Try cross compiling

openssl/test/build.sh

 #!/bin/bash
 set -e
 
-if [ $TRAVIS_OS_NAME -eq "osx" ]; then
+if [ $TRAVIS_OS_NAME == "osx" ]; then
     exit 0
 fi
 
+if [ $TARGET != "" ]; then
+    FLAGS="os/compiler=$TARGET-"
+fi
+
 mkdir /tmp/openssl
 cd /tmp/openssl
 curl https://openssl.org/source/openssl-1.0.2e.tar.gz | tar --strip-components=1 -xzf -
-./config --prefix=$HOME/openssl shared
+./config --prefix=$HOME/openssl shared $FLAGS
 make
 make install

openssl/test/run.sh

 #!/bin/bash
 set -e
 
+MAIN_TARGETS=https://static.rust-lang.org/dist
+
 if [ $TEST_FEATURES == "true" ]; then
     FEATURES="tlsv1_2 tlsv1_1 dtlsv1 dtlsv1_2 sslv2 sslv3 aes_xts aes_ctr npn alpn rfc5114 ecdh_auto pkcs5_pbkdf2_hmac"
 fi
@@ -11,4 +13,19 @@ if [ $TRAVIS_OS_NAME != "osx" ]; then
     export LD_LIBRARY_PATH=$HOME/openssl/lib:$LD_LIBRARY_PATH
 fi
 
-cargo test --manifest-path=openssl/Cargo.toml --features "$FEATURES"
+if [ $TARGET != "" ]; then
+    FLAGS="--target=$TARGET"
+    COMMAND="build"
+
+    # Download the rustlib folder from the relevant portion of main distribution's
+    # tarballs.
+    dir=rust-std-$TARGET
+    pkg=rust-std
+    curl -s $MAIN_TARGETS/$pkg-$TRAVIS_RUST_VERSION-$TARGET.tar.gz | \
+      tar xzf - -C $HOME/rust/lib/rustlib --strip-components=4 \
+        $pkg-$TRAVIS_RUST_VERSION-$TARGET/$dir/lib/rustlib/$TARGET
+else
+    COMMAND="test"
+fi
+
+cargo $COMMAND --manifest-path=openssl/Cargo.toml $FLAGS --features "$FEATURES"