diff --git a/icu4c/source/aclocal.m4 b/icu4c/source/aclocal.m4
index ac462b3368d..69e82218c3f 100644
--- a/icu4c/source/aclocal.m4
+++ b/icu4c/source/aclocal.m4
@@ -339,30 +339,4 @@ AC_DEFUN(AC_CHECK_STRICT_COMPILE,
     fi
 ])
 
-dnl Define a sizeof checking macro that is a bit better than autoconf's
-dnl builtin (and heavily based on it, of course). The new macro is
-dnl AC_DO_CHECK_SIZEOF(TYPE [, CROSS_SIZE [, INCLUDES])
-AC_DEFUN(AC_DO_CHECK_SIZEOF,
-[changequote(<<, >>)dnl
-dnl The name to #define.
-define(<<AC_TYPE_NAME>>, translit(sizeof_$1, [a-z *], [A-Z_P]))dnl
-dnl The cache variable name.
-define(<<AC_CV_NAME>>, translit(ac_cv_sizeof_$1, [ *], [_p]))dnl
-changequote([, ])dnl
-AC_MSG_CHECKING(size of $1)
-AC_CACHE_VAL(AC_CV_NAME,
-[AC_TRY_RUN($3
-[#include <stdio.h>
-main()
-{
-  FILE *f=fopen("conftestval", "w");
-  if (!f) exit(1);
-  fprintf(f, "%d\n", (int)sizeof($1));
-  exit(0);
-}], AC_CV_NAME=`cat conftestval`, AC_CV_NAME=0, ifelse([$2], , , AC_CV_NAME=$2))])dnl
-AC_MSG_RESULT($AC_CV_NAME)
-AC_DEFINE_UNQUOTED(AC_TYPE_NAME, $AC_CV_NAME)
-undefine([AC_TYPE_NAME])dnl
-undefine([AC_CV_NAME])dnl
-])
 
diff --git a/icu4c/source/configure b/icu4c/source/configure
index b61e5e0c9b2..bab37e10585 100755
--- a/icu4c/source/configure
+++ b/icu4c/source/configure
@@ -7543,14 +7543,10 @@ fi
 
 
 
-ac_default_sizeof_wchar_t=4
-echo "$as_me:$LINENO: checking size of wchar_t" >&5
-echo $ECHO_N "checking size of wchar_t... $ECHO_C" >&6
-if test "${ac_cv_sizeof_wchar_t+set}" = set; then
+echo "$as_me:$LINENO: checking for wchar_t" >&5
+echo $ECHO_N "checking for wchar_t... $ECHO_C" >&6
+if test "${ac_cv_type_wchar_t+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
-else
-  if test "$cross_compiling" = yes; then
-  ac_cv_sizeof_wchar_t=$ac_default_sizeof_wchar_t
 else
   cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
@@ -7558,6 +7554,7 @@ _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
+
 #if STDC_HEADERS
 #include <stddef.h>
 #endif
@@ -7566,13 +7563,422 @@ cat >>conftest.$ac_ext <<_ACEOF
 #include <string.h>
 #include <wchar.h>
 #endif
-#include <stdio.h>
-main()
+
+int
+main ()
 {
-  FILE *f=fopen("conftestval", "w");
-  if (!f) exit(1);
-  fprintf(f, "%d\n", (int)sizeof(wchar_t));
-  exit(0);
+if ((wchar_t *) 0)
+  return 0;
+if (sizeof (wchar_t))
+  return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_type_wchar_t=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_type_wchar_t=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_type_wchar_t" >&5
+echo "${ECHO_T}$ac_cv_type_wchar_t" >&6
+
+echo "$as_me:$LINENO: checking size of wchar_t" >&5
+echo $ECHO_N "checking size of wchar_t... $ECHO_C" >&6
+if test "${ac_cv_sizeof_wchar_t+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test "$ac_cv_type_wchar_t" = yes; then
+  # The cast to unsigned long works around a bug in the HP C Compiler
+  # version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
+  # declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.
+  # This bug is HP SR number 8606223364.
+  if test "$cross_compiling" = yes; then
+  # Depending upon the size, compute the lo and hi bounds.
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+int
+main ()
+{
+static int test_array [1 - 2 * !(((long) (sizeof (wchar_t))) >= 0)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_lo=0 ac_mid=0
+  while :; do
+    cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+int
+main ()
+{
+static int test_array [1 - 2 * !(((long) (sizeof (wchar_t))) <= $ac_mid)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_hi=$ac_mid; break
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_lo=`expr $ac_mid + 1`
+		    if test $ac_lo -le $ac_mid; then
+		      ac_lo= ac_hi=
+		      break
+		    fi
+		    ac_mid=`expr 2 '*' $ac_mid + 1`
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+  done
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+int
+main ()
+{
+static int test_array [1 - 2 * !(((long) (sizeof (wchar_t))) < 0)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_hi=-1 ac_mid=-1
+  while :; do
+    cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+int
+main ()
+{
+static int test_array [1 - 2 * !(((long) (sizeof (wchar_t))) >= $ac_mid)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_lo=$ac_mid; break
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_hi=`expr '(' $ac_mid ')' - 1`
+		       if test $ac_mid -le $ac_hi; then
+			 ac_lo= ac_hi=
+			 break
+		       fi
+		       ac_mid=`expr 2 '*' $ac_mid`
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+  done
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_lo= ac_hi=
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+# Binary search between lo and hi bounds.
+while test "x$ac_lo" != "x$ac_hi"; do
+  ac_mid=`expr '(' $ac_hi - $ac_lo ')' / 2 + $ac_lo`
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+int
+main ()
+{
+static int test_array [1 - 2 * !(((long) (sizeof (wchar_t))) <= $ac_mid)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_hi=$ac_mid
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_lo=`expr '(' $ac_mid ')' + 1`
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+done
+case $ac_lo in
+?*) ac_cv_sizeof_wchar_t=$ac_lo;;
+'') { { echo "$as_me:$LINENO: error: cannot compute sizeof (wchar_t), 77
+See \`config.log' for more details." >&5
+echo "$as_me: error: cannot compute sizeof (wchar_t), 77
+See \`config.log' for more details." >&2;}
+   { (exit 1); exit 1; }; } ;;
+esac
+else
+  if test "$cross_compiling" = yes; then
+  { { echo "$as_me:$LINENO: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&5
+echo "$as_me: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&2;}
+   { (exit 1); exit 1; }; }
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if STDC_HEADERS
+#include <stddef.h>
+#endif
+#include <stdlib.h>
+#if HAVE_WCHAR_H
+#include <string.h>
+#include <wchar.h>
+#endif
+
+long longval () { return (long) (sizeof (wchar_t)); }
+unsigned long ulongval () { return (long) (sizeof (wchar_t)); }
+#include <stdio.h>
+#include <stdlib.h>
+int
+main ()
+{
+
+  FILE *f = fopen ("conftest.val", "w");
+  if (! f)
+    exit (1);
+  if (((long) (sizeof (wchar_t))) < 0)
+    {
+      long i = longval ();
+      if (i != ((long) (sizeof (wchar_t))))
+	exit (1);
+      fprintf (f, "%ld\n", i);
+    }
+  else
+    {
+      unsigned long i = ulongval ();
+      if (i != ((long) (sizeof (wchar_t))))
+	exit (1);
+      fprintf (f, "%lu\n", i);
+    }
+  exit (ferror (f) || fclose (f) != 0);
+
+  ;
+  return 0;
 }
 _ACEOF
 rm -f conftest$ac_exeext
@@ -7586,18 +7992,27 @@ if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
   ac_status=$?
   echo "$as_me:$LINENO: \$? = $ac_status" >&5
   (exit $ac_status); }; }; then
-  ac_cv_sizeof_wchar_t=`cat conftestval`
+  ac_cv_sizeof_wchar_t=`cat conftest.val`
 else
   echo "$as_me: program exited with status $ac_status" >&5
 echo "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
 ( exit $ac_status )
-ac_cv_sizeof_wchar_t=0
+{ { echo "$as_me:$LINENO: error: cannot compute sizeof (wchar_t), 77
+See \`config.log' for more details." >&5
+echo "$as_me: error: cannot compute sizeof (wchar_t), 77
+See \`config.log' for more details." >&2;}
+   { (exit 1); exit 1; }; }
 fi
 rm -f core *.core gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
 fi
 fi
+rm -f conftest.val
+else
+  ac_cv_sizeof_wchar_t=0
+fi
+fi
 echo "$as_me:$LINENO: result: $ac_cv_sizeof_wchar_t" >&5
 echo "${ECHO_T}$ac_cv_sizeof_wchar_t" >&6
 cat >>confdefs.h <<_ACEOF
@@ -7606,12 +8021,13 @@ _ACEOF
 
