diff --git a/Makefile b/Makefile
index 3b1c6f0d0bc7b..d96497ca94d2e 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ default: $(JULIA_BUILD_MODE) # contains either "debug" or "release"
 all: debug release
 
 # sort is used to remove potential duplicates
-DIRS := $(sort $(build_bindir) $(build_depsbindir) $(build_libdir) $(build_private_libdir) $(build_libexecdir) $(build_includedir) $(build_includedir)/julia $(build_sysconfdir)/julia $(build_datarootdir)/julia $(build_datarootdir)/julia/src $(build_datarootdir)/julia/stdlib $(build_man1dir))
+DIRS := $(sort $(build_bindir) $(build_depsbindir) $(build_libdir) $(build_private_libdir) $(build_libexecdir) $(build_includedir) $(build_includedir)/julia $(build_sysconfdir)/julia $(build_datarootdir)/julia $(build_datarootdir)/julia/stdlib $(build_man1dir))
 ifneq ($(BUILDROOT),$(JULIAHOME))
 BUILDDIRS := $(BUILDROOT) $(addprefix $(BUILDROOT)/,base src src/flisp src/support src/clangsa cli doc deps stdlib test test/clangsa test/embedding test/llvmpasses)
 BUILDDIRMAKE := $(addsuffix /Makefile,$(BUILDDIRS)) $(BUILDROOT)/sysimage.mk
@@ -39,13 +39,13 @@ configure:
 endif
 
 $(foreach dir,$(DIRS),$(eval $(call dir_target,$(dir))))
-$(eval $(call symlink_target,$(JULIAHOME)/test,$$(build_datarootdir)/julia,test))
+$(foreach link,base $(JULIAHOME)/test,$(eval $(call symlink_target,$(link),$$(build_datarootdir)/julia,$(notdir $(link)))))
 
 julia_flisp.boot.inc.phony: julia-deps
 	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT)/src julia_flisp.boot.inc.phony
 
 # Build the HTML docs (skipped if already exists, notably in tarballs)
-$(BUILDROOT)/doc/_build/html/en/index.html: $(shell find $(BUILDROOT)/base $(BUILDROOT)/doc \( -path $(BUILDROOT)/doc/_build -o -path $(BUILDROOT)/doc/deps \) -prune -o -type f -print)
+$(BUILDROOT)/doc/_build/html/en/index.html: $(shell find $(BUILDROOT)/base $(BUILDROOT)/doc \( -path $(BUILDROOT)/doc/_build -o -path $(BUILDROOT)/doc/deps -o -name *_constants.jl -o -name *_h.jl -o -name version_git.jl \) -prune -o -type f -print)
 	@$(MAKE) docs
 
 julia-symlink: julia-cli-$(JULIA_BUILD_MODE)
@@ -58,7 +58,7 @@ ifndef JULIA_VAGRANT_BUILD
 endif
 endif
 
-julia-deps: | $(DIRS) $(build_datarootdir)/julia/test
+julia-deps: | $(DIRS) $(build_datarootdir)/julia/base $(build_datarootdir)/julia/test
 	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT)/deps
 
 # `julia-stdlib` depends on `julia-deps` so that the fake JLL stdlibs can copy in their Artifacts.toml files.
@@ -86,14 +86,9 @@ julia-sysimg-ji : julia-stdlib julia-base julia-cli-$(JULIA_BUILD_MODE) julia-sr
 julia-sysimg-bc : julia-stdlib julia-base julia-cli-$(JULIA_BUILD_MODE) julia-src-$(JULIA_BUILD_MODE) | $(build_private_libdir)
 	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT) -f sysimage.mk sysimg-bc JULIA_EXECUTABLE='$(JULIA_EXECUTABLE)'
 
-$(JULIA_SYSIMG_release): julia-sysimg-ji julia-src-release
-	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT) -f sysimage.mk sysimg-release
-$(JULIA_SYSIMG_debug) : julia-sysimg-ji julia-src-debug
-	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT) -f sysimage.mk sysimg-debug
+julia-sysimg-release julia-sysimg-debug : julia-sysimg-% : julia-sysimg-ji julia-src-%
+	@$(MAKE) $(QUIET_MAKE) -C $(BUILDROOT) -f sysimage.mk sysimg-$*
 
