diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..d25c9a6
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "crypto"]
+	path = crypto
+	url = git@github.com:ARMmbed/mbedtls-psa.git
+	branch = feature-psa
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 99bf31f..19ab4eb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,6 +9,7 @@
 option(ENABLE_ZLIB_SUPPORT "Build mbed TLS with zlib library." OFF)
 
 option(ENABLE_PROGRAMS "Build mbed TLS programs." ON)
+option(USE_CRYPTO_SUBMODULE "Build and use libmbedcrypto from the crypto submodule." OFF)
 
 option(UNSAFE_BUILD "Allow unsafe builds. These builds ARE NOT SECURE." OFF)
 
@@ -167,8 +168,6 @@
     set(LIB_INSTALL_DIR lib)
 endif()
 
-include_directories(include/)
-
 if(ENABLE_ZLIB_SUPPORT)
     find_package(ZLIB)
 
@@ -179,6 +178,10 @@
 
 add_subdirectory(library)
 add_subdirectory(include)
+if(USE_CRYPTO_SUBMODULE)
+    add_subdirectory(crypto/library)
+    add_subdirectory(crypto/include)
+endif()
 
 if(ENABLE_PROGRAMS)
     add_subdirectory(programs)
diff --git a/ChangeLog b/ChangeLog
index 8f0e8c1..d387815 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS x.xx.x branch released xxxx-xx-xx
+
+Features
+   * Add an experimental build option, USE_CRYPTO_SUBMODULE, to enable use of
+     Mbed Crypto as the source of the cryptography implementation.
+   * Add an experimental configuration option, MBEDTLS_PSA_CRYPTO_C, to enable
+     the PSA Crypto API from Mbed Crypto when additionally used with the
+     USE_CRYPTO_SUBMODULE build option.
+
 = mbed TLS 2.14.0 branch released 2018-11-19
 
 Security
diff --git a/Makefile b/Makefile
index f4c0a00..87b5a0c 100644
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,13 @@
 	mkdir -p $(DESTDIR)/lib
 	cp -RP library/libmbedtls.*    $(DESTDIR)/lib
 	cp -RP library/libmbedx509.*   $(DESTDIR)/lib
+ifdef USE_CRYPTO_SUBMODULE
+	mkdir -p $(DESTDIR)/include/psa
+	cp -rp crypto/include/psa $(DESTDIR)/include
+	cp -RP crypto/library/libmbedcrypto.* $(DESTDIR)/lib
+else
 	cp -RP library/libmbedcrypto.* $(DESTDIR)/lib
+endif
 
 	mkdir -p $(DESTDIR)/bin
 	for p in programs/*/* ; do              \
@@ -44,6 +50,9 @@
 	rm -f $(DESTDIR)/lib/libmbedtls.*
 	rm -f $(DESTDIR)/lib/libmbedx509.*
 	rm -f $(DESTDIR)/lib/libmbedcrypto.*
+ifdef USE_CRYPTO_SUBMODULE
+	$(MAKE) -C crypto uninstall
+endif
 
 	for p in programs/*/* ; do              \
 	    if [ -x $$p ] && [ ! -d $$p ] ;     \
@@ -85,6 +94,9 @@
 	$(MAKE) -C library clean
 	$(MAKE) -C programs clean
 	$(MAKE) -C tests clean
+ifdef USE_CRYPTO_SUBMODULE
+	$(MAKE) -C crypto clean
+endif
 ifndef WINDOWS
 	find . \( -name \*.gcno -o -name \*.gcda -o -name \*.info \) -exec rm {} +
 endif
diff --git a/README.md b/README.md
index d7a0e9d..58e5273 100644
--- a/README.md
+++ b/README.md
@@ -158,6 +158,43 @@
 
 We provide some non-standard configurations focused on specific use cases in the `configs/` directory. You can read more about those in `configs/README.txt`
 
