diff --git a/icu4c/source/configure b/icu4c/source/configure
index 9c4c84ff005..b73e1e63b43 100755
--- a/icu4c/source/configure
+++ b/icu4c/source/configure
@@ -721,6 +721,8 @@ INSTALL_DATA
 INSTALL_SCRIPT
 INSTALL_PROGRAM
 CPP
+OTHER_ICUUC_LIBS
+OTHER_ICUUC_CFLAGS
 ICULEHB_LIBS
 ICULEHB_CFLAGS
 PKG_CONFIG_LIBDIR
@@ -771,7 +773,6 @@ infodir
 docdir
 oldincludedir
 includedir
-runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -838,6 +839,8 @@ PKG_CONFIG_PATH
 PKG_CONFIG_LIBDIR
 ICULEHB_CFLAGS
 ICULEHB_LIBS
+OTHER_ICUUC_CFLAGS
+OTHER_ICUUC_LIBS
 CPP'
 
 
@@ -877,7 +880,6 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
-runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1128,15 +1130,6 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
-  -runstatedir | --runstatedir | --runstatedi | --runstated \
-  | --runstate | --runstat | --runsta | --runst | --runs \
-  | --run | --ru | --r)
-    ac_prev=runstatedir ;;
-  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
-  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
-  | --run=* | --ru=* | --r=*)
-    runstatedir=$ac_optarg ;;
-
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1274,7 +1267,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir runstatedir
+		libdir localedir mandir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1427,7 +1420,6 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
-  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -1522,6 +1514,10 @@ Some influential environment variables:
               C compiler flags for ICULEHB, overriding pkg-config
   ICULEHB_LIBS
               linker flags for ICULEHB, overriding pkg-config
+  OTHER_ICUUC_CFLAGS
+              C compiler flags for OTHER_ICUUC, overriding pkg-config
+  OTHER_ICUUC_LIBS
+              linker flags for OTHER_ICUUC, overriding pkg-config
   CPP         C preprocessor
 
 Use these variables to override the choices made by 'configure' or to help
@@ -4685,6 +4681,78 @@ else
 printf "%s\n" "yes" >&6; }
         have_icu_le_hb=true
 fi
+# is there another ICUUC installed? For layoutex.
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for OTHER_ICUUC" >&5
+$as_echo_n "checking for OTHER_ICUUC... " >&6; }
+
+if test -n "$OTHER_ICUUC_CFLAGS"; then
+    pkg_cv_OTHER_ICUUC_CFLAGS="$OTHER_ICUUC_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"icu-uc\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "icu-uc") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_OTHER_ICUUC_CFLAGS=`$PKG_CONFIG --cflags "icu-uc" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$OTHER_ICUUC_LIBS"; then
+    pkg_cv_OTHER_ICUUC_LIBS="$OTHER_ICUUC_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"icu-uc\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "icu-uc") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_OTHER_ICUUC_LIBS=`$PKG_CONFIG --libs "icu-uc" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+   	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        OTHER_ICUUC_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "icu-uc" 2>&1`
+        else
+	        OTHER_ICUUC_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "icu-uc" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$OTHER_ICUUC_PKG_ERRORS" >&5
+
+	:
+elif test $pkg_failed = untried; then
+     	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+	:
+else
+	OTHER_ICUUC_CFLAGS=$pkg_cv_OTHER_ICUUC_CFLAGS
+	OTHER_ICUUC_LIBS=$pkg_cv_OTHER_ICUUC_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+	have_other_icu_uc=true
+fi
 
 # Ensure that if CXXFLAGS/CFLAGS were not set when calling configure, set it correctly based on (enable/disable) debug or release option
 # The release mode use is the default one for autoconf
diff --git a/icu4c/source/configure.ac b/icu4c/source/configure.ac
index da4f170abfa..cce3adbc8fc 100644
--- a/icu4c/source/configure.ac
+++ b/icu4c/source/configure.ac
@@ -143,6 +143,8 @@ AC_MSG_NOTICE([versions of the compilers used:])
 # pkg-config is needed for harfbuzz support
 PKG_PROG_PKG_CONFIG([0.20])
 PKG_CHECK_MODULES(ICULEHB, icu-le-hb, have_icu_le_hb=true, :)
+# is there another ICUUC installed? For layoutex.
+PKG_CHECK_MODULES(OTHER_ICUUC, icu-uc, have_other_icu_uc=true, :)
 
