diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
index d4113736b544b..95ddaab7f44b5 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
@@ -29,5 +29,5 @@ RUN sh /scripts/sccache.sh
 ENV NO_DEBUG_ASSERTIONS=1
 ENV NO_OVERFLOW_CHECKS=1
 
-ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu
-ENV RUST_CHECK_TARGET check-aux
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu"
+ENV RUST_CHECK_TARGET="check-aux"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-debug/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-debug/Dockerfile
index 54b13c4397f47..5287d6b8956ff 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-debug/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-debug/Dockerfile
@@ -29,20 +29,19 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
-ENV RUSTBUILD_FORCE_CLANG_BASED_TESTS 1
+ENV RUSTBUILD_FORCE_CLANG_BASED_TESTS="1"
 
 # llvm.use-linker conflicts with downloading CI LLVM
-ENV NO_DOWNLOAD_CI_LLVM 1
+ENV NO_DOWNLOAD_CI_LLVM="1"
 
-ENV RUST_CONFIGURE_ARGS \
-      --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
       --enable-debug \
       --enable-lld \
       --set rust.debuginfo-level-tests=2 \
       --set llvm.use-linker=lld \
       --set target.x86_64-unknown-linux-gnu.linker=clang \
       --set target.x86_64-unknown-linux-gnu.cc=clang \
-      --set target.x86_64-unknown-linux-gnu.cxx=clang++
+      --set target.x86_64-unknown-linux-gnu.cxx=clang++"
 
 # This job checks:
 # - That ui tests can be built with `-Cdebuginfo=1`
@@ -53,7 +52,6 @@ ENV RUST_CONFIGURE_ARGS \
 # - That the tests with `//@ needs-force-clang-based-tests` pass, since they
 #   don't run by default unless RUSTBUILD_FORCE_CLANG_BASED_TESTS is set.
 
-ENV SCRIPT \
-  python3 ../x.py --stage 2 build && \
+ENV SCRIPT="python3 ../x.py --stage 2 build && \
   python3 ../x.py --stage 2 test tests/ui && \
-  python3 ../x.py --stage 2 test tests/run-make tests/run-make-cargo
+  python3 ../x.py --stage 2 test tests/run-make tests/run-make-cargo"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
index 5bafd89cfd91d..5ab44df7a8033 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
@@ -1,5 +1,5 @@
 # Runs `distcheck`, which is a collection of smoke tests:
-# 
+#
 # - Run `make check` from an unpacked dist tarball to make sure we can at the
 #   minimum run check steps from those sources.
 # - Check that selected dist components at least have expected directory shape
@@ -34,6 +34,6 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 # Make distcheck builds faster
-ENV DISTCHECK_CONFIGURE_ARGS "--enable-sccache"
+ENV DISTCHECK_CONFIGURE_ARGS="--enable-sccache"
 
-ENV SCRIPT python3 ../x.py test distcheck
+ENV SCRIPT="python3 ../x.py test distcheck"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-gcc/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-gcc/Dockerfile
index f9c1ea531add5..2208ed3ffbe15 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-gcc/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-gcc/Dockerfile
@@ -31,15 +31,14 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
-ENV NO_DEBUG_ASSERTIONS 1
-ENV RUST_CONFIGURE_ARGS \
- --build=x86_64-unknown-linux-gnu \
+ENV NO_DEBUG_ASSERTIONS="1"
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs \
  --set llvm.libzstd=true \
- --set 'rust.codegen-backends=[\"llvm\",\"gcc\"]'
-ENV SCRIPT python3 ../x.py \
+ --set rust.codegen-backends=[\\\"llvm\\\",\\\"gcc\\\"]"
+ENV SCRIPT="python3 ../x.py \
   --stage 2 \
   test tests \
   --test-codegen-backend gcc \
@@ -51,4 +50,4 @@ ENV SCRIPT python3 ../x.py \
   --skip tests/rustdoc-js-std \
   --skip tests/rustdoc-json \
   --skip tests/rustdoc-ui \
-  --set 'rust.codegen-backends=[\"llvm\",\"gcc\"]'
+  --set rust.codegen-backends=[\\\"llvm\\\",\\\"gcc\\\"]"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
index 92c2631000f9e..c239661a43a66 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile
@@ -44,16 +44,15 @@ RUN sh /scripts/sccache.sh
 
 # We are disabling CI LLVM since this builder is intentionally using a host
 # LLVM, rather than the typical src/llvm-project LLVM.
-ENV NO_DOWNLOAD_CI_LLVM 1
-ENV EXTERNAL_LLVM 1
+ENV NO_DOWNLOAD_CI_LLVM="1"
+ENV EXTERNAL_LLVM="1"
 
 # Using llvm-link-shared due to libffi issues -- see #34486
-ENV RUST_CONFIGURE_ARGS \
-      --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
       --llvm-root=/usr/lib/llvm-20 \
       --enable-llvm-link-shared \
       --set rust.randomize-layout=true \
-      --set rust.thin-lto-import-instr-limit=10
+      --set rust.thin-lto-import-instr-limit=10"
 