+Using Mbed Crypto as a submodule
+--------------------------------
+
+As an experimental feature, you can use Mbed Crypto as the source of the cryptography implementation, with Mbed TLS providing the X.509 and TLS parts of the library. Mbed Crypto is currently provided for evaluation only and should not be used in production. At this point, you should only use this option if you want to try out the experimental PSA Crypto API.
+
+To enable the use of Mbed Crypto as a submodule:
+
+1. Check out the `crypto` submodule and update it.
+
+        git submodule init crypto
+        git submodule update crypto
+
+2. (Optional) TO enable the PSA Crypto API, set the build configuration option `MBEDTLS_PSA_CRYPTO_C`. You can either edit `include/mbedtls/config.h` directly or use the configuration script:
+
+        scripts/config.pl set MBEDTLS_PSA_CRYPTO_C
+
+3. Activate the build option `USE_CRYPTO_SUBMODULE`. With GNU make, set `USE_CRYPTO_SUBMODULE=1` on each make invocation:
+
+        make USE_CRYPTO_SUBMODULE=1
+        make USE_CRYPTO_SUBMODULE=1 test
+        tests/ssl-opt.sh -f Default
+
+   Note that you need to pass `USE_CRYPTO_SUBMODULE=1` even to `make clean`. For example, if you change `config.h`, run this before rebuilding:
+
+        make USE_CRYPTO_SUBMODULE=1 clean
+
+   With CMake, create a build directory (recommended) and pass `-DUSE_CRYPTO_SUBMODULE=1` to `cmake`:
+
+        mkdir build
+        cd build
+        cmake -DUSE_CRYPTO_SUBMODULE=1 ..
+        make
+        make test
+        tests/ssl-opt.sh -f Default
+
+Note that this does not enable the PSA-specific tests and utility programs. To use these programs, use Mbed Crypto as a standalone project.
+
 Porting Mbed TLS
 ----------------
 
diff --git a/crypto b/crypto
new file mode 160000
index 0000000..dbb83ac
--- /dev/null
+++ b/crypto
@@ -0,0 +1 @@
+Subproject commit dbb83ac5f7b96077b21fc9fe72b2687986acf963
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 425e3ea..a41277f 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -496,6 +496,12 @@
 #error "MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO and MBEDTLS_PLATFORM_STD_NV_SEED_WRITE cannot be defined simultaneously"
 #endif
 
+#if defined(MBEDTLS_PSA_CRYPTO_C) &&            \
+    !( defined(MBEDTLS_CTR_DRBG_C) &&           \
+       defined(MBEDTLS_ENTROPY_C) )
+#error "MBEDTLS_PSA_CRYPTO_C defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_RSA_C) && ( !defined(MBEDTLS_BIGNUM_C) ||         \
     !defined(MBEDTLS_OID_C) )
 #error "MBEDTLS_RSA_C defined, but not all prerequisites"
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 16ed503..0242bd8 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2591,6 +2591,25 @@
 #define MBEDTLS_POLY1305_C
 
 /**
+ * \def MBEDTLS_PSA_CRYPTO_C
+ *
+ * Enable the Platform Security Architecture cryptography API.
+ *
+ * \note This option only has an effect when the build option
+ * USE_CRYPTO_SUBMODULE is also in use.
+ *
+ * \warning This feature is experimental and available on an opt-in basis only.
+ * PSA APIs are subject to change at any time. The implementation comes with
+ * less assurance and support than the rest of Mbed TLS.
+ *
+ * Module:  crypto/library/psa_crypto.c
+ *
+ * Requires: MBEDTLS_CTR_DRBG_C, MBEDTLS_ENTROPY_C
+ *
+ */
+//#define MBEDTLS_PSA_CRYPTO_C
+
+/**
  * \def MBEDTLS_RIPEMD160_C
  *
  * Enable the RIPEMD-160 hash algorithm.
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index ea51363..cab8c27 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -140,42 +140,80 @@
 endif()
 
 if(USE_STATIC_MBEDTLS_LIBRARY)
-    add_library(${mbedcrypto_static_target} STATIC ${src_crypto})
-    set_target_properties(${mbedcrypto_static_target} PROPERTIES OUTPUT_NAME mbedcrypto)
-    target_link_libraries(${mbedcrypto_static_target} ${libs})
+    if(NOT USE_CRYPTO_SUBMODULE)
+        add_library(${mbedcrypto_static_target} STATIC ${src_crypto})
+        set_target_properties(${mbedcrypto_static_target} PROPERTIES OUTPUT_NAME mbedcrypto)
+        target_link_libraries(${mbedcrypto_static_target} ${libs})
+        target_include_directories(${mbedcrypto_static_target} PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    endif()
 
