diff --git a/configure b/configure
index 38f3e3b00c6..b7053c5c54f 100755
--- a/configure
+++ b/configure
@@ -599,6 +599,7 @@ opt debug-assertions 0 "build with debugging assertions"
 opt fast-make 0 "use .gitmodules as timestamp for submodule deps"
 opt ccache 0 "invoke gcc/clang via ccache to reuse object files between builds"
 opt local-rust 0 "use an installed rustc rather than downloading a snapshot"
+opt local-rebuild 0 "use an installed rustc matching the current version, for rebuilds"
 opt llvm-static-stdcpp 0 "statically link to libstdc++ for LLVM"
 opt rpath 1 "build rpaths into rustc itself"
 opt stage0-landing-pads 1 "enable landing pads during bootstrap with stage0"
@@ -847,6 +848,16 @@ then
     BIN_SUF=.exe
 fi
 
+# --enable-local-rebuild implies --enable-local-rust too
+if [ -n "$CFG_ENABLE_LOCAL_REBUILD" ]
+then
+    if [ -z "$CFG_ENABLE_LOCAL_RUST" ]
+    then
+        CFG_ENABLE_LOCAL_RUST=1
+        putvar CFG_ENABLE_LOCAL_RUST
+    fi
+fi
+
 if [ -n "$CFG_ENABLE_LOCAL_RUST" ]
 then
     system_rustc=$(which rustc)
diff --git a/mk/main.mk b/mk/main.mk
index 493b6105133..6feb53ec7b1 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -34,7 +34,14 @@ CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE)$(CFG_EXTRA_FILENAME) | $(C
 # intentionally not "secure" by any definition, this is largely just a deterrent
 # from users enabling unstable features on the stable compiler.
 CFG_BOOTSTRAP_KEY=$(CFG_FILENAME_EXTRA)
+
+# The stage0 compiler needs to use the previous key recorded in src/stage0.txt,
+# except for local-rebuild when it just uses the same current key.
+ifdef CFG_ENABLE_LOCAL_REBUILD
+CFG_BOOTSTRAP_KEY_STAGE0=$(CFG_BOOTSTRAP_KEY)
+else
 CFG_BOOTSTRAP_KEY_STAGE0=$(shell grep 'rustc_key' $(S)src/stage0.txt | sed 's/rustc_key: '//)
+endif
 
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
@@ -526,6 +533,11 @@ ifneq ($(strip $(CFG_BUILD)),$(strip $(3)))
 CFGFLAG$(1)_T_$(2)_H_$(3) = stage1
 
 RPATH_VAR$(1)_T_$(2)_H_$(3) := $$(TARGET_RPATH_VAR1_T_$(2)_H_$$(CFG_BUILD))
+else
+ifdef CFG_ENABLE_LOCAL_REBUILD
+# Assume the local-rebuild rustc already has stage1 features too.
+CFGFLAG$(1)_T_$(2)_H_$(3) = stage1
+endif
 endif
 endif