diff --git a/.dockerignore b/.dockerignore
index 07d8668694..a1d9542c3a 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,2 +1,3 @@
 # kola_temp can include socket files that the build process does not like
 /mantle/_kola_temp
+/bin
diff --git a/Makefile b/Makefile
index 56f583973f..36bbf90ff1 100644
--- a/Makefile
+++ b/Makefile
@@ -31,7 +31,7 @@ else ifeq ($(GOARCH),aarch64)
 endif
 
 bin/coreos-assembler:
-	cd cmd && go build -mod vendor -o ../$@
+	cd cmd && go build $(GOFLAGS) -mod vendor -o ../$@
 .PHONY: bin/coreos-assembler
 
 .%.shellchecked: %
diff --git a/docs/building-fcos.md b/docs/building-fcos.md
index 774a876f07..f49a052c3f 100644
--- a/docs/building-fcos.md
+++ b/docs/building-fcos.md
@@ -101,7 +101,6 @@ cosa() {
               -v ${PWD}:/srv/ --device /dev/kvm --device /dev/fuse                                  \
               --tmpfs /tmp -v /var/tmp:/var/tmp --name cosa                                         \
               ${COREOS_ASSEMBLER_CONFIG_GIT:+-v $COREOS_ASSEMBLER_CONFIG_GIT:/srv/src/config/:ro}   \
-              ${COREOS_ASSEMBLER_GIT:+-v $COREOS_ASSEMBLER_GIT/src/:/usr/lib/coreos-assembler/:ro}  \
               ${COREOS_ASSEMBLER_CONTAINER_RUNTIME_ARGS}                                            \
               ${COREOS_ASSEMBLER_CONTAINER:-$COREOS_ASSEMBLER_CONTAINER_LATEST} "$@"
    rc=$?; set +x; return $rc
@@ -127,9 +126,6 @@ The environment variables are special purpose:
 
 - `COREOS_ASSEMBLER_CONFIG_GIT`: Allows you to specifiy a local directory that
   contains the configs for the ostree you are trying to compose.
-- `COREOS_ASSEMBLER_GIT`: Allows you to specify a local directory that contains
-  the CoreOS Assembler scripts. This allows for quick hacking on the assembler
-  itself.
 - `COREOS_ASSEMBLER_CONTAINER_RUNTIME_ARGS`: Allows for adding arbitrary mounts
   or args to the container runtime.
 - `COREOS_ASSEMBLER_CONTAINER`: Allows for overriding the default assembler
diff --git a/docs/devel.md b/docs/devel.md
index 27718070d5..4923bed3ab 100644
--- a/docs/devel.md
+++ b/docs/devel.md
@@ -12,18 +12,18 @@ guides if you are looking for how to use the CoreOS Assembler.
 1. TOC
 {:toc}
 
-## Hacking on CoreOS Assembler Scripts
+## Hacking on CoreOS Assembler 
 
-If you find yourself wanting to hack on CoreOS Assembler itself then you can
-easily mount the scripts into the container and prevent rebuilding the
-container to test every change. This can be done using the
-`COREOS_ASSEMBLER_GIT` env var.
+You could rerun `podman build -t localhost/cosa` every time you make
+a change, but it'd be very expensive to do so. 
 
-```
-$ export COREOS_ASSEMBLER_GIT=/path/to/github.com/coreos/coreos-assembler/
-$ cosa init https://github.com/coreos/fedora-coreos-config.git
-$ cosa fetch && cosa build
-```
+Instead, you can use [hack/Dockerfile].  There are instructions in that
+file.  This avoids redownloading and reinstalling all of the
+dependency RPMs.
+
+For even faster workflow, you can just bind mount in binaries from
+your host or from another container by adding additional bind mounts,
+and then copy files into your coreos-assembler container more manually.
 
 ## Installing cosa inside an existing container
 
diff --git a/hack/Dockerfile b/hack/Dockerfile
new file mode 100644
index 0000000000..1c6c7fd5c4
--- /dev/null
+++ b/hack/Dockerfile
@@ -0,0 +1,8 @@
+# Use this for quicker iteration on coros-assembler; from the toplevel run e.g.:
+# podman build -t localhost/cosa -f hack/Dockerfile .
+FROM quay.io/coreos-assembler/coreos-assembler:latest
+WORKDIR /src
+COPY . .
+USER root
+RUN env GOFLAGS="-buildvcs=false" make && make install
+USER builder
diff --git a/mantle/build b/mantle/build
index 4bd43f8c53..8f7bc29e03 100755
--- a/mantle/build
+++ b/mantle/build
@@ -26,7 +26,7 @@ ldflags="-X ${REPO_PATH}/version.Version=${version}"
 host_build() {
     local cmd=$1; shift
     echo "Building $cmd"
-    go build \
+    go build ${GOFLAGS:-} \
         -ldflags "${ldflags}" \
         -mod vendor \
         -o "bin/$cmd" \
@@ -41,7 +41,7 @@ cross_static_build() {
         mkdir -p "bin/$a"
         echo "Building $a/$cmd (static)"
         CGO_ENABLED=0 GOARCH=${BASEARCH_TO_GOARCH[$a]} \
-        go build \
+        go build ${GOFLAGS:-} \
             -ldflags "${ldflags} -extldflags=-static" \
             -mod vendor \
             -o "bin/$a/$cmd" \