 
 U_SIZEOF_WCHAR_T=$ac_cv_sizeof_wchar_t
+# We do this check to verify that everything is okay.
 if test $U_SIZEOF_WCHAR_T = 0; then
-	if test $U_HAVE_WCHAR_H=1; then
-	   { { echo "$as_me:$LINENO: error: There is wchar.h but the size of wchar_t is 0" >&5
+    if test $U_HAVE_WCHAR_H=1; then
+       { { echo "$as_me:$LINENO: error: There is wchar.h but the size of wchar_t is 0" >&5
 echo "$as_me: error: There is wchar.h but the size of wchar_t is 0" >&2;}
    { (exit 1); exit 1; }; }
-	fi
+    fi
 fi
 
 
diff --git a/icu4c/source/configure.in b/icu4c/source/configure.in
index 291348cdf0e..a17af18bef9 100644
--- a/icu4c/source/configure.in
+++ b/icu4c/source/configure.in
@@ -791,8 +791,7 @@ fi
 AC_SUBST(U_HAVE_WCHAR_H)
 AC_SUBST(U_HAVE_WCSCPY)
 
-ac_default_sizeof_wchar_t=4
-AC_DO_CHECK_SIZEOF(wchar_t,$ac_default_sizeof_wchar_t,[
+AC_CHECK_SIZEOF([wchar_t], 0, [
 #if STDC_HEADERS
 #include <stddef.h>
 #endif
@@ -801,14 +800,12 @@ AC_DO_CHECK_SIZEOF(wchar_t,$ac_default_sizeof_wchar_t,[
 #include <string.h>
 #include <wchar.h>
 #endif])
-dnl We could set ac_cv_sizeof_wchar_t to the default if the check returned
-dnl 0 (unknown) but we'd rather do it in the headers, so we know we had no
-dnl clue at configure time.
 U_SIZEOF_WCHAR_T=$ac_cv_sizeof_wchar_t
+# We do this check to verify that everything is okay.
 if test $U_SIZEOF_WCHAR_T = 0; then
-	if test $U_HAVE_WCHAR_H=1; then
-	   AC_MSG_ERROR(There is wchar.h but the size of wchar_t is 0)
-	fi
+    if test $U_HAVE_WCHAR_H=1; then
+       AC_MSG_ERROR(There is wchar.h but the size of wchar_t is 0)
+    fi
 fi
 AC_SUBST(U_SIZEOF_WCHAR_T)