diff --git a/documentation/Makefile b/documentation/Makefile
index 541390b2a1..30bb71cb31 100644
--- a/documentation/Makefile
+++ b/documentation/Makefile
@@ -61,9 +61,12 @@ epub: $(PNGs)
 	$(SOURCEDIR)/set_versions.py
 	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 
+# Note: we need to pass buf_size here (which is also configurable from
+# texmf.cnf), to avoid following error:
+#   Unable to read an entire line---bufsize=200000. Please increase buf_size in texmf.cnf.
 latexpdf: $(PDFs)
 	$(SOURCEDIR)/set_versions.py
-	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	buf_size=10000000 $(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 
 all: html epub latexpdf
 
diff --git a/documentation/conf.py b/documentation/conf.py
index 9e87df0564..c7dd4e03fc 100644
--- a/documentation/conf.py
+++ b/documentation/conf.py
@@ -158,9 +158,14 @@ html_last_updated_fmt = '%b %d, %Y'
 # Remove the trailing 'dot' in section numbers
 html_secnumber_suffix = " "
 
+# We need XeTeX to process special unicode character, sometimes the contributor
+# list from the release note contains those.
+# See https://docs.readthedocs.io/en/stable/guides/pdf-non-ascii-languages.html.
+latex_engine = 'xelatex'
+latex_use_xindy = False
 latex_elements = {
     'passoptionstopackages': '\\PassOptionsToPackage{bookmarksdepth=5}{hyperref}',
-    'preamble': '\\setcounter{tocdepth}{2}',
+    'preamble': '\\usepackage[UTF8]{ctex}\n\\setcounter{tocdepth}{2}',
 }
 
 # Make the EPUB builder prefer PNG to SVG because of issues rendering Inkscape SVG