diff --git a/contrib/devtools/iwyu/bitcoin.core.imp b/contrib/devtools/iwyu/bitcoin.core.imp
index c4c4ba4cebd..789abcdadb8 100644
--- a/contrib/devtools/iwyu/bitcoin.core.imp
+++ b/contrib/devtools/iwyu/bitcoin.core.imp
@@ -1,3 +1,11 @@
-# Nothing for now.
 [
+  # Compiler intrinsics.
+  # See: https://github.com/include-what-you-use/include-what-you-use/issues/1764.
+  { "include": [ "<emmintrin.h>", "private", "<immintrin.h>", "public" ] },
+  { "include": [ "<smmintrin.h>", "private", "<immintrin.h>", "public" ] },
+  { "include": [ "<tmmintrin.h>", "private", "<immintrin.h>", "public" ] },
+
+  # libc symbols.
+  { "symbol": ["AT_HWCAP", "private", "<sys/auxv.h>", "public"] },
+  { "symbol": ["AT_HWCAP2", "private", "<sys/auxv.h>", "public"] },
 ]
diff --git a/src/crypto/chacha20.cpp b/src/crypto/chacha20.cpp
index 91064050f48..6bdffe691a6 100644
--- a/src/crypto/chacha20.cpp
+++ b/src/crypto/chacha20.cpp
@@ -8,11 +8,10 @@
 #include <crypto/common.h>
 #include <crypto/chacha20.h>
 #include <support/cleanse.h>
-#include <span.h>
 
 #include <algorithm>
 #include <bit>
-#include <cstring>
+#include <cassert>
 
 #define QUARTERROUND(a,b,c,d) \
   a += b; d = std::rotl(d ^ a, 16); \
diff --git a/src/crypto/chacha20.h b/src/crypto/chacha20.h
index 6653c2c9733..150356213d6 100644
--- a/src/crypto/chacha20.h
+++ b/src/crypto/chacha20.h
@@ -5,12 +5,11 @@
 #ifndef BITCOIN_CRYPTO_CHACHA20_H
 #define BITCOIN_CRYPTO_CHACHA20_H
 
-#include <span.h>
-
 #include <array>
 #include <cstddef>
 #include <cstdint>
-#include <cstdlib>
+#include <iterator>
+#include <span>
 #include <utility>
 
 // classes for ChaCha20 256-bit stream cipher developed by Daniel J. Bernstein
diff --git a/src/crypto/chacha20poly1305.h b/src/crypto/chacha20poly1305.h
index a6c3a668cfd..9a863dda97b 100644
--- a/src/crypto/chacha20poly1305.h
+++ b/src/crypto/chacha20poly1305.h
@@ -7,10 +7,10 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <span>
 
 #include <crypto/chacha20.h>
 #include <crypto/poly1305.h>
-#include <span.h>
 
 /** The AEAD_CHACHA20_POLY1305 authenticated encryption algorithm from RFC8439 section 2.8. */
 class AEADChaCha20Poly1305
diff --git a/src/crypto/hex_base.cpp b/src/crypto/hex_base.cpp
index e2eccf5509b..7098aba7b8a 100644
--- a/src/crypto/hex_base.cpp
+++ b/src/crypto/hex_base.cpp
@@ -5,8 +5,10 @@
 #include <crypto/hex_base.h>
 
 #include <array>
+#include <cassert>
 #include <cstring>
 #include <string>
+#include <tuple>
 
 namespace {
 
diff --git a/src/crypto/hex_base.h b/src/crypto/hex_base.h
index 704b19f8864..9975f7f6137 100644
--- a/src/crypto/hex_base.h
+++ b/src/crypto/hex_base.h
@@ -9,6 +9,7 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <span>
 #include <string>
 
 /**
diff --git a/src/crypto/hkdf_sha256_32.cpp b/src/crypto/hkdf_sha256_32.cpp
index e62249446a4..3cd2cf886ba 100644
--- a/src/crypto/hkdf_sha256_32.cpp
+++ b/src/crypto/hkdf_sha256_32.cpp
@@ -4,8 +4,9 @@
 
 #include <crypto/hkdf_sha256_32.h>
 
+#include <crypto/hmac_sha256.h>
+
 #include <cassert>
-#include <cstring>
 
 CHKDF_HMAC_SHA256_L32::CHKDF_HMAC_SHA256_L32(const unsigned char* ikm, size_t ikmlen, const std::string& salt)
 {
diff --git a/src/crypto/hkdf_sha256_32.h b/src/crypto/hkdf_sha256_32.h
index f9f343b4b76..7c5d5a7f859 100644
--- a/src/crypto/hkdf_sha256_32.h
+++ b/src/crypto/hkdf_sha256_32.h
@@ -5,10 +5,8 @@
 #ifndef BITCOIN_CRYPTO_HKDF_SHA256_32_H
 #define BITCOIN_CRYPTO_HKDF_SHA256_32_H
 
