diff --git a/conf/config.neon b/conf/config.neon
index 4418c200c3..88a6568232 100644
--- a/conf/config.neon
+++ b/conf/config.neon
@@ -1268,6 +1268,11 @@ services:
 		tags:
 			- phpstan.dynamicStaticMethodThrowTypeExtension
 
+	-
+		class: PHPStan\Type\Php\StrContainingTypeSpecifyingExtension
+		tags:
+			- phpstan.typeSpecifier.functionTypeSpecifyingExtension
+
 	-
 		class: PHPStan\Type\Php\SimpleXMLElementClassPropertyReflectionExtension
 		tags:
diff --git a/src/Type/Php/StrContainingTypeSpecifyingExtension.php b/src/Type/Php/StrContainingTypeSpecifyingExtension.php
new file mode 100644
index 0000000000..dddbfe73e5
--- /dev/null
+++ b/src/Type/Php/StrContainingTypeSpecifyingExtension.php
@@ -0,0 +1,101 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Arg;
+use PhpParser\Node\Expr\BinaryOp\BooleanAnd;
+use PhpParser\Node\Expr\BinaryOp\NotIdentical;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Name;
+use PhpParser\Node\Scalar\String_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Analyser\SpecifiedTypes;
+use PHPStan\Analyser\TypeSpecifier;
+use PHPStan\Analyser\TypeSpecifierAwareExtension;
+use PHPStan\Analyser\TypeSpecifierContext;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
+use PHPStan\Type\Accessory\AccessoryNumericStringType;
+use PHPStan\Type\FunctionTypeSpecifyingExtension;
+use PHPStan\Type\IntersectionType;
+use PHPStan\Type\StringType;
+use function array_key_exists;
+use function count;
+use function strtolower;
+
+final class StrContainingTypeSpecifyingExtension implements FunctionTypeSpecifyingExtension, TypeSpecifierAwareExtension
+{
+
+	/** @var array<string, array{0: int, 1: int}> */
+	private array $strContainingFunctions = [
+		'fnmatch' => [1, 0],
+		'str_contains' => [0, 1],
+		'str_starts_with' => [0, 1],
+		'str_ends_with' => [0, 1],
+		'strpos' => [0, 1],
+		'strrpos' => [0, 1],
+		'stripos' => [0, 1],
+		'strripos' => [0, 1],
+		'strstr' => [0, 1],
+	];
+
+	private TypeSpecifier $typeSpecifier;
+
+	public function setTypeSpecifier(TypeSpecifier $typeSpecifier): void
+	{
+		$this->typeSpecifier = $typeSpecifier;
+	}
+
+	public function isFunctionSupported(FunctionReflection $functionReflection, FuncCall $node, TypeSpecifierContext $context): bool
+	{
+		return array_key_exists(strtolower($functionReflection->getName()), $this->strContainingFunctions)
+			&& $context->truthy();
+	}
+
+	public function specifyTypes(FunctionReflection $functionReflection, FuncCall $node, Scope $scope, TypeSpecifierContext $context): SpecifiedTypes
+	{
+		$args = $node->getArgs();
+
+		if (count($args) >= 2) {
+			[$hackstackArg, $needleArg] = $this->strContainingFunctions[strtolower($functionReflection->getName())];
+
+			$haystackType = $scope->getType($args[$hackstackArg]->value);
+			$needleType = $scope->getType($args[$needleArg]->value);
+
+			if ($needleType->isNonEmptyString()->yes() && $haystackType->isString()->yes()) {
+				$accessories = [
+					new StringType(),
+					new AccessoryNonEmptyStringType(),
+				];
+
+				if ($haystackType->isLiteralString()->yes()) {
+					$accessories[] = new AccessoryLiteralStringType();
+				}
+				if ($haystackType->isNumericString()->yes()) {
+					$accessories[] = new AccessoryNumericStringType();
+				}
+
+				return $this->typeSpecifier->create(
+					$args[$hackstackArg]->value,
+					new IntersectionType($accessories),
+					$context,
+					false,
+					$scope,
+					new BooleanAnd(
+						new NotIdentical(
+							$args[$needleArg]->value,
+							new String_(''),
+						),
+						new FuncCall(new Name('FAUX_FUNCTION'), [
+							new Arg($args[$needleArg]->value),
+						]),
+					),
+				);
+			}
+		}
+
+		return new SpecifiedTypes();
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index eff22135bc..92b3dd7059 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -902,6 +902,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7068.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7115.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/constant-array-type-identical.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/non-empty-string-str-containing-fns.php');
 	}
 
