Index: generic/tcl.decls
==================================================================
--- generic/tcl.decls
+++ generic/tcl.decls
@@ -2388,14 +2388,22 @@
 }
 declare 694 {
     int Tcl_ListObjRange(Tcl_Interp *interp, Tcl_Obj *objPtr,
 	    Tcl_Size start, Tcl_Size end, Tcl_Obj **resultPtrPtr)
 }
+
+# TIP 726
+declare 695 {
+    const char *Tcl_UtfToNormalizedDString(Tcl_Interp *interp,
+	    const char *bytes, Tcl_Size length,
+	    Tcl_UnicodeNormalizationForm normForm, int profile,
+	    Tcl_DString *dsPtr)
+}
 
 # ----- BASELINE -- FOR -- 9.1.0 ----- #
 
-declare 695 {
+declare 696 {
     void TclUnusedStubEntry(void)
 }
 
 ##############################################################################
 

Index: generic/tcl.h
==================================================================
--- generic/tcl.h
+++ generic/tcl.h
@@ -2044,10 +2044,17 @@
 #elif TCL_UTF_MAX == 3 && !defined(BUILD_tcl)
 typedef unsigned short Tcl_UniChar;
 #else
 #   error "This TCL_UTF_MAX value is not supported"
 #endif
+
+/*
+ * Specifiers for Unicode normalization forms.
+ */
+typedef enum {
+    TCL_NFC, TCL_NFD, TCL_NFKC, TCL_NFKD
+} Tcl_UnicodeNormalizationForm;
 
 /*
  *----------------------------------------------------------------------------
  * TIP #59: The following structure is used in calls 'Tcl_RegisterConfig' to
  * provide the system with the embedded configuration data.

Index: generic/tclDecls.h
==================================================================
--- generic/tclDecls.h
+++ generic/tclDecls.h
@@ -1885,10 +1885,15 @@
 /* 694 */
 EXTERN int		Tcl_ListObjRange(Tcl_Interp *interp, Tcl_Obj *objPtr,
 				Tcl_Size start, Tcl_Size end,
 				Tcl_Obj **resultPtrPtr);
 /* 695 */
+EXTERN const char *	Tcl_UtfToNormalizedDString(Tcl_Interp *interp,
+				const char *bytes, Tcl_Size length,
+				Tcl_UnicodeNormalizationForm normForm,
+				int profile, Tcl_DString *dsPtr);
+/* 696 */
 EXTERN void		TclUnusedStubEntry(void);
 
 typedef struct {
     const struct TclPlatStubs *tclPlatStubs;
     const struct TclIntStubs *tclIntStubs;
@@ -2592,11 +2597,12 @@
     int (*tcl_IsEmpty) (Tcl_Obj *obj); /* 690 */
     const char * (*tcl_GetEncodingNameForUser) (Tcl_DString *bufPtr); /* 691 */
     int (*tcl_ListObjReverse) (Tcl_Interp *interp, Tcl_Obj *objPtr, Tcl_Obj **resultPtrPtr); /* 692 */
     int (*tcl_ListObjRepeat) (Tcl_Interp *interp, Tcl_Size repeatCount, Tcl_Size objc, Tcl_Obj *const objv[], Tcl_Obj **resultPtrPtr); /* 693 */
     int (*tcl_ListObjRange) (Tcl_Interp *interp, Tcl_Obj *objPtr, Tcl_Size start, Tcl_Size end, Tcl_Obj **resultPtrPtr); /* 694 */
-    void (*tclUnusedStubEntry) (void); /* 695 */
+    const char * (*tcl_UtfToNormalizedDString) (Tcl_Interp *interp, const char *bytes, Tcl_Size length, Tcl_UnicodeNormalizationForm normForm, int profile, Tcl_DString *dsPtr); /* 695 */
+    void (*tclUnusedStubEntry) (void); /* 696 */
 } TclStubs;
 
 extern const TclStubs *tclStubsPtr;
 
 #ifdef __cplusplus
@@ -3932,12 +3938,14 @@
 	(tclStubsPtr->tcl_ListObjReverse) /* 692 */
 #define Tcl_ListObjRepeat \
 	(tclStubsPtr->tcl_ListObjRepeat) /* 693 */
 #define Tcl_ListObjRange \
 	(tclStubsPtr->tcl_ListObjRange) /* 694 */
+#define Tcl_UtfToNormalizedDString \
+	(tclStubsPtr->tcl_UtfToNormalizedDString) /* 695 */
 #define TclUnusedStubEntry \
-	(tclStubsPtr->tclUnusedStubEntry) /* 695 */
+	(tclStubsPtr->tclUnusedStubEntry) /* 696 */
 
