diff --git a/Eigen/src/Core/util/Macros.h b/Eigen/src/Core/util/Macros.h
index 00d55577d..919855597 100644
--- a/Eigen/src/Core/util/Macros.h
+++ b/Eigen/src/Core/util/Macros.h
@@ -993,8 +993,9 @@ EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void ignore_unused_variable(cons
 #endif
 
 #if !defined(EIGEN_OPTIMIZATION_BARRIER)
-#if EIGEN_COMP_GNUC
-   // According to https://gcc.gnu.org/onlinedocs/gcc/Constraints.html:
+// Implement the barrier on GNUC compilers or clang-cl.
+#if EIGEN_COMP_GNUC || (defined(__clang__) && defined(_MSC_VER))
+// According to https://gcc.gnu.org/onlinedocs/gcc/Constraints.html:
 //   X: Any operand whatsoever.
 //   r: A register operand is allowed provided that it is in a general
 //      register.
@@ -1027,37 +1028,37 @@ EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE constexpr void ignore_unused_variable(cons
 // directly for std::complex<T>, Eigen::half, Eigen::bfloat16. For these,
 // you will need to apply to the underlying POD type.
 #if EIGEN_ARCH_PPC && EIGEN_COMP_GNUC_STRICT
-   // This seems to be broken on clang. Packet4f is loaded into a single
+// This seems to be broken on clang. Packet4f is loaded into a single
 //   register rather than a vector, zeroing out some entries. Integer
 //   types also generate a compile error.
 #if EIGEN_OS_MAC
-   // General, Altivec for Apple (VSX were added in ISA v2.06):
+// General, Altivec for Apple (VSX were added in ISA v2.06):
 #define EIGEN_OPTIMIZATION_BARRIER(X) __asm__("" : "+r,v"(X));
 #else
-   // General, Altivec, VSX otherwise:
+// General, Altivec, VSX otherwise:
 #define EIGEN_OPTIMIZATION_BARRIER(X) __asm__("" : "+r,v,wa"(X));
 #endif
 #elif EIGEN_ARCH_ARM_OR_ARM64
 #ifdef __ARM_FP
-   // General, VFP or NEON.
+// General, VFP or NEON.
 // Clang doesn't like "r",
 //    error: non-trivial scalar-to-vector conversion, possible invalid
 //           constraint for vector typ
 #define EIGEN_OPTIMIZATION_BARRIER(X) __asm__("" : "+g,w"(X));
 #else
-   // Arm without VFP or NEON.
+// Arm without VFP or NEON.
 // "w" constraint will not compile.
 #define EIGEN_OPTIMIZATION_BARRIER(X) __asm__("" : "+g"(X));
 #endif
 #elif EIGEN_ARCH_i386_OR_x86_64
-   // General, SSE.
+// General, SSE.
 #define EIGEN_OPTIMIZATION_BARRIER(X) __asm__("" : "+g,x"(X));
 #else
-   // Not implemented for other architectures.
+// Not implemented for other architectures.
 #define EIGEN_OPTIMIZATION_BARRIER(X)
 #endif
 #else
-   // Not implemented for other compilers.
+// Not implemented for other compilers.
 #define EIGEN_OPTIMIZATION_BARRIER(X)
 #endif
 #endif