-julia-sysimg-release : $(JULIA_SYSIMG_release)
-julia-sysimg-debug : $(JULIA_SYSIMG_debug)
-julia-base-cache: $(build_datarootdir)/julia/base.cache
 julia-debug julia-release : julia-% : julia-sysimg-% julia-src-% julia-symlink julia-libccalltest julia-libllvmcalltest julia-base-cache
 
 debug release : % : julia-%
@@ -163,10 +158,10 @@ $(build_datarootdir)/julia/julia-config.jl: $(JULIAHOME)/contrib/julia-config.jl
 $(build_depsbindir)/stringreplace: $(JULIAHOME)/contrib/stringreplace.c | $(build_depsbindir)
 	@$(call PRINT_CC, $(HOSTCC) -o $(build_depsbindir)/stringreplace $(JULIAHOME)/contrib/stringreplace.c)
 
-$(build_datarootdir)/julia/base.cache: $(JULIA_SYSIMG) | $(DIRS) $(build_datarootdir)/julia
+julia-base-cache: julia-sysimg-$(JULIA_BUILD_MODE) | $(DIRS) $(build_datarootdir)/julia
 	@JULIA_BINDIR=$(call cygpath_w,$(build_bindir)) WINEPATH="$(call cygpath_w,$(build_bindir));$$WINEPATH" \
 		$(call spawn, $(JULIA_EXECUTABLE) --startup-file=no $(call cygpath_w,$(JULIAHOME)/etc/write_base_cache.jl) \
-		$(call cygpath_w,$@))
+		$(call cygpath_w,$(build_datarootdir)/julia/base.cache))
 
 # public libraries, that are installed in $(prefix)/lib
 ifeq ($(JULIA_BUILD_MODE),release)
@@ -319,9 +314,10 @@ else ifeq ($(JULIA_BUILD_MODE),debug)
 endif
 
 	# Copy in all .jl sources as well
-	mkdir -p $(DESTDIR)$(datarootdir)/julia/src $(DESTDIR)$(datarootdir)/julia/test
-	cp -R -L $(build_datarootdir)/julia/* $(DESTDIR)$(datarootdir)/julia
+	mkdir -p $(DESTDIR)$(datarootdir)/julia/base $(DESTDIR)$(datarootdir)/julia/test
+	cp -R -L $(JULIAHOME)/base/* $(DESTDIR)$(datarootdir)/julia/base
 	cp -R -L $(JULIAHOME)/test/* $(DESTDIR)$(datarootdir)/julia/test
+	cp -R -L $(build_datarootdir)/julia/* $(DESTDIR)$(datarootdir)/julia
 	# Copy documentation
 	cp -R -L $(BUILDROOT)/doc/_build/html $(DESTDIR)$(docdir)/
 	# Remove various files which should not be installed
@@ -469,7 +465,7 @@ ifneq ($(BUILDROOT),$(JULIAHOME))
 	$(error make light-source-dist does not work in out-of-tree builds)
 endif
 	# Save git information
-	-@$(MAKE) -C $(JULIAHOME)/base version_git.jl
+	-@$(MAKE) -C $(JULIAHOME)/base version_git.jl.phony
 
 	# Create file light-source-dist.tmp to hold all the filenames that go into the tarball
 	echo "base/version_git.jl" > light-source-dist.tmp
diff --git a/base/.gitignore b/base/.gitignore
index f7460230f217b..e572b8ea229d0 100644
--- a/base/.gitignore
+++ b/base/.gitignore
@@ -1,4 +1,10 @@
+/features_h.jl
+/pcre_h.jl
+/errno_h.jl
+/build_h.jl
 /build_h.jl.phony
+/file_constants.jl
+/uv_constants.jl
 /version_git.jl
 /version_git.jl.phony
 /userimg.jl
diff --git a/base/Base.jl b/base/Base.jl
index aa29a6d08c943..5c84cd8b063a7 100644
--- a/base/Base.jl
+++ b/base/Base.jl
@@ -157,8 +157,18 @@ using .Iterators: Flatten, Filter, product  # for generators
 include("namedtuple.jl")
 
 # For OS specific stuff
-include("../build_h.jl")
-include("../version_git.jl")
+# We need to strcat things here, before strings are really defined
+function strcat(x::String, y::String)
+    out = ccall(:jl_alloc_string, Ref{String}, (Csize_t,), Core.sizeof(x) + Core.sizeof(y))
+    GC.@preserve x y out begin
+        out_ptr = unsafe_convert(Ptr{UInt8}, out)
+        unsafe_copyto!(out_ptr, unsafe_convert(Ptr{UInt8}, x), Core.sizeof(x))
+        unsafe_copyto!(out_ptr + Core.sizeof(x), unsafe_convert(Ptr{UInt8}, y), Core.sizeof(y))
+    end
+    return out
+end
+include(strcat((length(Core.ARGS)>=2 ? Core.ARGS[2] : ""), "build_h.jl"))     # include($BUILDROOT/base/build_h.jl)
+include(strcat((length(Core.ARGS)>=2 ? Core.ARGS[2] : ""), "version_git.jl")) # include($BUILDROOT/base/version_git.jl)
 
