well it's probably quicker to use a tool treating the file as plain text (since the unicode normalisation should not break the xml)
but since you asked on xsl-list (and I don't know off hand of a text normaliser) then you can have an identity template and templates

<xsl:template match="text()">
<xsl:value-of select="normalize-unicode(.)"/>
</xsl:template>

<xsl:template match="@*">
<xsl:attribute name="{name()}" select="normalize-unicode(.)"/>
</xsl:template>

David

<xsl:output method="xml" normalization-form="NFC"/>
<xsl:template match="/">
<xsl:copy-of select="."/>
</xsl:template>

Michael Kay
Saxonica