Index: build/ac-macros/sqlite.m4
===================================================================
--- build/ac-macros/sqlite.m4	(revision 27973)
+++ build/ac-macros/sqlite.m4	(working copy)
@@ -52,6 +52,8 @@
           svn_lib_sqlite="yes"
           SVN_SQLITE_INCLUDES="`$pkg_config $SQLITE_PKGNAME --cflags`"
           SVN_SQLITE_LIBS="`$pkg_config $SQLITE_PKGNAME --libs`"
+          AC_CHECK_LIB(sqlite3, sqlite3_threadsafe,
+                       [threadsafety_runtime_check_avail=yes])
           ;;
         *)
           AC_MSG_RESULT([none or unsupported $sqlite_version])
@@ -68,6 +70,11 @@
     fi
   ])
 
+  if test "$threadsafety_runtime_check_avail" = "yes"; then
+    AC_DEFINE([SVN_HAVE_SQLITE_THREADSAFE_PREDICATE], [1],
+      [Defined if SQLite 3.5+'s thread-safety runtime check is available.])
+  fi
+
   AC_SUBST(SVN_SQLITE_INCLUDES)
   AC_SUBST(SVN_SQLITE_LIBS)
 ])
@@ -94,8 +101,12 @@
         else
           SVN_SQLITE_LIBS="-lsqlite3"
         fi
-      ]) ])
 
+        AC_CHECK_LIB(sqlite3, sqlite3_threadsafe,
+                     [threadsafety_runtime_check_avail=yes])
+      ])
+    ])
+
   if test "$sqlite_dir" != "" && test -d "$sqlite_dir"; then
     CPPFLAGS="$save_CPPFLAGS"
     LDFLAGS="$save_LDFLAGS"
Index: subversion/libsvn_fs_util/sqlite-util.c
===================================================================
--- subversion/libsvn_fs_util/sqlite-util.c	(revision 27973)
+++ subversion/libsvn_fs_util/sqlite-util.c	(working copy)
@@ -23,9 +23,11 @@
 
 #include <apr_general.h>
 #include <apr_pools.h>
+#include <apr_dso.h>
 
 #include <sqlite3.h>
 
+#include "svn_types.h"
 #include "svn_fs.h"
 #include "svn_path.h"
 #include "svn_mergeinfo.h"
@@ -189,11 +191,66 @@
     return svn_fs__sqlite_stmt_error(stmt);
 }
 
+#ifndef SVN_HAVE_SQLITE_THREADSAFE_PREDICATE
+#include <dlfcn.h>
+#endif
+
+/* If possible, verify that SQLite was compiled in a thread-safe
+   manner.  The library will be unloaded when POOL is destroyed. */
+static svn_error_t *
+init_sqlite(apr_pool_t *pool)
+{
+  svn_boolean_t is_threadsafe = TRUE;
+
+  /* SQLite 3.5 allows verification of its thread-safety at runtime.
+     Older versions are simply expected to have been configured with
+     --enable-threadsafe, which compiles with -DSQLITE_THREADSAFE=1
+     (or -DTHREADSAFE, for older versions). */
+#ifdef SVN_HAVE_SQLITE_THREADSAFE_PREDICATE
+  /* sqlite3_threadsafe() was available at Subversion 'configure'-time. */
+  is_threadsafe = sqlite3_threadsafe();
+
+#elsif APR_HAS_DSO
+  /* Attempt to dynamically load sqlite3_threadsafe(), since the
+     version of SQLite present at compile-time may've changed. */
+  apr_status_t status;
+  apr_dso_handle_t *dso = NULL;
+  apr_dso_handle_sym_t symbol;
+
+#if DARWIN
+  status = apr_dso_load(&dso, "libsqlite3.dylib", pool);
+#endif
+  if (dso == NULL)
+    status = apr_dso_load(&dso, "libsqlite3.so", pool);
+
+  if (dso)
+    {
+      status = apr_dso_sym(&symbol, dso, "sqlite3_threadsafe");
+      if (symbol && !status)
+        {
+          int (*threadsafe_func)(void) = symbol;
+          is_threadsafe = (*threadsafe_func)();
+        }
+    }
+#endif  /* SVN_HAVE_SQLITE_THREADSAFE_PREDICATE */
+
+  if (! is_threadsafe)
+    return svn_error_create(SVN_ERR_FS_SQLITE_ERROR, NULL,
+                            _("SQLite is required to be compiled and run in "
+                              "thread-safe mode"));
+  return SVN_NO_ERROR;
+}
+
 svn_error_t *
 svn_fs__sqlite_open(sqlite3 **db, const char *repos_path, apr_pool_t *pool)
 {
-  const char *db_path = svn_path_join(repos_path,
-                                      SVN_FS__SQLITE_DB_NAME, pool);
+  const char *db_path;
+
+  SVN_ERR(init_sqlite(pool));
+
+  db_path = svn_path_join(repos_path, SVN_FS__SQLITE_DB_NAME, pool);
+
+  /* Open the database. */
   SVN_FS__SQLITE_ERR(sqlite3_open(db_path, db), *db);
   /* Retry until timeout when database is busy. */
   SVN_FS__SQLITE_ERR(sqlite3_busy_timeout(*db, BUSY_TIMEOUT), *db);