 # These used to be in build_h.jl and are retained for backwards compatibility
 const libblas_name = "libblastrampoline"
diff --git a/base/Makefile b/base/Makefile
index 1c1901e9499fb..1cc050f57fb4c 100644
--- a/base/Makefile
+++ b/base/Makefile
@@ -5,22 +5,7 @@ include $(JULIAHOME)/Make.inc
 
 TAGGED_RELEASE_BANNER := ""
 
-all:
-
-BASE_SRCS := $(patsubst ./%,%,$(shell cd $(SRCDIR) && find . -name \*.jl -and -not -name version_git.jl -and -not -name '*.phony'))
-GENERATED_SRCS := pcre_h.jl errno_h.jl build_h.jl.phony features_h.jl file_constants.jl uv_constants.jl version_git.jl.phony
-
-GENERATED_DSTS := $(addprefix $(build_datarootdir)/julia/src/,$(GENERATED_SRCS))
-BASE_DSTS := $(addprefix $(build_datarootdir)/julia/src/base/,$(BASE_SRCS)) $(GENERATED_DSTS)
-BASE_DIRS := $(sort $(dir $(BASE_DSTS)))
-$(foreach dir,$(BASE_DIRS),$(eval $(call dir_target,$(dir))))
-
-# we might like to add "| $(BASE_DIRS)" here, but that causes many version of 'make' to get confused and fail to build consistently
-$(build_datarootdir)/julia/src/base/%.jl: $(SRCDIR)/%.jl
-	@mkdir -p $(dir $@)
-	cp $< $@
-
-all: $(BASE_DSTS)
+all: $(addprefix $(BUILDDIR)/,pcre_h.jl errno_h.jl build_h.jl.phony features_h.jl file_constants.jl uv_constants.jl version_git.jl.phony)
 
 PCRE_CONST := 0x[0-9a-fA-F]+|[0-9]+|\([\-0-9]+\)
 ifeq ($(USE_SYSTEM_PCRE), 1)
@@ -31,37 +16,29 @@ endif
 
 define parse_features
 @echo "# $(2) features" >> $@
-@$(call PRINT_PERL, cat $(JULIAHOME)/src/features_$(1).h | \
-	perl -lne 'print "const JL_$(2)_$$1 = UInt32($$2)" if /^\s*JL_FEATURE_DEF(?:_NAME)?\(\s*(\w+)\s*,\s*([^,]+)\s*,.*\)\s*(?:\/\/.*)?$$/' >> $@)
+@$(call PRINT_PERL, cat $(SRCDIR)/../src/features_$(1).h | perl -lne 'print "const JL_$(2)_$$1 = UInt32($$2)" if /^\s*JL_FEATURE_DEF(?:_NAME)?\(\s*(\w+)\s*,\s*([^,]+)\s*,.*\)\s*(?:\/\/.*)?$$/' >> $@)
 @echo >> $@
 endef
 
-$(build_datarootdir)/julia/src/features_h.jl: $(JULIAHOME)/src/features_x86.h $(JULIAHOME)/src/features_aarch32.h $(JULIAHOME)/src/features_aarch64.h
-	@mkdir -p $(dir $@)
+$(BUILDDIR)/features_h.jl: $(SRCDIR)/../src/features_x86.h $(SRCDIR)/../src/features_aarch32.h $(SRCDIR)/../src/features_aarch64.h
 	@-rm -f $@
 	@$(call parse_features,x86,X86)
 	@$(call parse_features,aarch32,AArch32)
 	@$(call parse_features,aarch64,AArch64)
 
-$(build_datarootdir)/julia/src/pcre_h.jl: $(PCRE_INCL_PATH)
-	@mkdir -p $(dir $@)
+$(BUILDDIR)/pcre_h.jl: $(PCRE_INCL_PATH)
 	@$(call PRINT_PERL, $(CPP) -D PCRE2_CODE_UNIT_WIDTH=8 -dM $< | perl -nle '/^\s*#define\s+PCRE2_(\w*)\s*\(?($(PCRE_CONST))\)?u?\s*$$/ and print index($$1, "ERROR_") == 0 ? "const $$1 = Cint($$2)" : "const $$1 = UInt32($$2)"' | LC_ALL=C sort > $@)
 