-#include <crypto/hmac_sha256.h>
-
-#include <cstdint>
-#include <cstdlib>
+#include <cstddef>
+#include <string>
 
 /** A rfc5869 HKDF implementation with HMAC_SHA256 and fixed key output length of 32 bytes (L=32) */
 class CHKDF_HMAC_SHA256_L32
diff --git a/src/crypto/hmac_sha256.cpp b/src/crypto/hmac_sha256.cpp
index 034652064e5..a95ef70849b 100644
--- a/src/crypto/hmac_sha256.cpp
+++ b/src/crypto/hmac_sha256.cpp
@@ -4,6 +4,8 @@
 
 #include <crypto/hmac_sha256.h>
 
+#include <crypto/sha256.h>
+
 #include <cstring>
 
 CHMAC_SHA256::CHMAC_SHA256(const unsigned char* key, size_t keylen)
diff --git a/src/crypto/hmac_sha256.h b/src/crypto/hmac_sha256.h
index ea8cee88085..a26947d5e0a 100644
--- a/src/crypto/hmac_sha256.h
+++ b/src/crypto/hmac_sha256.h
@@ -7,8 +7,7 @@
 
 #include <crypto/sha256.h>
 
-#include <cstdint>
-#include <cstdlib>
+#include <cstddef>
 
 /** A hasher class for HMAC-SHA-256. */
 class CHMAC_SHA256
diff --git a/src/crypto/hmac_sha512.cpp b/src/crypto/hmac_sha512.cpp
index 245ed29ec19..f37e709d13c 100644
--- a/src/crypto/hmac_sha512.cpp
+++ b/src/crypto/hmac_sha512.cpp
@@ -4,6 +4,8 @@
 
 #include <crypto/hmac_sha512.h>
 
+#include <crypto/sha512.h>
+
 #include <cstring>
 
 CHMAC_SHA512::CHMAC_SHA512(const unsigned char* key, size_t keylen)
diff --git a/src/crypto/hmac_sha512.h b/src/crypto/hmac_sha512.h
index d6bebc093c6..dfae8d05e5a 100644
--- a/src/crypto/hmac_sha512.h
+++ b/src/crypto/hmac_sha512.h
@@ -7,8 +7,7 @@
 
 #include <crypto/sha512.h>
 
-#include <cstdint>
-#include <cstdlib>
+#include <cstddef>
 
 /** A hasher class for HMAC-SHA-512. */
 class CHMAC_SHA512
diff --git a/src/crypto/muhash.cpp b/src/crypto/muhash.cpp
index 02c38c44427..c04f58ec421 100644
--- a/src/crypto/muhash.cpp
+++ b/src/crypto/muhash.cpp
@@ -7,11 +7,12 @@
 #include <crypto/chacha20.h>
 #include <crypto/common.h>
 #include <hash.h>
+#include <span.h>
+#include <uint256.h>
 #include <util/check.h>
 
 #include <bit>
-#include <cassert>
-#include <cstdio>
+#include <cstring>
 #include <limits>
 
 namespace {
diff --git a/src/crypto/muhash.h b/src/crypto/muhash.h
index f3409373236..5e2be323383 100644
--- a/src/crypto/muhash.h
+++ b/src/crypto/muhash.h
@@ -6,9 +6,12 @@
 #define BITCOIN_CRYPTO_MUHASH_H
 
 #include <serialize.h>
-#include <uint256.h>
 
+#include <cstddef>
 #include <cstdint>
+#include <span>
+
+class uint256;
 
 class Num3072
 {
diff --git a/src/crypto/poly1305.cpp b/src/crypto/poly1305.cpp
index c9c066b3097..d6762a1f1d9 100644
--- a/src/crypto/poly1305.cpp
+++ b/src/crypto/poly1305.cpp
@@ -5,8 +5,6 @@
 #include <crypto/common.h>
 #include <crypto/poly1305.h>
 
-#include <cstring>
-
 namespace poly1305_donna {
 
 // Based on the public domain implementation by Andrew Moon
diff --git a/src/crypto/poly1305.h b/src/crypto/poly1305.h
index 494f7cdd4d8..af4aede2583 100644
--- a/src/crypto/poly1305.h
+++ b/src/crypto/poly1305.h
@@ -8,8 +8,9 @@
 #include <span.h>
 
