diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -855,7 +855,8 @@
     if (!isShiftedImm() && (!isImm() || !isa<MCConstantExpr>(getImm())))
       return DiagnosticPredicateTy::NoMatch;
 
-    bool IsByte = std::is_same<int8_t, std::make_signed_t<T>>::value;
+    bool IsByte = std::is_same<int8_t, std::make_signed_t<T>>::value ||
+                  std::is_same<signed char, std::make_signed_t<T>>::value;
     if (auto ShiftedImm = getShiftedVal<8>())
       if (!(IsByte && ShiftedImm->second) &&
           AArch64_AM::isSVECpyImm<T>(uint64_t(ShiftedImm->first)
@@ -872,7 +873,8 @@
     if (!isShiftedImm() && (!isImm() || !isa<MCConstantExpr>(getImm())))
       return DiagnosticPredicateTy::NoMatch;
 
-    bool IsByte = std::is_same<int8_t, std::make_signed_t<T>>::value;
+    bool IsByte = std::is_same<int8_t, std::make_signed_t<T>>::value ||
+                  std::is_same<signed char, std::make_signed_t<T>>::value;
     if (auto ShiftedImm = getShiftedVal<8>())
       if (!(IsByte && ShiftedImm->second) &&
           AArch64_AM::isSVEAddSubImm<T>(ShiftedImm->first
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AddressingModes.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AddressingModes.h
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AddressingModes.h
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AddressingModes.h
@@ -763,7 +763,8 @@
   bool IsImm8 = int8_t(Imm) == Imm;
   bool IsImm16 = int16_t(Imm & ~0xff) == Imm;
 
-  if (std::is_same<int8_t, std::make_signed_t<T>>::value)
+  if (std::is_same<int8_t, std::make_signed_t<T>>::value ||
+      std::is_same<signed char, std::make_signed_t<T>>::value)
     return IsImm8 || uint8_t(Imm) == Imm;
 
   if (std::is_same<int16_t, std::make_signed_t<T>>::value)
@@ -775,7 +776,8 @@
 /// Returns true if Imm is valid for ADD/SUB.
 template <typename T>
 static inline bool isSVEAddSubImm(int64_t Imm) {
-  bool IsInt8t = std::is_same<int8_t, std::make_signed_t<T>>::value;
+  bool IsInt8t = std::is_same<int8_t, std::make_signed_t<T>>::value ||
+                 std::is_same<signed char, std::make_signed_t<T>>::value;
   return uint8_t(Imm) == Imm || (!IsInt8t && uint16_t(Imm & ~0xff) == Imm);
 }