 # Ensure that if CXXFLAGS/CFLAGS were not set when calling configure, set it correctly based on (enable/disable) debug or release option
 # The release mode use is the default one for autoconf
@@ -638,7 +640,7 @@ sparc-*-solaris*)
 ia64-*-hpux*)
 # There has been some issues with building ICU data on HPUX ia64 aCC
 # when using the assemble code setting below.  For now, build without
-# assemble code for this platform.  This will increase the build time.   
+# assemble code for this platform.  This will increase the build time.
 #    GENCCODE_ASSEMBLY="-a aCC-ia64"
     ;;
 esac
diff --git a/icu4c/source/icudefs.mk.in b/icu4c/source/icudefs.mk.in
index 251e020903e..fc96a865883 100644
--- a/icu4c/source/icudefs.mk.in
+++ b/icu4c/source/icudefs.mk.in
@@ -50,13 +50,13 @@ SO_TARGET_VERSION_MAJOR = @LIB_VERSION_MAJOR@
 # The ICU data external name is usually icudata; the entry point name is
 # the version-dependent name (for no particular reason except it was easier
 # to change the build this way). When building in common mode, the data
-# name is the versioned platform-dependent one. 
+# name is the versioned platform-dependent one.
 
 ICUDATA_DIR = @pkgicudatadir@/$(PACKAGE)$(ICULIBSUFFIX)/$(VERSION)
 
 ICUDATA_BASENAME_VERSION = $(ICUPREFIX)dt@LIB_VERSION_MAJOR@
-# the entry point is almost like the basename, but has the lib suffix.  
-ICUDATA_ENTRY_POINT = $(ICUPREFIX)dt@ICULIBSUFFIXCNAME@@LIB_VERSION_MAJOR@ 
+# the entry point is almost like the basename, but has the lib suffix.
+ICUDATA_ENTRY_POINT = $(ICUPREFIX)dt@ICULIBSUFFIXCNAME@@LIB_VERSION_MAJOR@
 ICUDATA_CHAR = @ICUDATA_CHAR@
 ICUDATA_PLATFORM_NAME = $(ICUDATA_BASENAME_VERSION)$(ICUDATA_CHAR)
 PKGDATA_LIBSTATICNAME = -L $(STATIC_PREFIX)$(ICUPREFIX)$(DATA_STUBNAME)$(ICULIBSUFFIX)
@@ -210,7 +210,7 @@ LIBICU = $(LIBPREFIX)$(ICUPREFIX)
 ifneq ($(ENABLE_SHARED),YES)
 STATIC_PREFIX_WHEN_USED = s
 else
-STATIC_PREFIX_WHEN_USED = 
+STATIC_PREFIX_WHEN_USED =
 endif
 
 # Static library prefix and file extension
@@ -268,6 +268,18 @@ ICULEHB_TRUE=#
 ICULEHB_FALSE=
 endif
 
+OTHER_ICUUC_CFLAGS=@OTHER_ICUUC_CFLAGS@
+OTHER_ICUUC_LIBS=@OTHER_ICUUC_LIBS@
+ifneq ($(OTHER_ICUUC_CFLAGS),)
+HAVE_OTHER_ICUUC=yes
+OTHERICUUC_TRUE=
+OTHERICUUC_FALSE=#
+else
+HAVE_OTHER_ICUUC=no
+OTHERICUUC_TRUE=#
+OTHERICUUC_FALSE=
+endif
+
 # Just the libs.
 ICULIBS_DT	= -l$(STATIC_PREFIX_WHEN_USED)$(ICUPREFIX)$(DATA_STUBNAME)$(ICULIBSUFFIX)$(SO_TARGET_VERSION_SUFFIX)
 ICULIBS_UC	= -l$(STATIC_PREFIX_WHEN_USED)$(ICUPREFIX)$(COMMON_STUBNAME)$(ICULIBSUFFIX)$(SO_TARGET_VERSION_SUFFIX)
diff --git a/icu4c/source/layoutex/Makefile.in b/icu4c/source/layoutex/Makefile.in
index 1826b568ae8..ba19b1d521e 100644
--- a/icu4c/source/layoutex/Makefile.in
+++ b/icu4c/source/layoutex/Makefile.in
@@ -56,16 +56,29 @@ CXXFLAGS += $(LIBCXXFLAGS)
 
 
 ifeq ($(USING_ICULEHB),no)
-# cppflags: load .. so that #include <layout/...> works
-ICULE_CFLAGS=-I$(srcdir)/..
+error("ICULEHB is required, see build instructions")
 else
 ICULE_CFLAGS=$(ICULEHB_CFLAGS)
 endif
 