     add_library(${mbedx509_static_target} STATIC ${src_x509})
     set_target_properties(${mbedx509_static_target} PROPERTIES OUTPUT_NAME mbedx509)
     target_link_libraries(${mbedx509_static_target} ${libs} ${mbedcrypto_static_target})
+    target_include_directories(${mbedx509_static_target}
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
     add_library(${mbedtls_static_target} STATIC ${src_tls})
     set_target_properties(${mbedtls_static_target} PROPERTIES OUTPUT_NAME mbedtls)
     target_link_libraries(${mbedtls_static_target} ${libs} ${mbedx509_static_target})
+    target_include_directories(${mbedtls_static_target}
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/
+        )
 
-    install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        install(TARGETS ${mbedtls_static_target} ${mbedx509_static_target} ${mbedcrypto_static_target}
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_STATIC_MBEDTLS_LIBRARY)
 
 if(USE_SHARED_MBEDTLS_LIBRARY)
-    add_library(mbedcrypto SHARED ${src_crypto})
-    set_target_properties(mbedcrypto PROPERTIES VERSION 2.14.0 SOVERSION 3)
-    target_link_libraries(mbedcrypto ${libs})
+    if(NOT USE_CRYPTO_SUBMODULE)
+        add_library(mbedcrypto SHARED ${src_crypto})
+        set_target_properties(mbedcrypto PROPERTIES VERSION 2.14.0 SOVERSION 3)
+        target_link_libraries(mbedcrypto ${libs})
+        target_include_directories(mbedcrypto PUBLIC ${CMAKE_SOURCE_DIR}/include/)
+    endif()
 
     add_library(mbedx509 SHARED ${src_x509})
     set_target_properties(mbedx509 PROPERTIES VERSION 2.14.0 SOVERSION 0)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
+    target_include_directories(mbedx509
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
     add_library(mbedtls SHARED ${src_tls})
     set_target_properties(mbedtls PROPERTIES VERSION 2.14.0 SOVERSION 12)
     target_link_libraries(mbedtls ${libs} mbedx509)
+    target_include_directories(mbedtls
+        PUBLIC ${CMAKE_SOURCE_DIR}/include/
+        PUBLIC ${CMAKE_SOURCE_DIR}/crypto/include/)
 
-    install(TARGETS mbedtls mbedx509 mbedcrypto
-            DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    if(USE_CRYPTO_SUBMODULE)
+        install(TARGETS mbedtls mbedx509
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    else()
+        install(TARGETS mbedtls mbedx509 mbedcrypto
+                DESTINATION ${LIB_INSTALL_DIR}
+                PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+    endif()
 endif(USE_SHARED_MBEDTLS_LIBRARY)
 
-add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
-if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
-    add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+if(USE_CRYPTO_SUBMODULE)
+    add_custom_target(lib DEPENDS mbedx509 mbedtls)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(lib mbedx509_static mbedtls_static)
+    endif()
+else()
+    add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)
+    if(USE_STATIC_MBEDTLS_LIBRARY AND USE_SHARED_MBEDTLS_LIBRARY)
+        add_dependencies(lib mbedcrypto_static mbedx509_static mbedtls_static)
+    endif()
 endif()
diff --git a/library/Makefile b/library/Makefile
index 430c598..f01b1a1 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -63,6 +63,13 @@
 endif
 endif
 
+
+ifdef USE_CRYPTO_SUBMODULE
+# Look in crypto for libmbedcrypto.
+LOCAL_LDFLAGS += -L../crypto/library
+LOCAL_CFLAGS += -I../crypto/include
+CRYPTO := ../crypto/library/
+else
 OBJS_CRYPTO=	aes.o		aesni.o		arc4.o		\
 		aria.o		asn1parse.o	asn1write.o	\
 		base64.o	bignum.o	blowfish.o	\
@@ -85,6 +92,8 @@
 		sha1.o		sha256.o	sha512.o	\
 		threading.o	timing.o	version.o	\
 		version_features.o		xtea.o
+CRYPTO :=
+endif
 
