studio version is "2013".
-# Typically, when on Windows, this script is executed using commands similar to
-# the following from a normal Windows command prompt:
+# "WP81", and "Win32".  The fourth argument is optional and if present must be
+# a string containing a list of platforms to include in the VSIX package.  The
+# platform list is "platform1,platform2,platform3".  The fifth argument is
+# optional and if present must contain the version of Visual Studio required by
+# the package.  Currently, the only supported versions are "2012" and "2013".
+# The package flavors "WinRT81" and "WP81" are only supported when the Visual
+# Studio version is "2013".  Typically, when on Windows, this script is
+# executed using commands similar to the following from a normal Windows
+# command prompt:
 #
 #                         CD /D C:\dev\sqlite\core
 #                         tclsh85 tool\mkvsix.tcl C:\Temp
@@ -210,6 +211,10 @@ proc getMaxPlatformVersionXmlChunk { packageFlavor vsVersion } {
       return [appendArgs \
           "\r\n    " {MaxPlatformVersion="8.0"}]
     }
+    WP81 {
+      return [appendArgs \
+          "\r\n    " {MaxPlatformVersion="8.1"}]
+    }
     default {
       return ""
     }
@@ -219,7 +224,8 @@ proc getMaxPlatformVersionXmlChunk { packageFlavor vsVersion } {
 proc getExtraFileListXmlChunk { packageFlavor vsVersion } {
   #
   # NOTE: Windows Phone 8.0 does not require any extra attributes in its VSIX
-  #       package SDK manifests.
+  #       package SDK manifests; however, it appears that Windows Phone 8.1
+  #       does.
   #
   if {[string equal $packageFlavor WP80]} then {
     return ""
@@ -359,6 +365,7 @@ set shortNames(WinRT,2013) SQLite.WinRT.2013
 set shortNames(WinRT81,2013) SQLite.WinRT81
 set shortNames(WP80,2012) SQLite.WP80
 set shortNames(WP80,2013) SQLite.WP80.2013
+set shortNames(WP81,2013) SQLite.WP81
 set shortNames(Win32,2012) SQLite.Win32
 set shortNames(Win32,2013) SQLite.Win32.2013
 
@@ -367,6 +374,7 @@ set displayNames(WinRT,2013) "SQLite for Windows Runtime"
 set displayNames(WinRT81,2013) "SQLite for Windows Runtime (Windows 8.1)"
 set displayNames(WP80,2012) "SQLite for Windows Phone"
 set displayNames(WP80,2013) "SQLite for Windows Phone"
+set displayNames(WP81,2013) "SQLite for Windows Phone 8.1"
 set displayNames(Win32,2012) "SQLite for Windows"
 set displayNames(Win32,2013) "SQLite for Windows"
 
@@ -408,6 +416,22 @@ if {[string equal $packageFlavor WinRT]} then {
   set extraSdkPath "\\..\\$targetPlatformIdentifier"
   set extraFileListAttributes \
       [getExtraFileListXmlChunk $packageFlavor $vsVersion]
+} elseif {[string equal $packageFlavor WP81]} then {
+  if {$vsVersion ne "2013"} then {
+    fail [appendArgs \
+        "unsupported combination, package flavor " $packageFlavor \
+        " is only supported with Visual Studio 2013"]
+  }
+  set shortName $shortNames($packageFlavor,$vsVersion)
+  set displayName $displayNames($packageFlavor,$vsVersion)
+  set targetPlatformIdentifier WindowsPhoneApp
+  set targetPlatformVersion v8.1
+  set minVsVersion [getMinVsVersionXmlChunk $vsVersion]
+  set maxPlatformVersion \
+      [getMaxPlatformVersionXmlChunk $packageFlavor $vsVersion]
+  set extraSdkPath "\\..\\$targetPlatformIdentifier"
+  set extraFileListAttributes \
+      [getExtraFileListXmlChunk $packageFlavor $vsVersion]
 } elseif {[string equal $packageFlavor Win32]} then {
   set shortName $shortNames($packageFlavor,$vsVersion)
   set displayName $displayNames($packageFlavor,$vsVersion)
@@ -422,7 +446,7 @@ if {[string equal $packageFlavor WinRT]} then {
 } else {
   fail [appendArgs \
       "unsupported package flavor, must be one of: " \
-      [list WinRT WinRT81 WP80 Win32]]
+      [list WinRT WinRT81 WP80 WP81 Win32]]
 }
 
 ###############################################################################