-$(build_datarootdir)/julia/src/errno_h.jl:
-	@mkdir -p $(dir $@)
+$(BUILDDIR)/errno_h.jl:
 	@$(call PRINT_PERL, echo '#include <errno.h>' | $(CPP) -dM - | perl -nle 'print "const $$1 = Int32($$2)" if /^#define\s+(E\w+)\s+(\d+)\s*$$/' | LC_ALL=C sort > $@)
 
-$(build_datarootdir)/julia/src/file_constants.jl: $(JULIAHOME)/src/file_constants.h
-	@mkdir -p $(dir $@)
+$(BUILDDIR)/file_constants.jl: $(SRCDIR)/../src/file_constants.h
 	@$(call PRINT_PERL, $(CPP_STDOUT) -DJULIA $< | perl -nle 'print "$$1 0o$$2" if /^(\s*const\s+[A-z_]+\s+=)\s+(0[0-9]*)\s*$$/; print "$$1" if /^\s*(const\s+[A-z_]+\s+=\s+([1-9]|0x)[0-9A-z]*)\s*$$/' > $@)
 
-$(build_datarootdir)/julia/src/uv_constants.jl: $(JULIAHOME)/src/uv_constants.h $(LIBUV_INC)/uv/errno.h
-	@mkdir -p $(dir $@)
+$(BUILDDIR)/uv_constants.jl: $(SRCDIR)/../src/uv_constants.h $(LIBUV_INC)/uv/errno.h
 	@$(call PRINT_PERL, $(CPP_STDOUT) "-I$(LIBUV_INC)" -DJULIA $< | tail -n 16 > $@)
 
-$(build_datarootdir)/julia/src/build_h.jl.phony: $(BUILDDIR)/build_h.jl.phony
 $(BUILDDIR)/build_h.jl.phony:
-	@mkdir -p $(build_datarootdir)/julia/src
 	@echo "# This file is automatically generated in base/Makefile" > $@
 ifeq ($(XC_HOST),)
 	@echo "const MACHINE = \"$(BUILD_MACHINE)\"" >> $@
@@ -109,44 +86,35 @@ endif
 
 	@# This to ensure that we always rebuild this file, but only when it is modified do we touch build_h.jl,
 	@# ensuring we rebuild the system image as infrequently as possible
-	@if ! cmp -s $@ $(build_datarootdir)/julia/src/build_h.jl; then \
+	@if ! cmp -s $@ build_h.jl; then \
 		$(call PRINT_PERL,) \
-		mv $@ $(build_datarootdir)/julia/src/build_h.jl; \
+		mv $@ build_h.jl; \
 	else \
 		rm -f $@; \
 	fi
 
-$(build_datarootdir)/julia/src/version_git.jl.phony: $(BUILDDIR)/version_git.jl.phony
 $(BUILDDIR)/version_git.jl.phony: $(SRCDIR)/version_git.sh
-	@mkdir -p $(build_datarootdir)/julia/src
-ifneq ($(NO_GIT),1)
-	@sh $< $(SRCDIR) > $@
-else ifeq ($(shell [ -f $(BUILDDIR)/version_git.jl ] && echo "true"), true)
-	@# Give warning if boilerplate git is found here
-	@if grep -q "Default output if git is not available" $(BUILDDIR)/version_git.jl; then \
-	    echo "WARNING: Using boilerplate git version info" >&2; \
-	fi
-	@cp $(BUILDDIR)/version_git.jl $@
-else ifeq ($(shell [ -f $(SRCDIR)/version_git.jl ] && echo "true"), true)
-	@# Give warning if boilerplate git is found here
-	@if grep -q "Default output if git is not available" $(SRCDIR)/version_git.jl; then \
-	    echo "WARNING: Using boilerplate git version info" >&2; \
-	fi
-	@cp $(SRCDIR)/version_git.jl $@
-else
-	$(warning "WARNING: Generating boilerplate git version info")
-	@sh $< $(SRCDIR) NO_GIT > $@
-endif
+ifneq ($(NO_GIT), 1)
+	sh $< $(SRCDIR) > $@
 	@# This to avoid touching version_git.jl when it is not modified,
 	@# so that the system image does not need to be rebuilt.
-	@if ! cmp -s $@ $(build_datarootdir)/julia/src/version_git.jl; then \
+	@if ! cmp -s $@ version_git.jl; then \
 	    $(call PRINT_PERL,) \
-	    mv $@ $(build_datarootdir)/julia/src/version_git.jl; \
+	    mv $@ version_git.jl; \
 	else \
 	    rm -f $@; \
 	fi
-$(BUILDDIR)/version_git.jl: $(SRCDIR)/version_git.sh
-	sh $< $(SRCDIR) > $@
+else
+ifeq ($(shell [ -f $(BUILDDIR)/version_git.jl ] && echo "true"), true)
+	@# Give warning if boilerplate git is used
+	@if grep -q "Default output if git is not available" $(BUILDDIR)/version_git.jl; then \
+	    echo "WARNING: Using boilerplate git version info" >&2; \
+	fi
+else
+	$(warning "WARNING: Generating boilerplate git version info")
+	@sh $(SRCDIR)/version_git.sh $(SRCDIR) NO_GIT > $(BUILDDIR)/version_git.jl
+endif
+endif
 