 OBJS_X509=	certs.o		pkcs11.o	x509.o		\
 		x509_create.o	x509_crl.o	x509_crt.o	\
@@ -148,7 +157,7 @@
 endif
 endif
 
-libmbedx509.$(SOEXT_X509): $(OBJS_X509) libmbedcrypto.so
+libmbedx509.$(SOEXT_X509): $(OBJS_X509) $(CRYPTO)libmbedcrypto.so
 	echo "  LD    $@"
 	$(CC) -shared -Wl,-soname,$@ -L. -lmbedcrypto $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@ $(OBJS_X509)
 
@@ -165,6 +174,10 @@
 	$(CC) -shared -Wl,-soname,$@ -Wl,--out-implib,$@.a -o $@ $(OBJS_X509) -lws2_32 -lwinmm -lgdi32 -L. -lmbedcrypto -static-libgcc $(LOCAL_LDFLAGS) $(LDFLAGS)
 
 # crypto
+ifdef USE_CRYPTO_SUBMODULE
+libmbedcrypto.%:
+	$(MAKE) CRYPTO_INCLUDES:="-I../../include -I../include" -C ../crypto/library $@
+else
 libmbedcrypto.a: $(OBJS_CRYPTO)
 	echo "  AR    $@"
 	$(AR) $(ARFLAGS) $@ $(OBJS_CRYPTO)
@@ -190,6 +203,7 @@
 libmbedcrypto.dll: $(OBJS_CRYPTO)
 	echo "  LD    $@"
 	$(CC) -shared -Wl,-soname,$@ -Wl,--out-implib,$@.a -o $@ $(OBJS_CRYPTO) -lws2_32 -lwinmm -lgdi32 -static-libgcc $(LOCAL_LDFLAGS) $(LDFLAGS)
+endif
 
 .c.o:
 	echo "  CC    $<"
diff --git a/library/version_features.c b/library/version_features.c
index f1798a7..53cf0a5 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -681,6 +681,9 @@
 #if defined(MBEDTLS_POLY1305_C)
     "MBEDTLS_POLY1305_C",
 #endif /* MBEDTLS_POLY1305_C */
+#if defined(MBEDTLS_PSA_CRYPTO_C)
+    "MBEDTLS_PSA_CRYPTO_C",
+#endif /* MBEDTLS_PSA_CRYPTO_C */
 #if defined(MBEDTLS_RIPEMD160_C)
     "MBEDTLS_RIPEMD160_C",
 #endif /* MBEDTLS_RIPEMD160_C */
diff --git a/programs/Makefile b/programs/Makefile
index b6d1fa2..d379ddf 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -14,6 +14,10 @@
 		-lmbedx509$(SHARED_SUFFIX)	\
 		-lmbedcrypto$(SHARED_SUFFIX)
 
+ifdef USE_CRYPTO_SUBMODULE
+LOCAL_LDFLAGS += -L../crypto/library
+endif
+
 ifndef SHARED
 DEP=../library/libmbedcrypto.a ../library/libmbedx509.a ../library/libmbedtls.a
 else
diff --git a/scripts/abi_check.py b/scripts/abi_check.py
index 8f9cd0f..fe5dd3f 100755
--- a/scripts/abi_check.py
+++ b/scripts/abi_check.py
@@ -64,7 +64,7 @@
         )
         git_worktree_path = tempfile.mkdtemp()
         worktree_process = subprocess.Popen(
-            [self.git_command, "worktree", "add", git_worktree_path, git_rev],
+            [self.git_command, "worktree", "add", "--detach", git_worktree_path, git_rev],
             cwd=self.repo_path,
             stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT
@@ -75,6 +75,18 @@
             raise Exception("Checking out worktree failed, aborting")
         return git_worktree_path
 
