diff --git a/Makefile.COMMON b/Makefile.COMMON
index d2302dc..f8aa1b3 100644
--- a/Makefile.COMMON
+++ b/Makefile.COMMON
@@ -41,27 +41,37 @@ VERSION ?= $(error VERSION not set in including Makefile)
 TARGET  ?= $(error TARGET not set in including Makefile)
 
 SRC    ?= $(shell find . -type f -name "*.go" ! -path "./.build/*")
-GOOS   := $(shell uname | tr A-Z a-z)
-GOARCH := $(subst x86_64,amd64,$(patsubst i%86,386,$(shell uname -m)))
+GOOS   ?= $(shell uname | tr A-Z a-z)
+GOARCH ?= $(subst x86_64,amd64,$(patsubst i%86,386,$(shell uname -m)))
 
-ifeq ($(GOOS),darwin)
-	RELEASE_SUFFIX ?= -osx$(shell sw_vers -productVersion)
-endif
+GO_VERSION ?= 1.5.3
 
-GO_VERSION ?= 1.4.2
-
-ifeq ($(shell type go >/dev/null && go version | sed 's/.*go\([0-9.]*\).*/\1/'), $(GO_VERSION))
-	GOROOT := $(shell go env GOROOT)
+# Check for the correct version of go in the path. If we find it, use it.
+# Otherwise, prepare to build go locally.
+ifeq ($(shell command -v "go" >/dev/null && go version | sed -e 's/^[^0-9.]*\([0-9.]*\).*/\1/'), $(GO_VERSION))
+	GOCC   ?= $(shell command -v "go")
+	GOFMT  ?= $(shell command -v "gofmt")
+	GO     ?= $(GOCC)
 else
-	GOROOT := $(CURDIR)/.build/go$(GO_VERSION)
+	GOURL  ?= https://golang.org/dl
+	GOPKG  ?= go$(GO_VERSION).$(GOOS)-$(GOARCH).tar.gz
+	GOROOT ?= $(CURDIR)/.build/go$(GO_VERSION)
+	GOCC   ?= $(GOROOT)/bin/go
+	GOFMT  ?= $(GOROOT)/bin/gofmt
+	GO     ?= GOROOT=$(GOROOT) $(GOCC)
 endif
 
-GOURL      ?= https://golang.org/dl
-GOPKG      ?= go$(GO_VERSION).$(GOOS)-$(GOARCH)$(RELEASE_SUFFIX).tar.gz
-GOPATH     := $(CURDIR)/.build/gopath
-GOCC       ?= $(GOROOT)/bin/go
-GO         ?= GOROOT=$(GOROOT) GOPATH=$(GOPATH) $(GOCC)
-GOFMT      ?= $(GOROOT)/bin/gofmt
+# Use vendored dependencies if available. Otherwise try to download them.
+ifneq (,$(wildcard vendor))
+	DEPENDENCIES := $(shell find vendor/ -type f -iname '*.go')
+	GO           := GO15VENDOREXPERIMENT=1 $(GO)
+else
+	GOPATH       := $(CURDIR)/.build/gopath
+	ROOTPKG      ?= github.com/prometheus/$(TARGET)
+	SELFLINK     ?= $(GOPATH)/src/$(ROOTPKG)
+	DEPENDENCIES := dependencies-stamp
+	GO           := GOPATH=$(GOPATH) $(GO)
+endif
 
 # Never honor GOBIN, should it be set at all.
 unexport GOBIN
@@ -69,29 +79,10 @@ unexport GOBIN
 SUFFIX   ?= $(GOOS)-$(GOARCH)
 BINARY   ?= $(TARGET)
 ARCHIVE  ?= $(TARGET)-$(VERSION).$(SUFFIX).tar.gz
-ROOTPKG  ?= github.com/prometheus/$(TARGET)
-SELFLINK ?= $(GOPATH)/src/$(ROOTPKG)
 
 default: $(BINARY)
 
-$(GOCC):
-	@echo Go version $(GO_VERSION) required but not found in PATH.
-	@echo About to download and install go$(GO_VERSION) to $(GOROOT)
-	@echo Abort now if you want to manually install it system-wide instead.
-	@echo
-	@sleep 5
-	mkdir -p $(GOROOT)
-	curl -L $(GOURL)/$(GOPKG) | tar -C $(GOROOT) --strip 1 -xz
-
-$(SELFLINK):
-	mkdir -p $(dir $@)
-	ln -s $(CURDIR) $@
-
-dependencies-stamp: $(GOCC) $(SRC) | $(SELFLINK)
-	$(GO) get -d
-	touch $@
-
-$(BINARY): $(GOCC) $(SRC) dependencies-stamp Makefile Makefile.COMMON
+$(BINARY): $(GOCC) $(SRC) $(DEPENDENCIES) Makefile Makefile.COMMON
 	$(GO) build $(GOFLAGS) -o $@
 
 .PHONY: archive
@@ -106,14 +97,36 @@ tag:
 	git push --tags
 
 .PHONY: test
-test: $(GOCC) dependencies-stamp
-	$(GO) test ./...
+test: $(GOCC) $(DEPENDENCIES)
+	$(GO) test $$($(GO) list ./... | grep -v /vendor/)
 
 .PHONY: format
 format: $(GOCC)
-	find . -iname '*.go' | egrep -v "^\./\.build|./generated|\./Godeps|\.(l|y)\.go" | xargs -n1 $(GOFMT) -w -s=true
+	find . -iname '*.go' | egrep -v "^\./\.build|./generated|\./vendor|\.(l|y)\.go" | xargs -n1 $(GOFMT) -w -s=true
 
 .PHONY: clean
 clean:
 	rm -rf $(BINARY) $(ARCHIVE) .build *-stamp
 
+
+
+$(GOCC):
+	@echo Go version $(GO_VERSION) required but not found in PATH.
+	@echo About to download and install go$(GO_VERSION) to $(GOROOT)
+	@echo Abort now if you want to manually install it system-wide instead.
+	@echo
+	@sleep 5
+	mkdir -p .build
+	# The archive contains a single directory called 'go/'.
+	curl -L $(GOURL)/$(GOPKG) | tar -C .build -xzf -
+	rm -rf $(GOROOT)
+	mv .build/go $(GOROOT)
+
+$(SELFLINK):
+	mkdir -p $(dir $@)
+	ln -s $(CURDIR) $@
+
+# Download dependencies if project doesn't vendor them.
+dependencies-stamp: $(GOCC) $(SRC) | $(SELFLINK)
+	$(GO) get -d
+	touch $@