 #endif /* defined(USE_TCL_STUBS) */
 
 /* !END!: Do not edit above this line. */
 

Index: generic/tclEncoding.c
==================================================================
--- generic/tclEncoding.c
+++ generic/tclEncoding.c
@@ -9,10 +9,11 @@
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  */
 
 #include "tclInt.h"
 #include <assert.h>
+#include "../utf8proc/utf8proc.h" /* Relative path to ignore system include */
 
 typedef size_t (LengthProc)(const char *src);
 
 /*
  * The following data structure represents an encoding, which describes how to
@@ -4635,12 +4636,96 @@
 		Tcl_NewStringObj(encodingProfiles[i].name, TCL_INDEX_NONE));
     }
     Tcl_SetObjResult(interp, objPtr);
 }
 
+/*
+ * Tcl_UtfToNormalizedDString --
+ *
+ *	Converts the passed string to a Unicode normalization form storing
+ *	it in dsPtr.
+ *
+ * Results:
+ *	Pointer to content of dsPtr on success, and NULL on error.
+ *
+ */
+const char *
+Tcl_UtfToNormalizedDString(
+    Tcl_Interp *interp, /* Used for error messages. May be NULL */
+    const char *bytes,  /* Operand encoded in Tcl internal UTF8 */
+    Tcl_Size length,	/* Length bytes[], or -1 if NUL terminated */
+    Tcl_UnicodeNormalizationForm normForm, /* TCL_{NFC,NFD,NFKC,NFKC} */
+    int profile,        /* TCL_ENCODING_PROFILE_{STRICT,REPLACE} */
+    Tcl_DString *dsPtr) /* Converted output string in Tcl internal
+			   UTF8 encoding. Init'ed by function */
+{
+    Tcl_DStringInit(dsPtr);
+
+    if (profile != TCL_ENCODING_PROFILE_REPLACE &&
+	profile != TCL_ENCODING_PROFILE_STRICT) {
+	Tcl_SetObjResult(interp,
+	    Tcl_ObjPrintf("Invalid value %d passed for encoding profile",
+		profile));
+    }
+
+    Tcl_Encoding encoding = Tcl_GetEncoding(interp, "utf-8");
+    if (encoding == NULL) {
+	return NULL;
+    }
+
+    int result;
+    Tcl_DString dsExt;
+    result = Tcl_UtfToExternalDStringEx(interp, encoding, bytes, length,
+	profile, &dsExt, NULL);
+    /* !!! dsExt needs to be freed even in case of error returns */
+
+    if (result == TCL_OK) {
+	utf8proc_uint8_t *normUtf8;
+        utf8proc_ssize_t normLength;
+	Tcl_Size dsLength = Tcl_DStringLength(&dsExt);
+	const utf8proc_uint8_t *dsStr =
+	    (utf8proc_uint8_t *)Tcl_DStringValue(&dsExt);
+        utf8proc_option_t options = UTF8PROC_STABLE;
+        switch (normForm) {
+        case TCL_NFC:
+            options |= UTF8PROC_COMPOSE;
+            break;
+        case TCL_NFD:
+            options |= UTF8PROC_DECOMPOSE;
+            break;
+        case TCL_NFKC:
+            options |= UTF8PROC_COMPOSE|UTF8PROC_COMPAT;
+            break;
+        case TCL_NFKD:
+            options |= UTF8PROC_DECOMPOSE|UTF8PROC_COMPAT;
+            break;
+        }
+	normLength = utf8proc_map_custom(dsStr, dsLength, &normUtf8,
+	    options, NULL, NULL);
+
+	if (normLength < 0) {
+            const char *errorMsg = utf8proc_errmsg(normLength);
+            Tcl_SetObjResult(
+                interp, Tcl_NewStringObj(
+                    errorMsg ? errorMsg : "Unicode normalization failed.", -1));
+            result = TCL_ERROR;
+        } else {
+            /* Convert standard UTF8 to internal UTF8 */
+            assert(normUtf8);
+            result = Tcl_ExternalToUtfDStringEx(interp, encoding,
+                (const char *)normUtf8, normLength, profile, dsPtr, NULL);
+            free(normUtf8);
+        }
+    }
+
+    Tcl_DStringFree(&dsExt);
+    Tcl_FreeEncoding(encoding);
+    return result == TCL_OK ? Tcl_DStringValue(dsPtr) : NULL;
+}
+
 /*
  * Local Variables:
  * mode: c
  * c-basic-offset: 4
  * fill-column: 78
  * End:
  */