 ifeq (,$(filter $(OS), WINNT emscripten))
 # For any USE_SYSTEM_* libraries that will be dynamically loaded by libjulia,
@@ -194,7 +162,7 @@ endif
 define symlink_system_library
 libname_$2 := $$(notdir $(call versioned_libname,$2,$3))
 libpath_$2 := $$(shell $$(call spawn,$$(LIBWHICH)) -p $$(libname_$2) 2>/dev/null)
-symlink_$2: $$(build_private_libdir)/$$(libname_$2) .FORCE
+symlink_$2: $$(build_private_libdir)/$$(libname_$2)
 $$(build_private_libdir)/$$(libname_$2):
 	@if [ -e "$$(libpath_$2)" ]; then \
 		REALPATH=$$(libpath_$2); \
@@ -300,10 +268,7 @@ endif
 
 symlink_system_libraries: $(SYMLINK_SYSTEM_LIBRARIES)
 
-.FORCE:
-.PHONY: $(BUILDDIR)/version_git.jl $(BUILDDIR)/version_git.jl.phony $(build_datarootdir)/julia/src/version_git.jl.phony \
-	$(BUILDDIR)/build_h.jl.phony $(build_datarootdir)/julia/src/build_h.jl.phony \
-	clean all .FORCE
+.PHONY: $(BUILDDIR)/build_h.jl.phony $(BUILDDIR)/version_git.jl.phony clean all symlink_*
 
 clean:
 	-rm -f $(BUILDDIR)/pcre_h.jl
@@ -315,5 +280,4 @@ clean:
 	-rm -f $(BUILDDIR)/file_constants.jl
 	-rm -f $(BUILDDIR)/version_git.jl
 	-rm -f $(BUILDDIR)/version_git.jl.phony
-	-rm -rf $(build_datarootdir)/julia/src/*
 	-rm -f $(build_private_libdir)/lib*.$(SHLIB_EXT)*
diff --git a/base/cpuid.jl b/base/cpuid.jl
index 476e4b49fa1dc..48930d8064ba9 100644
--- a/base/cpuid.jl
+++ b/base/cpuid.jl
@@ -21,7 +21,7 @@ Base.:<=(a::ISA, b::ISA) = a.features <= b.features
 Base.:<(a::ISA,  b::ISA) = a.features <  b.features
 Base.isless(a::ISA,  b::ISA) = a < b
 
-include("../features_h.jl")
+include(string(length(Core.ARGS) >= 2 ? Core.ARGS[2] : "", "features_h.jl"))  # include($BUILDROOT/base/features_h.jl)
 
 # Keep in sync with `arch_march_isa_mapping`.
 const ISAs_by_family = Dict(
diff --git a/base/filesystem.jl b/base/filesystem.jl
index ee25c63a557e5..63fe4281f6e59 100644
--- a/base/filesystem.jl
+++ b/base/filesystem.jl
@@ -90,7 +90,7 @@ uv_fs_req_cleanup(req) = ccall(:uv_fs_req_cleanup, Cvoid, (Ptr{Cvoid},), req)
 include("path.jl")
 include("stat.jl")
 include("file.jl")
-include("../file_constants.jl")
+include(string(length(Core.ARGS) >= 2 ? Core.ARGS[2] : "", "file_constants.jl"))  # include($BUILDROOT/base/file_constants.jl)
 
