diff --git a/CMakeLists.txt b/CMakeLists.txt
index fab1b3bf..c614a65a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -274,7 +274,7 @@ if(MSAN)
 
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer")
-  set(OPENSSL_NO_ASM "1")
+  set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer")
 endif()
 
 if(ASAN)
@@ -284,7 +284,6 @@ if(ASAN)
 
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fsanitize-address-use-after-scope -fno-omit-frame-pointer")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fsanitize-address-use-after-scope -fno-omit-frame-pointer")
-  set(OPENSSL_NO_ASM "1")
 endif()
 
 if(CFI)
diff --git a/crypto/crypto.c b/crypto/crypto.c
index 93e2f824..783d7d96 100644
--- a/crypto/crypto.c
+++ b/crypto/crypto.c
@@ -19,19 +19,6 @@
 #include "internal.h"
 
 
-#if defined(OPENSSL_MSAN) && !defined(OPENSSL_NO_ASM)
-// MSan works by instrumenting memory accesses in the compiler. Accesses from
-// uninstrumented code, such as assembly, are invisible to it. MSan will
-// incorrectly report reads from assembly-initialized memory as uninitialized.
-// If building BoringSSL with MSan, exclude assembly files from the build and
-// define OPENSSL_NO_ASM.
-//
-// This is checked here rather than in a header because the consumer might not
-// define OPENSSL_NO_ASM. It is only necessary for BoringSSL source files to be
-// built with it.
-#error "BoringSSL must be built with assembly disabled to use MSan."
-#endif
-
 #if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_STATIC_ARMCAP) && \
     (defined(OPENSSL_X86) || defined(OPENSSL_X86_64) || \
      defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64) || \
diff --git a/crypto/curve25519/asm/x25519-asm-arm.S b/crypto/curve25519/asm/x25519-asm-arm.S
index 5a1cca4a..905af077 100644
--- a/crypto/curve25519/asm/x25519-asm-arm.S
+++ b/crypto/curve25519/asm/x25519-asm-arm.S
@@ -17,6 +17,12 @@
  * domain licensed but the standard ISC license is included above to keep
  * licensing simple. */
 
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)
+#define OPENSSL_NO_ASM
+#endif
+#endif
+
 #if !defined(OPENSSL_NO_ASM) && defined(__arm__) && !defined(__APPLE__)
 
 #if defined(BORINGSSL_PREFIX)
diff --git a/crypto/perlasm/arm-xlate.pl b/crypto/perlasm/arm-xlate.pl
index a0adeb5f..fffba808 100755
--- a/crypto/perlasm/arm-xlate.pl
+++ b/crypto/perlasm/arm-xlate.pl
@@ -130,6 +130,16 @@ sub expand_line {
     return $line;
 }
 
+print <<___;
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)
+#define OPENSSL_NO_ASM
+#endif
+#endif
+
+#if !defined(OPENSSL_NO_ASM)
+___
+
 print "#if defined(__arm__)\n" if ($flavour eq "linux32");
 print "#if defined(__aarch64__)\n" if ($flavour eq "linux64");
 
@@ -184,5 +194,6 @@ while(my $line=<>) {
 }
 
 print "#endif\n" if ($flavour eq "linux32" || $flavour eq "linux64");
+print "#endif  // !OPENSSL_NO_ASM";
 
 close STDOUT;
diff --git a/crypto/perlasm/ppc-xlate.pl b/crypto/perlasm/ppc-xlate.pl
index de796d73..8013058d 100644
--- a/crypto/perlasm/ppc-xlate.pl
+++ b/crypto/perlasm/ppc-xlate.pl
@@ -255,6 +255,16 @@ my $darn = sub {
     "	.long	".sprintf "0x%X",(31<<26)|($rt<<21)|($l<<16)|(755<<1);
 };
 
+print <<___;
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)"
+#define OPENSSL_NO_ASM"
+#endif
+#endif
+
+#if !defined(OPENSSL_NO_ASM) && defined(__powerpc64__)
+___
+
 while($line=<>) {
 
     $line =~ s|[#!;].*$||;	# get rid of asm-style comments...
@@ -296,4 +306,6 @@ while($line=<>) {
     print "\n";
 }
 
+print "#endif  // !OPENSSL_NO_ASM && __powerpc64__";
+
 close STDOUT;
diff --git a/crypto/perlasm/x86_64-xlate.pl b/crypto/perlasm/x86_64-xlate.pl
index f6a57e02..3ec9b6c6 100755
--- a/crypto/perlasm/x86_64-xlate.pl
+++ b/crypto/perlasm/x86_64-xlate.pl
@@ -1139,10 +1139,21 @@ ___
 OPTION	DOTNAME
 ___
 }
-print STDOUT "#if defined(__x86_64__) && !defined(OPENSSL_NO_ASM)\n" if ($gas);
-print STDOUT "#if defined(BORINGSSL_PREFIX)\n" if ($gas);
-print STDOUT "#include <boringssl_prefix_symbols_asm.h>\n" if ($gas);
-print STDOUT "#endif\n" if ($gas);
+
+if ($gas) {
+	print <<___;
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)
+#define OPENSSL_NO_ASM
+#endif
+#endif
+
+#if defined(__x86_64__) && !defined(OPENSSL_NO_ASM)
+#if defined(BORINGSSL_PREFIX)
+#include <boringssl_prefix_symbols_asm.h>
+#endif
+___
+}
 
 while(defined(my $line=<>)) {
 
diff --git a/crypto/poly1305/poly1305_arm_asm.S b/crypto/poly1305/poly1305_arm_asm.S
index 06e7bd99..04f7c4cd 100644
--- a/crypto/poly1305/poly1305_arm_asm.S
+++ b/crypto/poly1305/poly1305_arm_asm.S
@@ -1,3 +1,9 @@
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)
+#define OPENSSL_NO_ASM
+#endif
+#endif
+
 #if defined(__arm__) && !defined(OPENSSL_NO_ASM) && !defined(__APPLE__)
 
 #if defined(BORINGSSL_PREFIX)
diff --git a/include/openssl/base.h b/include/openssl/base.h
index f86968bf..b68423ec 100644
--- a/include/openssl/base.h
+++ b/include/openssl/base.h
@@ -231,9 +231,17 @@ extern "C" {
 #endif
 #if __has_feature(memory_sanitizer)
 #define OPENSSL_MSAN
+#define OPENSSL_ASM_INCOMPATIBLE
 #endif
 #endif
 
+#if defined(OPENSSL_ASM_INCOMPATIBLE)
+#undef OPENSSL_ASM_INCOMPATIBLE
+#if !defined(OPENSSL_NO_ASM)
+#define OPENSSL_NO_ASM
+#endif
+#endif  // OPENSSL_ASM_INCOMPATIBLE
+
 // CRYPTO_THREADID is a dummy value.
 typedef int CRYPTO_THREADID;