Index: generic/tclStubInit.c
==================================================================
--- generic/tclStubInit.c
+++ generic/tclStubInit.c
@@ -1500,9 +1500,10 @@
     Tcl_IsEmpty, /* 690 */
     Tcl_GetEncodingNameForUser, /* 691 */
     Tcl_ListObjReverse, /* 692 */
     Tcl_ListObjRepeat, /* 693 */
     Tcl_ListObjRange, /* 694 */
-    TclUnusedStubEntry, /* 695 */
+    Tcl_UtfToNormalizedDString, /* 695 */
+    TclUnusedStubEntry, /* 696 */
 };
 
 /* !END!: Do not edit above this line. */

Index: unix/Makefile.in
==================================================================
--- unix/Makefile.in
+++ unix/Makefile.in
@@ -239,10 +239,11 @@
 
 ZLIB_DIR		= ${COMPAT_DIR}/zlib
 ZLIB_INCLUDE		= @ZLIB_INCLUDE@
 TOMMATH_DIR		= $(TOP_DIR)/libtommath
 TOMMATH_INCLUDE		= @TOMMATH_INCLUDE@
+UTF8PROC_DIR		= $(TOP_DIR)/utf8proc
 
 CC			= @CC@
 OBJEXT			= @OBJEXT@
 
 #CC			= purify -best-effort @CC@ -DPURIFY
@@ -345,10 +346,12 @@
 	bn_mp_signed_rsh.o \
 	bn_mp_to_ubin.o bn_mp_unpack.o \
 	bn_s_mp_toom_mul.o bn_s_mp_toom_sqr.o bn_mp_to_radix.o \
 	bn_mp_ubin_size.o bn_mp_xor.o bn_mp_zero.o bn_s_mp_add.o \
 	bn_s_mp_mul_digs.o bn_s_mp_sqr.o bn_s_mp_sub.o
+
+UTF8PROC_OBJS = utf8proc.o
 
 STUB_LIB_OBJS = tclStubLib.o \
 	tclStubCall.o \
 	tclStubLibTbl.o \
 	tclTomMathStubLib.o \
@@ -372,11 +375,11 @@
 	Zinffast.o Zinflate.o Zinftrees.o Ztrees.o Zuncompr.o Zzutil.o
 
 TCL_OBJS = ${GENERIC_OBJS} ${UNIX_OBJS} ${NOTIFY_OBJS} ${COMPAT_OBJS} \
 	${OO_OBJS} @DL_OBJS@ @PLAT_OBJS@
 
-OBJS = ${TCL_OBJS} @DTRACE_OBJ@ @ZLIB_OBJS@ @TOMMATH_OBJS@
+OBJS = ${TCL_OBJS} ${UTF8PROC_OBJS} @DTRACE_OBJ@ @ZLIB_OBJS@ @TOMMATH_OBJS@
 
 TCL_DECLS = \
 	$(GENERIC_DIR)/tcl.decls \
 	$(GENERIC_DIR)/tclInt.decls \
 	$(GENERIC_DIR)/tclOO.decls \
@@ -718,16 +721,20 @@
 	$(ZLIB_DIR)/inftrees.c \
 	$(ZLIB_DIR)/trees.c \
 	$(ZLIB_DIR)/uncompr.c \
 	$(ZLIB_DIR)/zutil.c
 
+UTF8PROC_SRCS = \
+	$(UTF8PROC_DIR)/utf8proc.c
+
 # Note: don't include DL_SRCS or MAC_OSX_SRCS in SRCS: most of those files
 # won't compile on the current machine, and they will cause problems for
 # things like "make depend".
 
