diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -44,6 +44,14 @@
 # Install various tools used by the build or the test suite
 RUN apt-get update && apt-get install -y ninja-build python3 python3-sphinx python3-distutils git gdb
 RUN apt-get update && apt-get install -y libc6-dev-i386 # Required to cross-compile to 32 bits
+# Locales for gdb and localization tests
+RUN apt-get update && apt-get install -y language-pack-en language-pack-fr \
+                                         language-pack-ru language-pack-zh-hans
+# These two are not enabled by default so generate them
+RUN printf "fr_CA ISO-8859-1\ncs_CZ ISO-8859-2" >> /etc/locale.gen
+RUN mkdir /usr/local/share/i1en/
+RUN printf "fr_CA ISO-8859-1\ncs_CZ ISO-8859-2" >> /usr/local/share/i1en/SUPPORTED
+RUN locale-gen
 
 # Install Clang <latest>, <latest-1> and ToT, which are the ones we support.
 ENV LLVM_LATEST_VERSION=12