diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index a48796612..f29f5f137 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -697,15 +697,15 @@ vector<string> CompilerStack::contractNames() const
 	return contractNames;
 }
 
-string const CompilerStack::lastContractName() const
+string const CompilerStack::lastContractName(optional<string> const& _sourceName) const
 {
 	if (m_stackState < AnalysisPerformed)
 		BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Parsing was not successful."));
 	// try to find some user-supplied contract
 	string contractName;
 	for (auto const& it: m_sources)
-		for (ASTPointer<ASTNode> const& node: it.second.ast->nodes())
-			if (auto contract = dynamic_cast<ContractDefinition const*>(node.get()))
+		if (_sourceName.value_or(it.first) == it.first)
+			for (auto const* contract: ASTNode::filteredNodes<ContractDefinition>(it.second.ast->nodes()))
 				contractName = contract->fullyQualifiedName();
 	return contractName;
 }
diff --git a/libsolidity/interface/CompilerStack.h b/libsolidity/interface/CompilerStack.h
index ed3245505..1a02fb226 100644
--- a/libsolidity/interface/CompilerStack.h
+++ b/libsolidity/interface/CompilerStack.h
@@ -261,8 +261,8 @@ public:
 	/// @returns a list of the contract names in the sources.
 	std::vector<std::string> contractNames() const;
 
-	/// @returns the name of the last contract.
-	std::string const lastContractName() const;
+	/// @returns the name of the last contract. If _sourceName is defined the last contract of that source will be returned.
+	std::string const lastContractName(std::optional<std::string> const& _sourceName = std::nullopt) const;
 
 	/// @returns either the contract's name or a mixture of its name and source file, sanitized for filesystem use
 	std::string const filesystemFriendlyName(std::string const& _contractName) const;
diff --git a/test/Common.cpp b/test/Common.cpp
index 8406727d3..a020312a8 100644
--- a/test/Common.cpp
+++ b/test/Common.cpp
@@ -21,6 +21,7 @@
 #include <test/Common.h>
 
 #include <libsolutil/Assertions.h>
+#include <boost/algorithm/string.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/program_options.hpp>
 
@@ -222,4 +223,19 @@ void CommonOptions::setSingleton(std::unique_ptr<CommonOptions const>&& _instanc
 
 std::unique_ptr<CommonOptions const> CommonOptions::m_singleton = nullptr;
 
+bool isValidSemanticTestPath(boost::filesystem::path const& _testPath)
+{
+	bool insideSemanticTests = false;
+	fs::path testPathPrefix;
+	for (auto const& element: _testPath)
+	{
+		testPathPrefix /= element;
+		if (boost::ends_with(canonical(testPathPrefix).generic_string(), "/test/libsolidity/semanticTests"))
+			insideSemanticTests = true;
+		if (insideSemanticTests && boost::starts_with(element.string(), "_"))
+			return false;
+	}
+	return true;
+}
+
 }
diff --git a/test/Common.h b/test/Common.h
index 2434e49ce..0cc78c121 100644
--- a/test/Common.h
+++ b/test/Common.h
@@ -86,4 +86,9 @@ private:
 	static std::unique_ptr<CommonOptions const> m_singleton;
 };
 
+/// @return true if it is ok to treat the file located under the specified path as a semantic test.
+/// I.e. if the test is located in the semantic test directory and is not excluded due to being a part of external sources.
+/// Note: @p _testPath can be relative but must include at least the `/test/libsolidity/semanticTests/` part
+bool isValidSemanticTestPath(boost::filesystem::path const& _testPath);
+
 }
diff --git a/test/CommonSyntaxTest.cpp b/test/CommonSyntaxTest.cpp
index 1756e25af..11f654281 100644
--- a/test/CommonSyntaxTest.cpp
+++ b/test/CommonSyntaxTest.cpp
@@ -59,7 +59,7 @@ int parseUnsignedInteger(string::iterator& _it, string::iterator _end)
 
 CommonSyntaxTest::CommonSyntaxTest(string const& _filename, langutil::EVMVersion _evmVersion):
 	EVMVersionRestrictedTestCase(_filename),
-	m_sources(m_reader.sources().sources),
+	m_sources(m_reader.sources()),
 	m_expectations(parseExpectations(m_reader.stream())),
 	m_evmVersion(_evmVersion)
 {
@@ -92,12 +92,13 @@ void CommonSyntaxTest::printExpectationAndError(ostream& _stream, string const&
 
 void CommonSyntaxTest::printSource(ostream& _stream, string const& _linePrefix, bool _formatted) const
 {
-	if (m_sources.empty())
+	if (m_sources.sources.empty())
 		return;
 