 SRCS = $(GENERIC_SRCS) $(UNIX_SRCS) $(NOTIFY_SRCS) \
-	$(OO_SRCS) $(STUB_SRCS) @PLAT_SRCS@ @ZLIB_SRCS@ @TOMMATH_SRCS@
+	$(OO_SRCS) $(UTF8PROC_SRCS) $(STUB_SRCS) \
+	@PLAT_SRCS@ @ZLIB_SRCS@ @TOMMATH_SRCS@
 
 ###
 # Tip 430 - ZipFS Modifications
 ###
 
@@ -1869,10 +1876,13 @@
 	$(CC) -c $(CC_SWITCHES) $(TCL_LOCATIONS) $(UNIX_DIR)/tclUnixInit.c
 
 tclUnixCompat.o: $(UNIX_DIR)/tclUnixCompat.c
 	$(CC) -c $(CC_SWITCHES) $(UNIX_DIR)/tclUnixCompat.c
 
+utf8proc.o: $(UTF8PROC_DIR)/utf8proc.c
+	$(CC) -c $(CC_SWITCHES) $(UTF8PROC_DIR)/utf8proc.c
+
 # The following are Mac OS X only sources:
 tclMacOSXBundle.o: $(MAC_OSX_DIR)/tclMacOSXBundle.c
 	$(CC) -c $(CC_SWITCHES) $(MAC_OSX_DIR)/tclMacOSXBundle.c
 
 tclMacOSXFCmd.o: $(MAC_OSX_DIR)/tclMacOSXFCmd.c
@@ -1885,11 +1895,11 @@
 tclWinError.o: $(TOP_DIR)/win/tclWinError.c
 	$(CC) -c $(CC_SWITCHES) $(TOP_DIR)/win/tclWinError.c
 
 # DTrace support
 
-$(TCL_OBJS) $(STUB_LIB_OBJS) $(TCLSH_OBJS) $(TCLTEST_OBJS) $(XTTEST_OBJS) $(TOMMATH_OBJS): @DTRACE_HDR@
+$(TCL_OBJS) $(STUB_LIB_OBJS) $(TCLSH_OBJS) $(TCLTEST_OBJS) $(XTTEST_OBJS) $(TOMMATH_OBJS) $(UTF8PROC_OBJS): @DTRACE_HDR@
 
 $(DTRACE_HDR): $(DTRACE_SRC)
 	$(DTRACE) -h $(DTRACE_SWITCHES) -o $@ -s $(DTRACE_SRC)
 
 $(DTRACE_OBJ): $(DTRACE_SRC) $(TCL_OBJS)
@@ -2362,10 +2372,12 @@
 	$(INSTALL_DATA_DIR) $(DISTDIR)/libtommath
 	@echo cp -r $(TOP_DIR)/libtommath $(DISTDIR)/libtommath
 	@( cd $(TOP_DIR)/libtommath; find . -type f -print ) \
 	    | ( cd $(TOP_DIR)/libtommath ; xargs tar cf - ) \
 	    | ( cd $(DISTDIR)/libtommath ; tar xfp - )
+	$(INSTALL_DATA_DIR) $(DISTDIR)/utf8proc
+	$(DIST_INSTALL_DATA) $(UTF8PROC_DIR)/*.[ch] $(DISTDIR)/utf8proc
 	$(INSTALL_DATA_DIR) $(DISTDIR)/tests
 	$(DIST_INSTALL_DATA) $(TOP_DIR)/license.terms $(DISTDIR)/tests
 	$(DIST_INSTALL_DATA) $(TOP_DIR)/tests/*.test $(TOP_DIR)/tests/README \
 		$(TOP_DIR)/tests/*.bench $(TOP_DIR)/tests/*.tar.gz \
 		$(TOP_DIR)/tests/httpd $(TOP_DIR)/tests/*.tcl \

Index: win/Makefile.in
==================================================================
--- win/Makefile.in
+++ win/Makefile.in
@@ -108,10 +108,11 @@
 PKGS_DIR		= $(TOP_DIR)/pkgs
 TOOL_DIR		= $(TOP_DIR)/tools
 ZLIB_DIR		= $(COMPAT_DIR)/zlib
 MINIZIP_DIR		= $(ZLIB_DIR)/contrib/minizip
 TOMMATH_DIR		= $(TOP_DIR)/libtommath
+UTF8PROC_DIR		= $(TOP_DIR)/utf8proc
 