-CPPFLAGS += -I$(srcdir) -I$(srcdir)/unicode -I$(top_srcdir)/common $(ICULE_CFLAGS) $(LIBCPPFLAGS)
+CPPFLAGS += -I$(srcdir)
+
+ifeq ($(HAVE_OTHER_ICUUC),yes)
+# use other installed ICU
+CPPFLAGS += $(OTHER_ICUUC_CFLAGS) -ULE_USE_CMEMORY
+LIBS += $(OTHER_ICUUC_LIBS)
+DEFS += -DHAVE_OTHER_ICUUC
+# Do not set U_LAYOUTEX_IMPLEMENTATION
+else
+# attempt to use 'this' ICU
+CPPFLAGS += -I$(srcdir)/unicode -I$(top_srcdir)/common $(ICULE_CFLAGS)
 DEFS += -DU_LAYOUTEX_IMPLEMENTATION
+LIBS += $(LIBICUUC) $(DEFAULT_LIBS)
+endif
+
+CPPFLAGS += $(LIBCPPFLAGS) $(ICULE_CFLAGS)
 LDFLAGS += $(LDFLAGSICULX)
-LIBS = $(LIBICUUC) $(LIBICULE) $(DEFAULT_LIBS)
+LIBS += $(ICULEHB_LIBS)
 
 SOURCES = $(shell cat $(srcdir)/sources.txt)
 OBJECTS = $(SOURCES:.cpp=.o)
diff --git a/icu4c/source/layoutex/ParagraphLayout.cpp b/icu4c/source/layoutex/ParagraphLayout.cpp
index 6ac0c7d49eb..71603830d5b 100644
--- a/icu4c/source/layoutex/ParagraphLayout.cpp
+++ b/icu4c/source/layoutex/ParagraphLayout.cpp
@@ -30,6 +30,14 @@
 
 U_NAMESPACE_BEGIN
 
+#ifndef FALSE
+#define FALSE false
+#endif
+
+#ifndef TRUE
+#define TRUE true
+#endif
+
 #define ARRAY_SIZE(array) (sizeof array  / sizeof array[0])
 
 /* Leave this copyright notice here! It needs to go somewhere in this library. */
diff --git a/icu4c/source/layoutex/RunArrays.cpp b/icu4c/source/layoutex/RunArrays.cpp
index 09692dc57ac..8f8902c196b 100644
--- a/icu4c/source/layoutex/RunArrays.cpp
+++ b/icu4c/source/layoutex/RunArrays.cpp
@@ -16,6 +16,15 @@
 
 U_NAMESPACE_BEGIN
 
+#ifndef FALSE
+#define FALSE false
+#endif
+
+#ifndef TRUE
+#define TRUE true
+#endif
+
+
 const char RunArray::fgClassID = 0;
 
 RunArray::RunArray(le_int32 initialCapacity)
diff --git a/icu4c/source/layoutex/cmemory.h b/icu4c/source/layoutex/cmemory.h
new file mode 120000
index 00000000000..353cbff04b0
--- /dev/null
+++ b/icu4c/source/layoutex/cmemory.h
@@ -0,0 +1 @@
+../common/cmemory.h
\ No newline at end of file
diff --git a/icu4c/source/layoutex/cstring.h b/icu4c/source/layoutex/cstring.h
new file mode 120000
index 00000000000..6ba096f8f6c
--- /dev/null
+++ b/icu4c/source/layoutex/cstring.h
@@ -0,0 +1 @@
+../common/cstring.h
\ No newline at end of file
diff --git a/icu4c/source/layoutex/uassert.h b/icu4c/source/layoutex/uassert.h
new file mode 120000
index 00000000000..ae094c34539
--- /dev/null
+++ b/icu4c/source/layoutex/uassert.h
@@ -0,0 +1 @@
+../common/uassert.h
\ No newline at end of file
diff --git a/icu4c/source/layoutex/usc_impl.h b/icu4c/source/layoutex/usc_impl.h
new file mode 120000
index 00000000000..336a38c8849
--- /dev/null
+++ b/icu4c/source/layoutex/usc_impl.h
@@ -0,0 +1 @@
+../common/usc_impl.h
\ No newline at end of file