 ## Operations with File (fd) objects ##
 
diff --git a/base/initdefs.jl b/base/initdefs.jl
index 89fc88b0673a3..1988e56c6eb1d 100644
--- a/base/initdefs.jl
+++ b/base/initdefs.jl
@@ -93,7 +93,6 @@ function append_default_depot_path!(DEPOT_PATH)
     path in DEPOT_PATH || push!(DEPOT_PATH, path)
     path = abspath(Sys.BINDIR, "..", "share", "julia")
     path in DEPOT_PATH || push!(DEPOT_PATH, path)
-    return DEPOT_PATH
 end
 
 function init_depot_path()
@@ -112,7 +111,6 @@ function init_depot_path()
     else
         append_default_depot_path!(DEPOT_PATH)
     end
-    nothing
 end
 
 ## LOAD_PATH & ACTIVE_PROJECT ##
@@ -222,7 +220,9 @@ function parse_load_path(str::String)
 end
 
 function init_load_path()
-    if haskey(ENV, "JULIA_LOAD_PATH")
+    if Base.creating_sysimg
+        paths = ["@stdlib"]
+    elseif haskey(ENV, "JULIA_LOAD_PATH")
         paths = parse_load_path(ENV["JULIA_LOAD_PATH"])
     else
         paths = filter!(env -> env !== nothing,
diff --git a/base/libc.jl b/base/libc.jl
index a14920ec4f6b8..7d88e89bf605a 100644
--- a/base/libc.jl
+++ b/base/libc.jl
@@ -14,7 +14,7 @@ if Sys.iswindows()
     export GetLastError, FormatMessage
 end
 
-include("../errno_h.jl")
+include(string(length(Core.ARGS) >= 2 ? Core.ARGS[2] : "", "errno_h.jl"))  # include($BUILDROOT/base/errno_h.jl)
 
 ## RawFD ##
 
diff --git a/base/libuv.jl b/base/libuv.jl
index ea3d64072378f..64b228c6500e7 100644
--- a/base/libuv.jl
+++ b/base/libuv.jl
@@ -2,7 +2,7 @@
 
 # Core definitions for interacting with the libuv library from Julia
 
-include("../uv_constants.jl")
+include(string(length(Core.ARGS) >= 2 ? Core.ARGS[2] : "", "uv_constants.jl"))  # include($BUILDROOT/base/uv_constants.jl)
 
 # convert UV handle data to julia object, checking for null
 function uv_sizeof_handle(handle)
diff --git a/base/loading.jl b/base/loading.jl
index 79bc66fe456c3..f8100fc0915a2 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -42,7 +42,7 @@ elseif Sys.isapple()
     #    char filename[max_filename_length];
     # };
     # Buffer buf;
-    # getattrlist(path, &attr_list, &buf, sizeof(buf), FSOPT_NOFOLLOW);
+    # getattrpath(path, &attr_list, &buf, sizeof(buf), FSOPT_NOFOLLOW);
     function isfile_casesensitive(path)
         isaccessiblefile(path) || return false
         path_basename = String(basename(path))
@@ -813,7 +813,7 @@ end
 
 function find_source_file(path::AbstractString)
     (isabspath(path) || isfile(path)) && return path
-    base_path = joinpath(Sys.BINDIR, DATAROOTDIR, "julia", "src", "base", path)
+    base_path = joinpath(Sys.BINDIR, DATAROOTDIR, "julia", "base", path)
     return isfile(base_path) ? normpath(base_path) : nothing
 end
 
diff --git a/base/pcre.jl b/base/pcre.jl
index 963b3ee4726a2..d689e9be29113 100644
--- a/base/pcre.jl
+++ b/base/pcre.jl
@@ -6,7 +6,8 @@ module PCRE
 
 import ..RefValue
 
-include("../pcre_h.jl")
+# include($BUILDROOT/base/pcre_h.jl)
+include(string(length(Core.ARGS) >= 2 ? Core.ARGS[2] : "", "pcre_h.jl"))
 
 const PCRE_LIB = "libpcre2-8"
 
diff --git a/base/sysimg.jl b/base/sysimg.jl
index 175d26c3fee9b..5a14bf5bfd3b9 100644
--- a/base/sysimg.jl
+++ b/base/sysimg.jl
@@ -11,13 +11,14 @@ import Base.MainInclude: eval, include
 pushfirst!(Base._included_files, (@__MODULE__, joinpath(@__DIR__, "Base.jl")))
 pushfirst!(Base._included_files, (@__MODULE__, joinpath(@__DIR__, "sysimg.jl")))
 