-	bool outputSourceNames = (m_sources.size() != 1 || !m_sources.begin()->first.empty());
+	assert(m_sources.externalSources.empty());
+	bool outputSourceNames = (m_sources.sources.size() != 1 || !m_sources.sources.begin()->first.empty());
 
-	for (auto const& [name, source]: m_sources)
+	for (auto const& [name, source]: m_sources.sources)
 		if (_formatted)
 		{
 			if (source.empty())
diff --git a/test/CommonSyntaxTest.h b/test/CommonSyntaxTest.h
index db3a6e50c..169824252 100644
--- a/test/CommonSyntaxTest.h
+++ b/test/CommonSyntaxTest.h
@@ -20,6 +20,7 @@
 
 #include <test/libsolidity/AnalysisFramework.h>
 #include <test/TestCase.h>
+#include <test/TestCaseReader.h>
 #include <liblangutil/Exceptions.h>
 #include <libsolutil/AnsiColorized.h>
 
@@ -81,7 +82,7 @@ protected:
 
 	static std::vector<SyntaxTestError> parseExpectations(std::istream& _stream);
 
-	std::map<std::string, std::string> m_sources;
+	frontend::test::SourceMap m_sources;
 	std::vector<SyntaxTestError> m_expectations;
 	std::vector<SyntaxTestError> m_errorList;
 	langutil::EVMVersion const m_evmVersion;
diff --git a/test/ExecutionFramework.h b/test/ExecutionFramework.h
index 1b320776e..c1d82856a 100644
--- a/test/ExecutionFramework.h
+++ b/test/ExecutionFramework.h
@@ -60,7 +60,8 @@ public:
 		u256 const& _value = 0,
 		std::string const& _contractName = "",
 		bytes const& _arguments = {},
-		std::map<std::string, util::h160> const& _libraryAddresses = {}
+		std::map<std::string, util::h160> const& _libraryAddresses = {},
+		std::optional<std::string> const& _sourceName = std::nullopt
 	) = 0;
 
 	bytes const& compileAndRun(
diff --git a/test/TestCaseReader.cpp b/test/TestCaseReader.cpp
index 12dbedf6d..26b625734 100644
--- a/test/TestCaseReader.cpp
+++ b/test/TestCaseReader.cpp
@@ -18,24 +18,29 @@
 
 #include <test/TestCaseReader.h>
 
+#include <libsolidity/parsing/Parser.h>
 #include <libsolutil/StringUtils.h>
+#include <libsolutil/CommonIO.h>
 
 #include <boost/algorithm/string.hpp>
 #include <boost/throw_exception.hpp>
+#include <boost/filesystem.hpp>
 
 #include <range/v3/view/map.hpp>
 
 using namespace std;
+using namespace solidity::langutil;
 using namespace solidity::frontend::test;
 
-TestCaseReader::TestCaseReader(string const& _filename):
-	m_file(_filename)
-{
-	if (!m_file)
-		BOOST_THROW_EXCEPTION(runtime_error("Cannot open file: \"" + _filename + "\"."));
-	m_file.exceptions(ios::badbit);
+namespace fs = boost::filesystem;
 
-	tie(m_sources, m_lineNumber) = parseSourcesAndSettingsWithLineNumber(m_file);
+TestCaseReader::TestCaseReader(string const& _filename): m_fileStream(_filename), m_fileName(_filename)
+{
+	if (!m_fileStream)
+		BOOST_THROW_EXCEPTION(runtime_error("Cannot open file: \"" + _filename + "\"."));
+	m_fileStream.exceptions(ios::badbit);
+
+	tie(m_sources, m_lineNumber) = parseSourcesAndSettingsWithLineNumber(m_fileStream);
 	m_unreadSettings = m_settings;
 }
 