 # Converts a POSIX path to a Windows native path.
 CYGPATH			= @CYGPATH@
 
 libdir_native	= $(shell $(CYGPATH) '$(libdir)')
@@ -448,10 +449,11 @@
 	bn_s_mp_sqr.${OBJEXT} \
 	bn_s_mp_sub.${OBJEXT} \
 	bn_s_mp_toom_mul.${OBJEXT} \
 	bn_s_mp_toom_sqr.${OBJEXT}
 
+UTF8PROC_OBJS = utf8proc.${OBJEXT}
 
 WIN_OBJS = \
 	tclWin32Dll.$(OBJEXT) \
 	tclWinChan.$(OBJEXT) \
 	tclWinConsole.$(OBJEXT) \
@@ -492,11 +494,11 @@
 	inftrees.$(OBJEXT) \
 	trees.$(OBJEXT) \
 	uncompr.$(OBJEXT) \
 	zutil.$(OBJEXT)
 
-TCL_OBJS = ${GENERIC_OBJS} ${WIN_OBJS} @ZLIB_OBJS@ @TOMMATH_OBJS@
+TCL_OBJS = ${GENERIC_OBJS} ${UTF8PROC_OBJS} ${WIN_OBJS} @ZLIB_OBJS@ @TOMMATH_OBJS@
 
 TCL_DOCS = "$(ROOT_DIR_NATIVE)"/doc/*.[13n]
 
 all: binaries libraries doc packages
 
@@ -682,10 +684,12 @@
 # TIP #430, ZipFS Support
 tclZipfs.${OBJEXT}: $(GENERIC_DIR)/tclZipfs.c
 	$(CC) -c $(CC_SWITCHES) -DBUILD_tcl \
 	$(ZLIB_INCLUDE) -I$(MINIZIP_DIR_NATIVE)  @DEPARG@ $(CC_OBJNAME)
 
+utf8proc.${OBJEXT}: $(UTF8PROC_DIR)/utf8proc.c
+	$(CC) -c $(CC_SWITCHES) -DUNICODE -D_UNICODE -DUTF8PROC_EXPORTS @DEPARG@ $(CC_OBJNAME)
 
 # TIP #59, embedding of configuration information into the binary library.
 #
 # Part of Tcl's configuration information are the paths where it was installed
 # and where it will look for its libraries (which can be different). We derive

Index: win/makefile.vc
==================================================================
--- win/makefile.vc
+++ win/makefile.vc
@@ -222,10 +222,12 @@
 TCLDDELIB	= $(OUT_DIR)\$(TCLDDELIBNAME)
 
 TCLTEST		= $(OUT_DIR)\$(PROJECT)test$(VERSION)$(SUFX:t=).exe
 TCLTESTRAW	= $(TCLTEST:.exe=-raw.exe)
 
+UTF8PROCDIR	= $(ROOT)\utf8proc
+
 TCLSHOBJS = \
 	$(TMP_DIR)\tclAppInit.obj \
 	$(TMP_DIR)\tclsh.res
 
 TCLTESTOBJS = \
@@ -333,11 +335,12 @@
 	$(TMP_DIR)\tclTrace.obj \
 	$(TMP_DIR)\tclUtf.obj \
 	$(TMP_DIR)\tclUtil.obj \
 	$(TMP_DIR)\tclVar.obj \
 	$(TMP_DIR)\tclZipfs.obj \
-	$(TMP_DIR)\tclZlib.obj
+	$(TMP_DIR)\tclZlib.obj \
+	$(TMP_DIR)\utf8proc.obj \
 
 !if $(STATIC_BUILD)
 ZLIBOBJS = \
 	$(TMP_DIR)\adler32.obj \
 	$(TMP_DIR)\compress.obj \
@@ -1021,10 +1024,15 @@
 # Implicit rules that are not covered by the common ones defined in
 # rules.vc. A limitation exists with nmake that requires that
 # source directory can not contain spaces in the path.  This an
 # absolute.
 #---------------------------------------------------------------------
+
+{$(UTF8PROCDIR)}.c{$(TMP_DIR)}.obj::
+	$(cc32) $(pkgcflags) -DUTF8PROC_EXPORTS -Fo$(TMP_DIR)\ @<<
+$<
+<<
 
 {$(TOMMATHDIR)}.c{$(TMP_DIR)}.obj::
 	$(cc32) $(pkgcflags) -Fo$(TMP_DIR)\ @<<
 $<
 <<