+    def update_git_submodules(self, git_worktree_path):
+        process = subprocess.Popen(
+            [self.git_command, "submodule", "update", "--init", '--recursive'],
+            cwd=git_worktree_path,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT
+        )
+        output, _ = process.communicate()
+        self.log.info(output.decode("utf-8"))
+        if process.returncode != 0:
+            raise Exception("git submodule update failed, aborting")
+
     def build_shared_libraries(self, git_worktree_path):
         my_environment = os.environ.copy()
         my_environment["CFLAGS"] = "-g -Og"
@@ -131,6 +143,7 @@
 
     def get_abi_dump_for_ref(self, git_rev):
         git_worktree_path = self.get_clean_worktree_for_git_revision(git_rev)
+        self.update_git_submodules(git_worktree_path)
         self.build_shared_libraries(git_worktree_path)
         abi_dumps = self.get_abi_dumps_from_shared_libraries(
             git_rev, git_worktree_path
diff --git a/scripts/config.pl b/scripts/config.pl
index 3d2884c..085fc2c 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -28,6 +28,7 @@
 #   MBEDTLS_ECP_DP_M511_ENABLED
 #   MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES
 #   MBEDTLS_NO_PLATFORM_ENTROPY
+#   MBEDTLS_PSA_CRYPTO_C
 #   MBEDTLS_REMOVE_ARC4_CIPHERSUITES
 #   MBEDTLS_SSL_HW_RECORD_ACCEL
 #   MBEDTLS_RSA_NO_CRT
@@ -87,6 +88,7 @@
 MBEDTLS_ECP_DP_M511_ENABLED
 MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES
 MBEDTLS_NO_PLATFORM_ENTROPY
+MBEDTLS_PSA_CRYPTO_C
 MBEDTLS_RSA_NO_CRT
 MBEDTLS_REMOVE_ARC4_CIPHERSUITES
 MBEDTLS_SSL_HW_RECORD_ACCEL
diff --git a/tests/Makefile b/tests/Makefile
index b6e49bf..4118c14 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -12,15 +12,22 @@
 		-lmbedx509$(SHARED_SUFFIX)	\
 		-lmbedcrypto$(SHARED_SUFFIX)
 
+ifdef USE_CRYPTO_SUBMODULE
+LOCAL_LDFLAGS += -L../crypto/library
+CRYPTO := ../crypto/library/
+else
+CRYPTO := ../library/
+endif
+
 # Enable definition of various functions used throughout the testsuite
 # (gethostname, strdup, fileno...) even when compiling with -std=c99. Harmless
 # on non-POSIX platforms.
 LOCAL_CFLAGS += -D_POSIX_C_SOURCE=200809L
 
 ifndef SHARED
-DEP=../library/libmbedcrypto.a ../library/libmbedx509.a ../library/libmbedtls.a
+DEP=$(CRYPTO)libmbedcrypto.a ../library/libmbedx509.a ../library/libmbedtls.a
 else
-DEP=../library/libmbedcrypto.$(DLEXT) ../library/libmbedx509.$(DLEXT) ../library/libmbedtls.$(DLEXT)
+DEP=$(CRYPTO)libmbedcrypto.$(DLEXT) ../library/libmbedx509.$(DLEXT) ../library/libmbedtls.$(DLEXT)
 endif
 
 ifdef DEBUG
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 19baf5e..27f78ec 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -88,6 +88,11 @@
     exit 1
 fi
 
+if ! [ -f crypto/Makefile ]; then
+    echo "Please initialize the crypto submodule" >&2
+    exit 1
+fi
+
 CONFIG_H='include/mbedtls/config.h'
 CONFIG_BAK="$CONFIG_H.bak"
 
@@ -154,9 +159,12 @@
     fi
 
     command make clean
+    cd crypto
+    command make clean
+    cd ..
 
     # Remove CMake artefacts
-    find . -name .git -prune \
+    find . -name .git -prune -o \
            -iname CMakeFiles -exec rm -rf {} \+ -o \
            \( -iname cmake_install.cmake -o \
               -iname CTestTestfile.cmake -o \
@@ -165,6 +173,11 @@
     rm -f include/Makefile include/mbedtls/Makefile programs/*/Makefile
     git update-index --no-skip-worktree Makefile library/Makefile programs/Makefile tests/Makefile
     git checkout -- Makefile library/Makefile programs/Makefile tests/Makefile
+    cd crypto
+    rm -f include/Makefile include/mbedtls/Makefile programs/*/Makefile
+    git update-index --no-skip-worktree Makefile library/Makefile programs/Makefile tests/Makefile
+    git checkout -- Makefile library/Makefile programs/Makefile tests/Makefile
+    cd ..
 