@@ -55,7 +60,7 @@ string const& TestCaseReader::source() const
 
 string TestCaseReader::simpleExpectations()
 {
-	return parseSimpleExpectations(m_file);
+	return parseSimpleExpectations(m_fileStream);
 }
 
 bool TestCaseReader::boolSetting(std::string const& _name, bool _defaultValue)
@@ -105,10 +110,12 @@ void TestCaseReader::ensureAllSettingsRead() const
 pair<SourceMap, size_t> TestCaseReader::parseSourcesAndSettingsWithLineNumber(istream& _stream)
 {
 	map<string, string> sources;
+	map<string, boost::filesystem::path> externalSources;
 	string currentSourceName;
 	string currentSource;
 	string line;
 	size_t lineNumber = 1;
+	static string const externalSourceDelimiterStart("==== ExternalSource:");
 	static string const sourceDelimiterStart("==== Source:");
 	static string const sourceDelimiterEnd("====");
 	static string const comment("// ");
@@ -137,6 +144,41 @@ pair<SourceMap, size_t> TestCaseReader::parseSourcesAndSettingsWithLineNumber(is
 				if (sources.count(currentSourceName))
 					BOOST_THROW_EXCEPTION(runtime_error("Multiple definitions of test source \"" + currentSourceName + "\"."));
 			}
+			else if (boost::algorithm::starts_with(line, externalSourceDelimiterStart) && boost::algorithm::ends_with(line, sourceDelimiterEnd))
+			{
+				string externalSourceString = boost::trim_copy(line.substr(
+					externalSourceDelimiterStart.size(),
+					line.size() - sourceDelimiterEnd.size() - externalSourceDelimiterStart.size()
+				));
+
+				string externalSourceName;
+				size_t remappingPos = externalSourceString.find('=');
+				// Does the external source define a remapping?
+				if (remappingPos != string::npos)
+				{
+					externalSourceName = boost::trim_copy(externalSourceString.substr(0, remappingPos));
+					externalSourceString = boost::trim_copy(externalSourceString.substr(remappingPos + 1));
+				}
+				else
+					externalSourceName = externalSourceString;
+
+				solAssert(!externalSourceName.empty(), "");
+				fs::path externalSourceTarget(externalSourceString);
+				fs::path testCaseParentDir = m_fileName.parent_path();
+				if (!externalSourceTarget.is_relative())
+					BOOST_THROW_EXCEPTION(runtime_error("External Source paths need to be relative to the location of the test case."));
+				fs::path externalSourceFullPath = testCaseParentDir / externalSourceTarget;
+				string externalSourceContent;
+				if (!fs::exists(externalSourceFullPath))
+					BOOST_THROW_EXCEPTION(runtime_error("External Source '" + externalSourceTarget.string() + "' not found."));
+				else
+					externalSourceContent = util::readFileAsString(externalSourceFullPath.string());
+
+				if (sources.count(externalSourceName))
+					BOOST_THROW_EXCEPTION(runtime_error("Multiple definitions of test source \"" + externalSourceName + "\"."));
+				sources[externalSourceName] = externalSourceContent;
+				externalSources[externalSourceName] = externalSourceTarget;
+			}
 			else
 				currentSource += line + "\n";
 		}
@@ -156,7 +198,7 @@ pair<SourceMap, size_t> TestCaseReader::parseSourcesAndSettingsWithLineNumber(is
 	}
 	// Register the last source as the main one
 	sources[currentSourceName] = currentSource;
-	return {{move(sources), move(currentSourceName)}, lineNumber};
+	return {{move(sources), move(externalSources), move(currentSourceName)}, lineNumber};
 }
 
 string TestCaseReader::parseSimpleExpectations(istream& _file)
diff --git a/test/TestCaseReader.h b/test/TestCaseReader.h
index 620565aee..2d0ffe3b0 100644
--- a/test/TestCaseReader.h
+++ b/test/TestCaseReader.h
@@ -16,6 +16,7 @@
 */
 // SPDX-License-Identifier: GPL-3.0
 
+#include <boost/filesystem.hpp>
 #include <fstream>
 #include <map>
 #include <string>
@@ -31,6 +32,7 @@ namespace solidity::frontend::test
 struct SourceMap
 {
 	std::map<std::string, std::string> sources;
+	std::map<std::string, boost::filesystem::path> externalSources;
 	std::string mainSourceFile;
 };
 
@@ -48,7 +50,7 @@ public:
 	std::string const& source() const;
 	std::size_t lineNumber() const { return m_lineNumber; }
 	std::map<std::string, std::string> const& settings() const { return m_settings; }
-	std::ifstream& stream() { return m_file; }
+	std::ifstream& stream() { return m_fileStream; }
 
 	std::string simpleExpectations();
 
