diff --git a/third_party/nlbuild-autotools/repo/.default-version b/third_party/nlbuild-autotools/repo/.default-version
index 9f05f9f2c..ec70f7556 100644
--- a/third_party/nlbuild-autotools/repo/.default-version
+++ b/third_party/nlbuild-autotools/repo/.default-version
@@ -1 +1 @@
-1.6.5
+1.6.6
diff --git a/third_party/nlbuild-autotools/repo/CHANGES b/third_party/nlbuild-autotools/repo/CHANGES
index 516c8f187..6bd89216f 100644
--- a/third_party/nlbuild-autotools/repo/CHANGES
+++ b/third_party/nlbuild-autotools/repo/CHANGES
@@ -1,3 +1,9 @@
+1.6.6 (2019-04-09)
+
+        * Added code coverage support for clang, which uses a link flag
+          --coverage instead of linking to a library(-lgov) as gcc does
+          for code coverage functions.
+
 1.6.5 (2018-11-19)
 
         * Addressed an issue in which the failure to make the 'repos-warning'
diff --git a/third_party/nlbuild-autotools/repo/autoconf/m4/nl_enable_coverage.m4 b/third_party/nlbuild-autotools/repo/autoconf/m4/nl_enable_coverage.m4
index b60c4bb0d..7a62a5359 100644
--- a/third_party/nlbuild-autotools/repo/autoconf/m4/nl_enable_coverage.m4
+++ b/third_party/nlbuild-autotools/repo/autoconf/m4/nl_enable_coverage.m4
@@ -58,7 +58,7 @@ AC_DEFUN([NL_ENABLE_COVERAGE],
             AC_ARG_ENABLE(coverage,
                 [AS_HELP_STRING([--enable-coverage],[Enable the generation of code-coverage instances @<:@default=$1@:>@.])],
                 [
-                    case "${enableval}" in 
+                    case "${enableval}" in
 
                     no|yes)
                         nl_cv_build_coverage=${enableval}
@@ -78,21 +78,23 @@ AC_DEFUN([NL_ENABLE_COVERAGE],
                     if test "${nl_cv_build_optimized}" = "yes"; then
                         AC_MSG_WARN([--enable-optimization was specified, coverage disabled])
                         nl_cv_build_coverage=no
-            
+
                     else
                         nl_cv_build_coverage=$1
-            
+
                     fi
                 ])
 
-            if test "${nl_cv_build_coverage}" = "yes"; then         
+            if test "${nl_cv_build_coverage}" = "yes"; then
                 if test "${GCC}" != "yes"; then
                     AC_MSG_ERROR([GCC or a GCC-compatible toolchain is required for --enable-coverage])
-
                 else
                     NL_COVERAGE_CPPFLAGS="--coverage"
-                    NL_COVERAGE_LIBS="-lgcov"
-
+                    if ${CC} --version | grep -q clang; then
+                        NL_COVERAGE_LDFLAGS="--coverage"
+                    else
+                        NL_COVERAGE_LIBS="-lgcov"
+                    fi
                 fi
             fi
     ])
diff --git a/third_party/nlbuild-autotools/repo/examples/configure.ac b/third_party/nlbuild-autotools/repo/examples/configure.ac
index 02bc83d96..4de427008 100644
--- a/third_party/nlbuild-autotools/repo/examples/configure.ac
+++ b/third_party/nlbuild-autotools/repo/examples/configure.ac
@@ -292,14 +292,14 @@ AC_PATH_PROG([PKG_CONFIG],[pkg-config])
 # 	    # configured nor built, so the normal checks we undertake for an
 # 	    # external package cannot be run here. Simply set the appropriate
 # 	    # variables and trust all will be well.
-# 
+#
 #             NLUNIT_TEST_CPPFLAGS="-I\${abs_top_srcdir}/third_party/nlunit-test/repo/src"
 #             NLUNIT_TEST_LDFLAGS="-L${ac_pwd}/third_party/nlunit-test/repo/src"
 #             NLUNIT_TEST_LIBS="-lnlunit-test"
 #         ],
 #         [
 #             # Check for required nlunit-test headers.
-# 
+#
 #             AC_CHECK_HEADERS([nlunit-test.h],
 #             [],
 #             [
@@ -312,7 +312,7 @@ AC_PATH_PROG([PKG_CONFIG],[pkg-config])
 # # location, its directory stem within this package needs to be set
 # # accordingly. In addition, if the location is internal, then we need
 # # to attempt to pull it down using the bootstrap makefile.
-# 
+#
 # if test "${nl_with_nlunit_test}" = "internal"; then
 #     maybe_nlunit_test_dirstem="nlunit-test/repo"
 #     nlunit_test_dirstem="third_party/${maybe_nlunit_test_dirstem}"
@@ -364,7 +364,7 @@ fi
 # this, as needed.
 
 # # Add any nlunit-test CPPFLAGS, LDFLAGS, and LIBS
-# 
+#
 # CPPFLAGS="${CPPFLAGS} ${NLUNIT_TEST_CPPFLAGS}"
 # LDFLAGS="${LDFLAGS} ${NLUNIT_TEST_LDFLAGS}"
 # LIBS="${LIBS} ${NLUNIT_TEST_LIBS}"
@@ -373,6 +373,7 @@ fi
 
 CPPFLAGS="${CPPFLAGS} ${NL_COVERAGE_CPPFLAGS}"
 LIBS="${LIBS} ${NL_COVERAGE_LIBS}"
+LDFLAGS="${LDFLAGS} ${NL_COVERAGE_LDFLAGS}"
 
 # At this point, we can restore the compiler flags to whatever the
 # user passed in, now that we're clear of any -Werror issues by