diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index c7f5bebdab7..6ef9f4b4c4a 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -73,6 +73,10 @@
 #include <limits.h>
 #include <errno.h>
 
+#if __cplusplus >= 202002L
+#  include <bit>
+#endif
+
 #include "libs/json11/json11.hpp"
 
 YOSYS_NAMESPACE_BEGIN
@@ -175,6 +179,41 @@ int ceil_log2(int x)
 #endif
 }
 
+// Calculate the minimum number of bits required to store an unsigned integer value.
+// Note that min_bit_width(0u) == 0.
+int min_bit_width(unsigned x)
+{
+#if __cplusplus >= 202002L
+	return std::bit_width(x);
+#else
+	int width = 0;
+	while (x) {
+		width += 1;
+		x >>= 1;
+	}
+	return width;
+#endif
+}
+
+// Calculate the minimum number of bits required to store a signed integer value,
+// using two's complement representation for negative values.
+int min_bit_width(int x)
+{
+	int sgn = 0;
+	if (x < 0) {
+		// Compute two's complement of negative value.
+		// Negative numbers are represented in two's complement form
+		// in SystemVerilog, and this is also guaranteed by C++20.
+		// C++20 also makes integral conversion of unsigned integers
+		// to signed integers well defined.
+		x = -(unsigned)x;
+		// Add a bit for sign, except for the most negative number,
+		// whose two's complement is equal to itself, i.e. MSB is set.
+		sgn += (x >= 0);
+	}
+	return sgn + min_bit_width((unsigned)x);
+}
+
 int readsome(std::istream &f, char *s, int n)
 {
 	int rc = int(f.readsome(s, n));
diff --git a/kernel/yosys.h b/kernel/yosys.h
index 0a4641d1819..43cd756b56f 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -274,6 +274,8 @@ inline void memhasher() { if (memhasher_active) memhasher_do(); }
 
 void yosys_banner();
 int ceil_log2(int x) YS_ATTRIBUTE(const);
+int min_bit_width(unsigned x);
+int min_bit_width(int x);
 
 inline std::string vstringf(const char *fmt, va_list ap)
 {