@@ -62,7 +64,8 @@ private:
 	std::pair<SourceMap, std::size_t> parseSourcesAndSettingsWithLineNumber(std::istream& _file);
 	static std::string parseSimpleExpectations(std::istream& _file);
 
-	std::ifstream m_file;
+	std::ifstream m_fileStream;
+	boost::filesystem::path m_fileName;
 	SourceMap m_sources;
 	std::size_t m_lineNumber = 0;
 	std::map<std::string, std::string> m_settings;
diff --git a/test/boostTest.cpp b/test/boostTest.cpp
index 0162cd593..adb608da7 100644
--- a/test/boostTest.cpp
+++ b/test/boostTest.cpp
@@ -86,7 +86,10 @@ int registerTests(
 			fs::directory_iterator(fullpath),
 			fs::directory_iterator()
 		))
-			if (fs::is_directory(entry.path()) || TestCase::isTestFilename(entry.path().filename()))
+			if (
+				solidity::test::isValidSemanticTestPath(entry) &&
+				(fs::is_directory(entry.path()) || TestCase::isTestFilename(entry.path().filename()))
+			)
 				numTestsAdded += registerTests(
 					*sub_suite,
 					_basepath, _path / entry.path().filename(),
diff --git a/test/libsolidity/SemanticTest.cpp b/test/libsolidity/SemanticTest.cpp
index 7a06f0ba1..10c5742e2 100644
--- a/test/libsolidity/SemanticTest.cpp
+++ b/test/libsolidity/SemanticTest.cpp
@@ -256,7 +256,7 @@ TestCase::TestResult SemanticTest::runTest(
 			{
 				soltestAssert(
 					m_allowNonExistingFunctions ||
-					m_compiler.methodIdentifiers(m_compiler.lastContractName()).isMember(test.call().signature),
+					m_compiler.methodIdentifiers(m_compiler.lastContractName(m_sources.mainSourceFile)).isMember(test.call().signature),
 					"The function " + test.call().signature + " is not known to the compiler"
 				);
 
@@ -283,7 +283,7 @@ TestCase::TestResult SemanticTest::runTest(
 
 			test.setFailure(!m_transactionSuccessful);
 			test.setRawBytes(std::move(output));
-			test.setContractABI(m_compiler.contractABI(m_compiler.lastContractName()));
+			test.setContractABI(m_compiler.contractABI(m_compiler.lastContractName(m_sources.mainSourceFile)));
 		}
 	}
 
@@ -379,42 +379,62 @@ void SemanticTest::printSource(ostream& _stream, string const& _linePrefix, bool
 	if (m_sources.sources.empty())
 		return;
 
-	bool outputNames = (m_sources.sources.size() != 1 || !m_sources.sources.begin()->first.empty());
+	bool outputNames = (m_sources.sources.size() - m_sources.externalSources.size() != 1 || !m_sources.sources.begin()->first.empty());
+
+	set<string> externals;
+	for (auto const& [name, path]: m_sources.externalSources)
+	{
+		externals.insert(name);
+		string externalSource;
+		if (name == path)
+			externalSource = name;
+		else
+			externalSource = name + "=" + path.generic_string();
+
+		if (_formatted)
+			_stream << _linePrefix  << formatting::CYAN << "==== ExternalSource: " << externalSource << " ===="s << formatting::RESET << endl;
+		else
+			_stream << _linePrefix << "==== ExternalSource: " << externalSource << " ===="s << endl;
+	}
 