 	/**
diff --git a/tests/PHPStan/Analyser/data/non-empty-string-str-containing-fns.php b/tests/PHPStan/Analyser/data/non-empty-string-str-containing-fns.php
new file mode 100644
index 0000000000..ba98370913
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/non-empty-string-str-containing-fns.php
@@ -0,0 +1,123 @@
+<?php
+
+namespace NonEmptyStringStrContains;
+
+use function PHPStan\Testing\assertType;
+
+class Foo {
+	/**
+	 * @param non-empty-string $nonES
+	 * @param numeric-string $numS
+	 * @param literal-string $literalS
+	 * @param non-empty-string&numeric-string $nonEAndNumericS
+	 */
+	public function strContains(string $s, string $s2, $nonES, $numS, $literalS, $nonEAndNumericS, int $i): void
+	{
+		if (str_contains($s, ':')) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (str_contains($s, $s2)) {
+			assertType('string', $s);
+		}
+
+		if (str_contains($s, $nonES)) {
+			assertType('non-empty-string', $s);
+		}
+		if (str_contains($s, $numS)) {
+			assertType('non-empty-string', $s);
+		}
+		if (str_contains($s, $literalS)) {
+			assertType('string', $s);
+		}
+
+		if (str_contains($s, $nonEAndNumericS)) {
+			assertType('non-empty-string', $s);
+		}
+		if (str_contains($numS, $nonEAndNumericS)) {
+			assertType('non-empty-string&numeric-string', $numS);
+		}
+
+		if (str_contains($nonES, $s)) {
+			assertType('non-empty-string', $nonES);
+		}
+		if (str_contains($nonEAndNumericS, $s)) {
+			assertType('non-empty-string&numeric-string', $nonEAndNumericS);
+		}
+
+		if (str_contains($i, $s2)) {
+			assertType('int', $i);
+		}
+	}
+
+	public function variants(string $s) {
+		if (fnmatch("*gr[ae]y", $s)) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (str_starts_with($s, ':')) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (str_ends_with($s, ':')) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (strpos($s, ':') !== false) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+		if (strpos($s, ':') === false) {
+			assertType('string', $s);
+		}
+		assertType('string', $s);
+
+		if (strpos($s, ':') === 5) {
+			assertType('string', $s); // could be non-empty-string
+		}
+		assertType('string', $s);
+		if (strpos($s, ':') !== 5) {
+			assertType('string', $s);
+		}
+		assertType('string', $s);
+
+		if (strrpos($s, ':') !== false) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (stripos($s, ':') !== false) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (strripos($s, ':') !== false) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+
+		if (strstr($s, ':') === 'hallo') {
+			assertType('string', $s); // could be non-empty-string
+		}
+		assertType('string', $s);
+		if (strstr($s, ':', true) === 'hallo') {
+			assertType('string', $s); // could be non-empty-string
+		}
+		assertType('string', $s);
+		if (strstr($s, ':', true) !== false) {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+		if (strstr($s, ':', true) === false) {
+			assertType('string', $s);
+		} else {
+			assertType('non-empty-string', $s);
+		}
+		assertType('string', $s);
+	}
+
+}
diff --git a/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php b/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
index ea96a4e825..1d624ad3a9 100644
--- a/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php
@@ -528,4 +528,11 @@ public function testSlevomatCsInArrayBug(): void
 		$this->analyse([__DIR__ . '/data/slevomat-cs-in-array.php'], []);
 	}
 
+	public function testNonEmptySpecifiedString(): void
+	{
+		$this->checkAlwaysTrueCheckTypeFunctionCall = true;
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/non-empty-string-impossible-type.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/data/non-empty-string-impossible-type.php b/tests/PHPStan/Rules/Comparison/data/non-empty-string-impossible-type.php
new file mode 100644
index 0000000000..d2092228d2
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/non-empty-string-impossible-type.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace NonEmptyStringImpossibleType;
+
+class Foo {
+	private function isPrefixedInterface(string $shortClassName): bool
+	{
+		if (strlen($shortClassName) <= 3) {
+			return false;
+		}
+
+		if (! \str_starts_with($shortClassName, 'I')) {
+			return false;
+		}
+
+		if (! ctype_upper($shortClassName[1])) {
+			return false;
+		}
+
+		return ctype_lower($shortClassName[2]);
+	}
+}