diff --git a/mozilla/security/coreconf/Linux.mk b/mozilla/security/coreconf/Linux.mk
index 88ad32a8627..6a65038f060 100644
--- a/mozilla/security/coreconf/Linux.mk
+++ b/mozilla/security/coreconf/Linux.mk
@@ -172,3 +172,6 @@ G++INCLUDES		= -I/usr/include/g++
 # Always set CPU_TAG on Linux, OpenVMS, WINCE.
 #
 CPU_TAG = _$(CPU_ARCH)
+
+USE_SYSTEM_ZLIB = 1
+ZLIB_LIBS = -lz
diff --git a/mozilla/security/nss/cmd/Makefile b/mozilla/security/nss/cmd/Makefile
index 8e8342fd536..5369d890449 100644
--- a/mozilla/security/nss/cmd/Makefile
+++ b/mozilla/security/nss/cmd/Makefile
@@ -42,6 +42,10 @@ DEPTH = ../..
 include manifest.mn
 include $(CORE_DEPTH)/coreconf/config.mk
 
+ifndef USE_SYSTEM_ZLIB
+ZLIB_SRCDIR = zlib  # Add the zlib directory to DIRS.
+endif
+
 # These sources were once in this directory, but now are gone.
 MISSING_SOURCES = \
 	addcert.c \
diff --git a/mozilla/security/nss/cmd/manifest.mn b/mozilla/security/nss/cmd/manifest.mn
index de58f84c1b0..352872ad7a9 100644
--- a/mozilla/security/nss/cmd/manifest.mn
+++ b/mozilla/security/nss/cmd/manifest.mn
@@ -41,7 +41,7 @@ DEPTH	= ../..
 REQUIRES = nss nspr libdbm
 
 DIRS = lib  \
- zlib \
+ $(ZLIB_SRCDIR) \
  addbuiltin \
  atob  \
  bltest \
diff --git a/mozilla/security/nss/cmd/platlibs.mk b/mozilla/security/nss/cmd/platlibs.mk
index b2d761c5add..cecd8aa02f2 100644
--- a/mozilla/security/nss/cmd/platlibs.mk
+++ b/mozilla/security/nss/cmd/platlibs.mk
@@ -82,10 +82,6 @@ EXTRA_LIBS += \
 	wsock32.lib \
 	winmm.lib \
 	$(NULL)
-
-JAR_LIBS = $(DIST)/lib/$(LIB_PREFIX)jar.$(LIB_SUFFIX) \
-	$(DIST)/lib/$(LIB_PREFIX)zlib.$(LIB_SUFFIX) \
-	$(NULL)
 else
 
 # $(PROGRAM) has explicit dependencies on $(EXTRA_LIBS)
@@ -144,10 +140,6 @@ EXTRA_SHARED_LIBS += \
 endif
 endif
 
-JAR_LIBS = $(DIST)/lib/$(LIB_PREFIX)jar.$(LIB_SUFFIX) \
-	$(DIST)/lib/$(LIB_PREFIX)zlib.$(LIB_SUFFIX) \
-	$(NULL)
-
 else # USE_STATIC_LIBS
 # can't do this in manifest.mn because OS_ARCH isn't defined there.
 ifeq ($(OS_ARCH), WINNT)
@@ -168,10 +160,6 @@ EXTRA_LIBS += \
 	wsock32.lib \
 	winmm.lib \
 	$(NULL)
-
-JAR_LIBS = $(DIST)/lib/$(LIB_PREFIX)jar.$(LIB_SUFFIX) \
-	$(DIST)/lib/$(LIB_PREFIX)zlib.$(LIB_SUFFIX) \
-	$(NULL)
 else
 
 # $(PROGRAM) has explicit dependencies on $(EXTRA_LIBS)
@@ -227,10 +215,17 @@ EXTRA_SHARED_LIBS += \
 	-lplds4 \
 	-lnspr4 \
 	$(NULL)
-
-JAR_LIBS = $(DIST)/lib/$(LIB_PREFIX)jar.$(LIB_SUFFIX) \
-	$(DIST)/lib/$(LIB_PREFIX)zlib.$(LIB_SUFFIX) \
-	$(NULL)
 endif
 
 endif # USE_STATIC_LIBS
+
+# If a platform has a system zlib, set USE_SYSTEM_ZLIB to 1 and
+# ZLIB_LIBS to the linker command-line arguments for the system zlib
+# (for example, -lz) in the platform's config file in coreconf.
+ifndef USE_SYSTEM_ZLIB
+ZLIB_LIBS = $(DIST)/lib/$(LIB_PREFIX)zlib.$(LIB_SUFFIX)
+endif
+
+JAR_LIBS = $(DIST)/lib/$(LIB_PREFIX)jar.$(LIB_SUFFIX) \
+	$(ZLIB_LIBS) \
+	$(NULL)