 COPY scripts/shared.sh /scripts/
 
@@ -63,4 +62,4 @@ COPY scripts/x86_64-gnu-llvm3.sh /scripts/
 COPY scripts/stage_2_test_set1.sh /scripts/
 COPY scripts/stage_2_test_set2.sh /scripts/
 
-ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
+ENV SCRIPT="Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-21/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-21/Dockerfile
index f0314854411f2..fc96735521077 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-21/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-21/Dockerfile
@@ -44,16 +44,15 @@ RUN sh /scripts/sccache.sh
 
 # We are disabling CI LLVM since this builder is intentionally using a host
 # LLVM, rather than the typical src/llvm-project LLVM.
-ENV NO_DOWNLOAD_CI_LLVM 1
-ENV EXTERNAL_LLVM 1
+ENV NO_DOWNLOAD_CI_LLVM="1"
+ENV EXTERNAL_LLVM="1"
 
 # Using llvm-link-shared due to libffi issues -- see #34486
-ENV RUST_CONFIGURE_ARGS \
-      --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
       --llvm-root=/usr/lib/llvm-21 \
       --enable-llvm-link-shared \
       --set rust.randomize-layout=true \
-      --set rust.thin-lto-import-instr-limit=10
+      --set rust.thin-lto-import-instr-limit=10"
 
 COPY scripts/shared.sh /scripts/
 
@@ -63,4 +62,4 @@ COPY scripts/x86_64-gnu-llvm3.sh /scripts/
 COPY scripts/stage_2_test_set1.sh /scripts/
 COPY scripts/stage_2_test_set2.sh /scripts/
 
-ENV SCRIPT "Must specify DOCKER_SCRIPT for this image"
+ENV SCRIPT="Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
index db4fca71d6376..e478b80044215 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-miri/Dockerfile
@@ -34,11 +34,10 @@ ENV GCC_EXEC_PREFIX="/usr/lib/gcc/"
 
 COPY host-x86_64/x86_64-gnu-miri/check-miri.sh /tmp/
 
-ENV RUST_CONFIGURE_ARGS \
-  --build=x86_64-unknown-linux-gnu \
-  --enable-new-symbol-mangling
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
+  --enable-new-symbol-mangling"
 
-ENV HOST_TARGET x86_64-unknown-linux-gnu
+ENV HOST_TARGET="x86_64-unknown-linux-gnu"
 
 # FIXME(#133381): currently rustc alt builds do *not* have rustc debug
 # assertions enabled! Therefore, we cannot force download CI rustc.
@@ -46,4 +45,4 @@ ENV HOST_TARGET x86_64-unknown-linux-gnu
 
 COPY scripts/shared.sh /scripts/
 
-ENV SCRIPT /tmp/check-miri.sh ../x.py
+ENV SCRIPT="/tmp/check-miri.sh ../x.py"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
index 854c36ee01c19..6020dc8877c16 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
@@ -22,8 +22,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
-ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
   --disable-optimize-tests \
-  --set rust.test-compare-mode
-ENV SCRIPT python3 ../x.py test --stage 1 --set rust.optimize=false library/std \
-  && python3 ../x.py --stage 2 test
+  --set rust.test-compare-mode"
+ENV SCRIPT="python3 ../x.py test --stage 1 --set rust.optimize=false library/std \
+  && python3 ../x.py --stage 2 test"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index 278e40eb71fac..3eb424ceef4a3 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -76,12 +76,11 @@ COPY scripts/nodejs.sh /scripts/
 RUN sh /scripts/nodejs.sh /node
 ENV PATH="/node/bin:${PATH}"
 
-ENV RUST_CONFIGURE_ARGS \
-  --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
   --save-toolstates=/tmp/toolstate/toolstates.json \
-  --enable-new-symbol-mangling
+  --enable-new-symbol-mangling"
 
-ENV HOST_TARGET x86_64-unknown-linux-gnu
+ENV HOST_TARGET="x86_64-unknown-linux-gnu"
 
 # FIXME(#133381): currently rustc alt builds do *not* have rustc debug
 # assertions enabled! Therefore, we cannot force download CI rustc.
@@ -89,5 +88,5 @@ ENV HOST_TARGET x86_64-unknown-linux-gnu
 
 COPY scripts/shared.sh /scripts/
 
-ENV SCRIPT /tmp/checktools.sh ../x.py && \
-  python3 ../x.py test tests/rustdoc-gui --stage 2 --test-args "'--jobs 1'"
+ENV SCRIPT="/tmp/checktools.sh ../x.py && \
+  python3 ../x.py test tests/rustdoc-gui --stage 2 --test-args '--jobs 1'"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
index 83c2aa8cfb3b7..7ca2dbb7d9f36 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
@@ -24,10 +24,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
-ENV RUST_CONFIGURE_ARGS \
- --build=x86_64-unknown-linux-gnu \
+ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs \
- --set llvm.libzstd=true
-ENV SCRIPT python3 ../x.py --stage 2 test
+ --set llvm.libzstd=true"
+ENV SCRIPT="python3 ../x.py --stage 2 test"