+# set up depot & load paths to be able to find stdlib packages
+@eval Base creating_sysimg = true
+Base.init_depot_path()
+Base.init_load_path()
+
 if Base.is_primary_base_module
 # load some stdlib packages but don't put their names in Main
 let
-    # set up depot & load paths to be able to find stdlib packages
-    push!(empty!(LOAD_PATH), "@stdlib")
-    Base.append_default_depot_path!(DEPOT_PATH)
-
     # Stdlibs sorted in dependency, then alphabetical, order by contrib/print_sorted_stdlibs.jl
     # Run with the `--exclude-jlls` option to filter out all JLL packages
     stdlibs = [
diff --git a/doc/src/devdocs/build/distributing.md b/doc/src/devdocs/build/distributing.md
index 9ae75a8683020..c49f6f071224c 100644
--- a/doc/src/devdocs/build/distributing.md
+++ b/doc/src/devdocs/build/distributing.md
@@ -18,12 +18,12 @@ GPL licensed. We do hope to have a non-GPL distribution of Julia in the future.
 Versioning and Git
 ------------------
 The Makefile uses both the `VERSION` file and commit hashes and tags from the
-git repository to generate the `version_git.jl` with information we use to
+git repository to generate the `base/version_git.jl` with information we use to
 fill the splash screen and the `versioninfo()` output. If you for some reason
 don't want to have the git repository available when building you should
-pre-generate the `version_git.jl` file with:
+pregenerate the `base/version_git.jl` file with:
 
-    make -C base version_git.jl
+    make -C base version_git.jl.phony
 
 Julia has lots of build dependencies where we use patched versions that has not
 yet been included by the popular package managers. These dependencies will usually
diff --git a/src/base b/src/base
deleted file mode 120000
index 24312d19b81d4..0000000000000
--- a/src/base
+++ /dev/null
@@ -1 +0,0 @@
-../base
\ No newline at end of file
diff --git a/stdlib/Profile/src/Profile.jl b/stdlib/Profile/src/Profile.jl
index f260be3ae4dfe..705fcb6fa1dc5 100644
--- a/stdlib/Profile/src/Profile.jl
+++ b/stdlib/Profile/src/Profile.jl
@@ -521,7 +521,7 @@ function short_path(spath::Symbol, filenamecache::Dict{Symbol, String})
                 end
             end
             return path
-        elseif isfile(joinpath(Sys.BINDIR, Base.DATAROOTDIR, "julia", "src", "base", path))
+        elseif isfile(joinpath(Sys.BINDIR, Base.DATAROOTDIR, "julia", "base", path))
             # do the same mechanic for Base (or Core/Compiler) files as above,
             # but they start from a relative path
             return joinpath("@Base", normpath(path))
diff --git a/sysimage.mk b/sysimage.mk
index 8b7d19926f9da..2d154672d8130 100644
--- a/sysimage.mk
+++ b/sysimage.mk
@@ -20,51 +20,54 @@ $(build_private_libdir)/%.$(SHLIB_EXT): $(build_private_libdir)/%-o.a
 	@$(INSTALL_NAME_CMD)$(notdir $@) $@
 	@$(DSYMUTIL) $@
 
