diff --git a/GNUmakefile b/GNUmakefile
index cf068d27..5541cc10 100755
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -1057,8 +1057,13 @@ endif
 # Cryptogams AES for ARMv4 and above. We couple to ARMv7.
 # Avoid iOS. It cannot consume the assembly.
 ifeq ($(IS_ARM32),1)
-  CRYPTOGAMS_ARCH_FLAG = -march=armv7-a
-  CRYPTOGAMS_ARCH_FLAG += -Wa,--noexecstack
+  ifeq ($(CLANG_COMPILER),1)
+    CRYPTOGAMS_ARMV7_FLAG = -march=armv7-a -Wa,--noexecstack
+    CRYPTOGAMS_ARMV7_THUMB_FLAG = -march=armv7-a -mthumb -Wa,--noexecstack
+  else
+    CRYPTOGAMS_ARMV7_FLAG = -march=armv7-a -Wa,--noexecstack
+    CRYPTOGAMS_ARMV7_THUMB_FLAG = -march=armv7-a -Wa,--noexecstack
+  endif
   SRCS += aes_armv4.S sha1_armv4.S sha256_armv4.S sha512_armv4.S
 endif
 
@@ -1421,9 +1426,9 @@ ifeq ($(wildcard GNUmakefile.deps),GNUmakefile.deps)
 -include GNUmakefile.deps
 endif # Dependencies
 
-# Cryptogams ARM asm implementation.
+# Cryptogams ARM asm implementation. AES needs -mthumb for Clang
 aes_armv4.o : aes_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_THUMB_FLAG) -c) $<
 
 # SSSE3 or NEON available
 aria_simd.o : aria_simd.cpp
@@ -1507,15 +1512,15 @@ sha_simd.o : sha_simd.cpp
 
 # Cryptogams ARM asm implementation.
 sha1_armv4.o : sha1_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 # Cryptogams ARM asm implementation.
 sha256_armv4.o : sha256_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 # Cryptogams ARM asm implementation.
 sha512_armv4.o : sha512_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 sha3_simd.o : sha3_simd.cpp
 	$(CXX) $(strip $(CXXFLAGS) $(SHA3_FLAG) -c) $<
diff --git a/GNUmakefile-cross b/GNUmakefile-cross
index dd6237e3..ccf8edd3 100755
--- a/GNUmakefile-cross
+++ b/GNUmakefile-cross
@@ -589,13 +589,15 @@ SRCS := cryptlib.cpp cpu.cpp integer.cpp $(filter-out cryptlib.cpp cpu.cpp integ
 INCL := $(filter-out resource.h,$(sort $(wildcard *.h)))
 
 # Cryptogams AES for ARMv4 and above. We couple to ARMv7.
-# Avoid iOS. It cannot consume the assembly.
 ifeq ($(IS_ARM32),1)
-  ifneq ($(IS_IOS),1)
-    CRYPTOGAMS_ARCH_FLAG = -march=armv7-a
-    CRYPTOGAMS_ARCH_FLAG += -Wa,--noexecstack
-    SRCS += aes_armv4.S sha1_armv4.S sha256_armv4.S sha512_armv4.S
+  ifeq ($(CLANG_COMPILER),1)
+    CRYPTOGAMS_ARMV7_FLAG = -march=armv7-a -Wa,--noexecstack
+    CRYPTOGAMS_ARMV7_THUMB_FLAG = -march=armv7-a -mthumb -Wa,--noexecstack
+  else
+    CRYPTOGAMS_ARMV7_FLAG = -march=armv7-a -Wa,--noexecstack
+    CRYPTOGAMS_ARMV7_THUMB_FLAG = -march=armv7-a -Wa,--noexecstack
   endif
+  SRCS += aes_armv4.S sha1_armv4.S sha256_armv4.S sha512_armv4.S
 endif
 
 # List cryptlib.cpp first, then cpu.cpp, then integer.cpp to tame C++ static initialization problems.
@@ -798,9 +800,9 @@ ifeq ($(wildcard GNUmakefile.deps),GNUmakefile.deps)
 -include GNUmakefile.deps
 endif # Dependencies
 
-# Cryptogams ARM asm implementation.
+# Cryptogams ARM asm implementation. AES needs -mthumb for Clang
 aes_armv4.o : aes_armv4.S
-	$(CXX) $(strip $(CXXFLAGS) -fpermissive $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_THUMB_FLAG) -c) $<
 
 cpu-features.o: cpu-features.h cpu-features.c
 	$(CXX) $(strip $(CXXFLAGS) -fpermissive -c) cpu-features.c
@@ -867,15 +869,15 @@ sha_simd.o : sha_simd.cpp
 
 # Cryptogams ARM asm implementation.
 sha1_armv4.o : sha1_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 # Cryptogams ARM asm implementation.
 sha256_armv4.o : sha256_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 # Cryptogams ARM asm implementation.
 sha512_armv4.o : sha512_armv4.S
-	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARCH_FLAG) -c) $<
+	$(CC) $(strip $(CXXFLAGS) $(CRYPTOGAMS_ARMV7_FLAG) -c) $<
 
 # SSE4.2/SHA-NI or ARMv8a available
 shacal2_simd.o : shacal2_simd.cpp
diff --git a/config_asm.h b/config_asm.h
index 6a001078..cba714a3 100644
--- a/config_asm.h
+++ b/config_asm.h
@@ -359,13 +359,10 @@
 // about 50% faster than C/C++, and SHA implementation is about 30% faster
 // than C/C++. Define this to use the Cryptogams AES and SHA implementations
 // on GNU Linux systems. When defined, Crypto++ will use aes_armv4.S,
-// sha1_armv4.S and sha256_armv4.S. LLVM miscompiles aes_armv4.S so disable
-// under Clang. Also see https://bugs.llvm.org/show_bug.cgi?id=38133.
+// sha1_armv4.S and sha256_armv4.S.
 #if !defined(CRYPTOPP_DISABLE_ASM) && defined(__arm__)
-# if defined(__GNUC__) && !defined(__clang__)
-#  define CRYPTOGAMS_ARM_AES      1
-# endif
 # if defined(__GNUC__) || defined(__clang__)
+#  define CRYPTOGAMS_ARM_AES      1
 #  define CRYPTOGAMS_ARM_SHA1     1
 #  define CRYPTOGAMS_ARM_SHA256   1
 #  define CRYPTOGAMS_ARM_SHA512   1