     if [ -f "$CONFIG_BAK" ]; then
         mv "$CONFIG_BAK" "$CONFIG_H"
@@ -574,6 +587,66 @@
 msg "test: compat.sh ARIA + ChachaPoly"
 if_build_succeeded env OPENSSL_CMD="$OPENSSL_NEXT" tests/compat.sh -e '^$' -f 'ARIA\|CHACHA'
 
+# USE_CRYPTO_SUBMODULE: check that the build works with CMake
+msg "build: cmake, full config + USE_CRYPTO_SUBMODULE, gcc+debug"
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full # enables md4 and submodule doesn't enable md4
+scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # too slow for tests
+CC=gcc cmake -D USE_CRYPTO_SUBMODULE=1 -D CMAKE_BUILD_TYPE=Debug .
+make
+msg "test: top-level libmbedcrypto wasn't built (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded not test -f library/libmbedcrypto.a
+msg "test: libmbedcrypto symbols are from crypto files (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded objdump -g crypto/library/libmbedcrypto.a | grep -E 'crypto/library$' > /dev/null
+msg "test: libmbedcrypto uses top-level config (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded objdump -g crypto/library/libmbedcrypto.a | grep 'md4.c' > /dev/null
+msg "test: main suites (USE_CRYPTO_SUBMODULE, cmake)"
+make test
+msg "test: ssl-opt.sh (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded tests/ssl-opt.sh
+
+# USE_CRYPTO_SUBMODULE: check that the build works with make
+msg "build: make, full config + USE_CRYPTO_SUBMODULE, gcc+debug"
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full # enables md4 and submodule doesn't enable md4
+scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # too slow for tests
+make CC=gcc CFLAGS='-g' USE_CRYPTO_SUBMODULE=1
+msg "test: top-level libmbedcrypto wasn't built (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded not test -f library/libmbedcrypto.a
+msg "test: libmbedcrypto symbols are from crypto files (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded objdump -g crypto/library/libmbedcrypto.a | grep -E 'crypto/library$' > /dev/null
+msg "test: libmbedcrypto uses top-level config (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded objdump -g crypto/library/libmbedcrypto.a | grep 'md4.c' > /dev/null
+msg "test: main suites (USE_CRYPTO_SUBMODULE, make)"
+make CC=gcc USE_CRYPTO_SUBMODULE=1 test
+msg "test: ssl-opt.sh (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded tests/ssl-opt.sh
+
+# Don't USE_CRYPTO_SUBMODULE: check that the submodule is not used with make
+msg "build: make, full config - USE_CRYPTO_SUBMODULE, gcc+debug"
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full
+make CC=gcc CFLAGS='-g'
+msg "test: submodule libmbedcrypto wasn't built (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded not test -f crypto/library/libmbedcrypto.a
+msg "test: libmbedcrypto symbols are from library files (USE_CRYPTO_SUBMODULE, make)"
+if_build_succeeded objdump -g library/libmbedcrypto.a | grep -E 'library$' | not grep 'crypto' > /dev/null
+
+# Don't USE_CRYPTO_SUBMODULE: check that the submodule is not used with CMake
+msg "build: cmake, full config - USE_CRYPTO_SUBMODULE, gcc+debug"
+cleanup
+cp "$CONFIG_H" "$CONFIG_BAK"
+scripts/config.pl full
+CC=gcc cmake -D CMAKE_BUILD_TYPE=Debug .
+make
+msg "test: submodule libmbedcrypto wasn't built (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded not test -f crypto/library/libmbedcrypto.a
+msg "test: libmbedcrypto symbols are from library files (USE_CRYPTO_SUBMODULE, cmake)"
+if_build_succeeded objdump -g library/libmbedcrypto.a | grep -E 'library$' | not grep 'crypto' > /dev/null
+
 msg "build: make, full config + DEPRECATED_WARNING, gcc -O" # ~ 30s
 cleanup
 cp "$CONFIG_H" "$CONFIG_BAK"
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index 6fe6abf..4e57658 100755
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -41,8 +41,8 @@
 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';
+$ENV{'LD_LIBRARY_PATH'} = '../library:../crypto/library';
+$ENV{'DYLD_LIBRARY_PATH'} = '../library:../crypto/library';
 
 my $prefix = $^O eq "MSWin32" ? '' : './';