 #include <cassert>
+#include <cstddef>
 #include <cstdint>
-#include <cstdlib>
+#include <span>
 
 #define POLY1305_BLOCK_SIZE 16
 
diff --git a/src/crypto/sha256.cpp b/src/crypto/sha256.cpp
index d75d01b6b7c..8ad9a85d56c 100644
--- a/src/crypto/sha256.cpp
+++ b/src/crypto/sha256.cpp
@@ -10,7 +10,7 @@
 #include <cstring>
 
 #if !defined(DISABLE_OPTIMIZED_SHA256)
-#include <compat/cpuid.h>
+#include <compat/cpuid.h> // IWYU pragma: keep
 
 #if defined(__linux__) && defined(ENABLE_ARM_SHANI)
 #include <sys/auxv.h>
diff --git a/src/crypto/sha256_arm_shani.cpp b/src/crypto/sha256_arm_shani.cpp
index 2ea1d9c2acc..a778e871a12 100644
--- a/src/crypto/sha256_arm_shani.cpp
+++ b/src/crypto/sha256_arm_shani.cpp
@@ -13,7 +13,6 @@
 #include <array>
 #include <cstdint>
 #include <cstddef>
-#include <arm_acle.h>
 #include <arm_neon.h>
 
 namespace {
diff --git a/src/crypto/sha256_sse4.cpp b/src/crypto/sha256_sse4.cpp
index d0a34934d80..3de30f7408a 100644
--- a/src/crypto/sha256_sse4.cpp
+++ b/src/crypto/sha256_sse4.cpp
@@ -5,11 +5,11 @@
 // This is a translation to GCC extended asm syntax from YASM code by Intel
 // (available at the bottom of this file).
 
+#if defined(__x86_64__) || defined(__amd64__)
+
 #include <cstdint>
 #include <cstdlib>
 
-#if defined(__x86_64__) || defined(__amd64__)
-
 namespace sha256_sse4
 {
 void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
diff --git a/src/crypto/sha256_x86_shani.cpp b/src/crypto/sha256_x86_shani.cpp
index 5ee957aaa78..daccdc51638 100644
--- a/src/crypto/sha256_x86_shani.cpp
+++ b/src/crypto/sha256_x86_shani.cpp
@@ -8,6 +8,7 @@
 
 #if defined(ENABLE_SSE41) && defined(ENABLE_X86_SHANI)
 
+#include <cstddef>
 #include <cstdint>
 #include <immintrin.h>
 
diff --git a/src/crypto/sha3.cpp b/src/crypto/sha3.cpp
index 4c61bce5f62..f6844476abe 100644
--- a/src/crypto/sha3.cpp
+++ b/src/crypto/sha3.cpp
@@ -9,9 +9,9 @@
 #include <crypto/common.h>
 
 #include <algorithm>
-#include <array>
 #include <bit>
-#include <cstdint>
+#include <cassert>
+#include <iterator>
 #include <span>
 
 void KeccakF(uint64_t (&st)[25])
diff --git a/src/crypto/sha3.h b/src/crypto/sha3.h
index 7a538e4a275..91cdb5ca7ab 100644
--- a/src/crypto/sha3.h
+++ b/src/crypto/sha3.h
@@ -5,10 +5,9 @@
 #ifndef BITCOIN_CRYPTO_SHA3_H
 #define BITCOIN_CRYPTO_SHA3_H
 
-#include <span.h>
-
 #include <cstdint>
 #include <cstdlib>
+#include <span>
 
 //! The Keccak-f[1600] transform.
 void KeccakF(uint64_t (&st)[25]);
diff --git a/src/crypto/siphash.cpp b/src/crypto/siphash.cpp
index dda28a6ced4..1a9eb771a82 100644
--- a/src/crypto/siphash.cpp
+++ b/src/crypto/siphash.cpp
@@ -4,7 +4,11 @@
 
 #include <crypto/siphash.h>
 
+#include <uint256.h>
+
 #include <bit>
+#include <cassert>
+#include <span>
 
 #define SIPROUND do { \
     v0 += v1; v1 = std::rotl(v1, 13); v1 ^= v0; \
diff --git a/src/crypto/siphash.h b/src/crypto/siphash.h
index 4c6a39e0b68..8d41a083ac8 100644
--- a/src/crypto/siphash.h
+++ b/src/crypto/siphash.h
@@ -6,9 +6,9 @@
 #define BITCOIN_CRYPTO_SIPHASH_H
 
 #include <cstdint>
+#include <span>
 
-#include <span.h>
-#include <uint256.h>
+class uint256;
 
 /** SipHash-2-4 */
 class CSipHasher