diff --git a/ci/scripts/build.linux.script.sh b/ci/scripts/build.linux.script.sh
new file mode 100644
index 000000000..d00edbfda
--- /dev/null
+++ b/ci/scripts/build.linux.script.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+set -x
+
+# Create and enter build directory.
+rootdir=`pwd`
+mkdir -p ${EIGEN_CI_BUILDDIR}
+cd ${EIGEN_CI_BUILDDIR}
+
+# Configure build.
+cmake -G Ninja                                                   \
+  -DCMAKE_CXX_COMPILER=${EIGEN_CI_CXX_COMPILER}                  \
+  -DCMAKE_C_COMPILER=${EIGEN_CI_C_COMPILER}                      \
+  -DCMAKE_CXX_COMPILER_TARGET=${EIGEN_CI_CXX_COMPILER_TARGET}    \
+  ${EIGEN_CI_ADDITIONAL_ARGS} ${rootdir}
+
+target=""
+if [[ ${EIGEN_CI_BUILD_TARGET} ]]; then
+  target="--target ${EIGEN_CI_BUILD_TARGET}"
+fi
+
+# Builds (particularly gcc) sometimes get killed, potentially when running
+# out of resources.  In that case, keep trying to build the remaining
+# targets (k0), then try to build again with a single thread (j1) to minimize
+# resource use.
+cmake --build . ${target} -- -k0 || cmake --build . ${target} -- -k0 -j1
+
+# Return to root directory.
+cd ${rootdir}
+
+set +x
diff --git a/ci/scripts/build.windows.script.ps1 b/ci/scripts/build.windows.script.ps1
new file mode 100644
index 000000000..2249d008d
--- /dev/null
+++ b/ci/scripts/build.windows.script.ps1
@@ -0,0 +1,44 @@
+# Find Visual Studio installation directory.
+$VS_INSTALL_DIR = &"${Env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath
+
+# Run VCVarsAll.bat initialization script and extract environment variables.
+# http://allen-mack.blogspot.com/2008/03/replace-visual-studio-command-prompt.html
+cmd.exe /c "`"${VS_INSTALL_DIR}\VC\Auxiliary\Build\vcvarsall.bat`" $EIGEN_CI_MSVC_ARCH -vcvars_ver=$EIGEN_CI_MSVC_VER & set" |
+  foreach {
+    if ($_ -match "=") {
+      $v = $_.split("="); set-item -force -path "ENV:\$($v[0])" -value "$($v[1])"
+    }
+  }
+
+# Create and enter build directory.
+$rootdir = Get-Location
+if (-Not (Test-Path ${EIGEN_CI_BUILDDIR})) {
+    mkdir $EIGEN_CI_BUILDDIR
+}
+cd $EIGEN_CI_BUILDDIR
+
+# We need to split EIGEN_CI_ADDITIONAL_ARGS, otherwise they are interpreted
+# as a single argument.  Split by space, unless double-quoted.
+$split_args = [regex]::Split(${EIGEN_CI_ADDITIONAL_ARGS}, ' (?=(?:[^"]|"[^"]*")*$)' )
+
+# Configure build.
+cmake -G Ninja -DCMAKE_BUILD_TYPE=MinSizeRel `
+      -DEIGEN_TEST_CUSTOM_CXX_FLAGS="${EIGEN_CI_TEST_CUSTOM_CXX_FLAGS}" `
+      ${split_args} "${rootdir}"
+
+$target = ""
+if (${EIGEN_CI_BUILD_TARGET}) {
+  $target = "--target ${EIGEN_CI_BUILD_TARGET}"
+}
+
+# Windows builds sometimes fail due heap errors. In that case, try
+# building the rest, then try to build again with a single thread.
+cmake --build . ${target} -- -k0 || cmake --build . ${target} -- -k0 -j1
+
+$success = $LASTEXITCODE
+
+# Return to root directory.
+cd ${rootdir}
+
+# Explicitly propagate exit code to indicate pass/failure of build command.
+if($success -ne 0) { Exit $success }
diff --git a/ci/scripts/build_and_install_doxygen.sh b/ci/scripts/build_and_install_doxygen.sh
new file mode 100644
index 000000000..9cb47b760
--- /dev/null
+++ b/ci/scripts/build_and_install_doxygen.sh
@@ -0,0 +1,6 @@
+git clone --depth 1 --branch $1 https://github.com/doxygen/doxygen.git
+cmake -B doxygen/.build -G Ninja                                 \
+  -DCMAKE_CXX_COMPILER=${EIGEN_CI_CXX_COMPILER}                  \
+  -DCMAKE_C_COMPILER=${EIGEN_CI_C_COMPILER}                      \
+  doxygen
+cmake --build doxygen/.build -t install