diff --git a/ChangeLog b/ChangeLog
index 45e4b85bbc..dd04b1d639 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -38,6 +38,11 @@ Changes
    * Improve the documentation of mbedtls_net_accept(). Contributed by Ivan Krylov.
    * Improve the documentation of mbedtls_ssl_write(). Suggested by
      Paul Sokolovsky in #1356.
+   * Add an option in the makefile to support ar utilities where the operation
+     letter must not be prefixed by '-', such as LLVM. Found and fixed by
+     Alex Hixon.
+   * Allow configuring the shared library extension by setting the DLEXT
+     environment variable when using the project makefiles.
 
 = mbed TLS 2.1.11 branch released 2018-03-16
 
diff --git a/library/Makefile b/library/Makefile
index 8e651f54e4..9e2d7d6a74 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -35,9 +35,12 @@ SOEXT_TLS=so.10
 SOEXT_X509=so.0
 SOEXT_CRYPTO=so.0
 
-DLEXT=so
-# OSX shared library extension:
-# DLEXT=dylib
+# Set DLEXT=dylib to compile as a shared library for Mac OS X
+DLEXT ?= so
+
+# Set AR_DASH= (empty string) to use an ar implentation that does not accept
+# the - prefix for command line options (e.g. llvm-ar)
+AR_DASH ?= -
 
 # Windows shared library extension:
 ifdef WINDOWS_BUILD
@@ -89,9 +92,9 @@ shared: libmbedcrypto.$(DLEXT) libmbedx509.$(DLEXT) libmbedtls.$(DLEXT)
 # tls
 libmbedtls.a: $(OBJS_TLS)
 	echo "  AR    $@"
-	$(AR) -rc $@ $(OBJS_TLS)
+	$(AR) $(AR_DASH)rc $@ $(OBJS_TLS)
 	echo "  RL    $@"
-	$(AR) -s $@
+	$(AR) $(AR_DASH)s $@
 
 libmbedtls.$(SOEXT_TLS): $(OBJS_TLS) libmbedx509.so
 	echo "  LD    $@"
@@ -112,9 +115,9 @@ libmbedtls.dll: $(OBJS_TLS) libmbedx509.dll
 # x509
 libmbedx509.a: $(OBJS_X509)
 	echo "  AR    $@"
-	$(AR) -rc $@ $(OBJS_X509)
+	$(AR) $(AR_DASH)rc $@ $(OBJS_X509)
 	echo "  RL    $@"
-	$(AR) -s $@
+	$(AR) $(AR_DASH)s $@
 
 libmbedx509.$(SOEXT_X509): $(OBJS_X509) libmbedcrypto.so
 	echo "  LD    $@"
@@ -135,9 +138,9 @@ libmbedx509.dll: $(OBJS_X509) libmbedcrypto.dll
 # crypto
 libmbedcrypto.a: $(OBJS_CRYPTO)
 	echo "  AR    $@"
-	$(AR) -rc $@ $(OBJS_CRYPTO)
+	$(AR) $(AR_DASH)rc $@ $(OBJS_CRYPTO)
 	echo "  RL    $@"
-	$(AR) -s $@
+	$(AR) $(AR_DASH)s $@
 
 libmbedcrypto.$(SOEXT_CRYPTO): $(OBJS_CRYPTO)
 	echo "  LD    $@"
diff --git a/programs/Makefile b/programs/Makefile
index 544a2d8f99..db85eee0bf 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -35,7 +35,7 @@ ifdef SHARED
 SHARED_SUFFIX=.$(DLEXT)
 endif
 else
-DLEXT=so
+DLEXT ?= so
 EXEXT=
 SHARED_SUFFIX=
 endif
diff --git a/tests/Makefile b/tests/Makefile
index e97887ae16..40e65fab09 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -35,7 +35,7 @@ ifdef SHARED
 SHARED_SUFFIX=.$(DLEXT)
 endif
 else
-DLEXT=so
+DLEXT ?= so
 EXEXT=
 SHARED_SUFFIX=
 endif
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index b91355d303..5b55faccd4 100644
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -11,6 +11,7 @@ die "$0: no test suite found\n" unless @suites;
 
 # in case test suites are linked dynamically
 $ENV{'LD_LIBRARY_PATH'} = '../library';
+$ENV{'DYLD_LIBRARY_PATH'} = '../library';
 
 my $prefix = $^O eq "MSWin32" ? '' : './';