-BASE_DIR := $(build_datarootdir)/julia/src
-COMPILER_SRCS := $(addprefix $(BASE_DIR)/base/, \
-		boot.jl \
-		docs/core.jl \
-		abstractarray.jl \
-		abstractdict.jl \
-		array.jl \
-		bitarray.jl \
-		bitset.jl \
-		bool.jl \
-		ctypes.jl \
-		error.jl \
-		essentials.jl \
-		expr.jl \
-		generator.jl \
-		int.jl \
-		indices.jl \
-		iterators.jl \
-		namedtuple.jl \
-		number.jl \
-		operators.jl \
-		options.jl \
-		pair.jl \
-		pointer.jl \
-		promotion.jl \
-		range.jl \
-		reflection.jl \
-		traits.jl \
-		refvalue.jl \
-		tuple.jl)
-COMPILER_SRCS += $(shell find $(BASE_DIR)/base/compiler -name \*.jl)
-BASE_SRCS := $(shell find $(BASE_DIR) -name \*.jl -and -not -name sysimg.jl)
-STDLIB_SRCS := $(BASE_DIR)/base/sysimg.jl $(shell find $(build_datarootdir)/julia/stdlib/$(VERSDIR)/*/src -name \*.jl)
+COMPILER_SRCS := $(addprefix $(JULIAHOME)/, \
+		base/boot.jl \
+		base/docs/core.jl \
+		base/abstractarray.jl \
+		base/abstractdict.jl \
+		base/array.jl \
+		base/bitarray.jl \
+		base/bitset.jl \
+		base/bool.jl \
+		base/ctypes.jl \
+		base/error.jl \
+		base/essentials.jl \
+		base/expr.jl \
+		base/generator.jl \
+		base/int.jl \
+		base/indices.jl \
+		base/iterators.jl \
+		base/namedtuple.jl \
+		base/number.jl \
+		base/operators.jl \
+		base/options.jl \
+		base/pair.jl \
+		base/pointer.jl \
+		base/promotion.jl \
+		base/range.jl \
+		base/reflection.jl \
+		base/traits.jl \
+		base/refvalue.jl \
+		base/tuple.jl)
+COMPILER_SRCS += $(shell find $(JULIAHOME)/base/compiler -name \*.jl)
+# sort these to remove duplicates
+BASE_SRCS := $(sort $(shell find $(JULIAHOME)/base -name \*.jl -and -not -name sysimg.jl) \
+                    $(shell find $(BUILDROOT)/base -name \*.jl  -and -not -name sysimg.jl))
+STDLIB_SRCS := $(JULIAHOME)/base/sysimg.jl $(shell find $(build_datarootdir)/julia/stdlib/$(VERSDIR)/*/src -name \*.jl) \
+                    $(build_prefix)/manifest/Pkg
+RELBUILDROOT := $(call rel_path,$(JULIAHOME)/base,$(BUILDROOT)/base)/ # <-- make sure this always has a trailing slash
 
 $(build_private_libdir)/corecompiler.ji: $(COMPILER_SRCS)
-	@$(call PRINT_JULIA, cd $(BASE_DIR)/base && \
+	@$(call PRINT_JULIA, cd $(JULIAHOME)/base && \
 	$(call spawn,$(JULIA_EXECUTABLE)) -C "$(JULIA_CPU_TARGET)" --output-ji $(call cygpath_w,$@).tmp \
 		--startup-file=no --warn-overwrite=yes -g$(BOOTSTRAP_DEBUG_LEVEL) -O0 compiler/compiler.jl)
 	@mv $@.tmp $@
 
 $(build_private_libdir)/sys.ji: $(build_private_libdir)/corecompiler.ji $(JULIAHOME)/VERSION $(BASE_SRCS) $(STDLIB_SRCS)
-	@$(call PRINT_JULIA, cd $(BASE_DIR)/base && \
+	@$(call PRINT_JULIA, cd $(JULIAHOME)/base && \
 	if ! JULIA_BINDIR=$(call cygpath_w,$(build_bindir)) WINEPATH="$(call cygpath_w,$(build_bindir));$$WINEPATH" \
 			$(call spawn, $(JULIA_EXECUTABLE)) -g1 -O0 -C "$(JULIA_CPU_TARGET)" --output-ji $(call cygpath_w,$@).tmp $(JULIA_SYSIMG_BUILD_FLAGS) \
-			--startup-file=no --warn-overwrite=yes --sysimage $(call cygpath_w,$<) sysimg.jl; then \
+			--startup-file=no --warn-overwrite=yes --sysimage $(call cygpath_w,$<) sysimg.jl $(RELBUILDROOT); then \
 		echo '*** This error might be fixed by running `make clean`. If the error persists$(COMMA) try `make cleanall`. ***'; \
 		false; \
 	fi )
@@ -72,7 +75,7 @@ $(build_private_libdir)/sys.ji: $(build_private_libdir)/corecompiler.ji $(JULIAH
 
 define sysimg_builder
 $$(build_private_libdir)/sys$1-o.a $$(build_private_libdir)/sys$1-bc.a : $$(build_private_libdir)/sys$1-%.a : $$(build_private_libdir)/sys.ji
-	@$$(call PRINT_JULIA, cd $$(BASE_DIR)/base && \
+	@$$(call PRINT_JULIA, cd $$(JULIAHOME)/base && \
 	if ! JULIA_BINDIR=$$(call cygpath_w,$(build_bindir)) WINEPATH="$$(call cygpath_w,$$(build_bindir));$$$$WINEPATH" \
 			JULIA_NUM_THREADS=1 \
 			$$(call spawn, $3) $2 -C "$$(JULIA_CPU_TARGET)" --output-$$* $$(call cygpath_w,$$@).tmp $$(JULIA_SYSIMG_BUILD_FLAGS) \