 	for (auto const& [name, source]: m_sources.sources)
-		if (_formatted)
+		if (externals.find(name) == externals.end())
 		{
-			if (source.empty())
-				continue;
-
-			if (outputNames)
-				_stream << _linePrefix << formatting::CYAN << "==== Source: " << name << " ====" << formatting::RESET << endl;
-			vector<char const*> sourceFormatting(source.length(), formatting::RESET);
-
-			_stream << _linePrefix << sourceFormatting.front() << source.front();
-			for (size_t i = 1; i < source.length(); i++)
+			if (_formatted)
 			{
-				if (sourceFormatting[i] != sourceFormatting[i - 1])
-					_stream << sourceFormatting[i];
-				if (source[i] != '\n')
-					_stream << source[i];
-				else
+				if (source.empty())
+					continue;
+
+				if (outputNames)
+					_stream << _linePrefix << formatting::CYAN << "==== Source: " << name
+							<< " ====" << formatting::RESET << endl;
+
+				vector<char const*> sourceFormatting(source.length(), formatting::RESET);
+				_stream << _linePrefix << sourceFormatting.front() << source.front();
+				for (size_t i = 1; i < source.length(); i++)
 				{
-					_stream << formatting::RESET << endl;
-					if (i + 1 < source.length())
-						_stream << _linePrefix << sourceFormatting[i];
+					if (sourceFormatting[i] != sourceFormatting[i - 1])
+						_stream << sourceFormatting[i];
+					if (source[i] != '\n')
+						_stream << source[i];
+					else
+					{
+						_stream << formatting::RESET << endl;
+						if (i + 1 < source.length())
+							_stream << _linePrefix << sourceFormatting[i];
+					}
 				}
+				_stream << formatting::RESET;
+			}
+			else
+			{
+				if (outputNames)
+					_stream << _linePrefix << "==== Source: " + name << " ====" << endl;
+				stringstream stream(source);
+				string line;
+				while (getline(stream, line))
+					_stream << _linePrefix << line << endl;
 			}
-			_stream << formatting::RESET;
-		}
-		else
-		{
-			if (outputNames)
-				_stream << _linePrefix << "==== Source: " + name << " ====" << endl;
-			stringstream stream(source);
-			string line;
-			while (getline(stream, line))
-				_stream << _linePrefix << line << endl;
 		}
 }
 
@@ -455,6 +475,6 @@ bool SemanticTest::deploy(
 	map<string, solidity::test::Address> const& _libraries
 )
 {
-	auto output = compileAndRunWithoutCheck(m_sources.sources, _value, _contractName, _arguments, _libraries);
+	auto output = compileAndRunWithoutCheck(m_sources.sources, _value, _contractName, _arguments, _libraries, m_sources.mainSourceFile);
 	return !output.empty() && m_transactionSuccessful;
 }
diff --git a/test/libsolidity/SolidityExecutionFramework.cpp b/test/libsolidity/SolidityExecutionFramework.cpp
index ab0bba27d..6ec949c68 100644
--- a/test/libsolidity/SolidityExecutionFramework.cpp
+++ b/test/libsolidity/SolidityExecutionFramework.cpp
@@ -36,10 +36,13 @@ using namespace std;
 
 bytes SolidityExecutionFramework::multiSourceCompileContract(
 	map<string, string> const& _sourceCode,
+	optional<string> const& _mainSourceName,
 	string const& _contractName,
 	map<string, Address> const& _libraryAddresses
 )
 {
+	if (_mainSourceName.has_value())
+		solAssert(_sourceCode.find(_mainSourceName.value()) != _sourceCode.end(), "");
 	map<string, string> sourcesWithPreamble = _sourceCode;
 	for (auto& entry: sourcesWithPreamble)
 		entry.second = addPreamble(entry.second);
@@ -68,7 +71,7 @@ bytes SolidityExecutionFramework::multiSourceCompileContract(
 			formatter.printErrorInformation(*error);
 		BOOST_ERROR("Compiling contract failed");
 	}
-	std::string contractName(_contractName.empty() ? m_compiler.lastContractName() : _contractName);
+	string contractName(_contractName.empty() ? m_compiler.lastContractName(_mainSourceName) : _contractName);
 	evmasm::LinkerObject obj;
 	if (m_compileViaYul)
 	{
@@ -98,7 +101,7 @@ bytes SolidityExecutionFramework::multiSourceCompileContract(
 				try
 				{
 					asmStack.optimize();
-					obj = std::move(*asmStack.assemble(yul::AssemblyStack::Machine::EVM).bytecode);
+					obj = move(*asmStack.assemble(yul::AssemblyStack::Machine::EVM).bytecode);
 					obj.link(_libraryAddresses);
 					break;
 				}
@@ -126,6 +129,7 @@ bytes SolidityExecutionFramework::compileContract(
 {
 	return multiSourceCompileContract(
 		{{"", _sourceCode}},
+		nullopt,
 		_contractName,
 		_libraryAddresses
 	);
diff --git a/test/libsolidity/SolidityExecutionFramework.h b/test/libsolidity/SolidityExecutionFramework.h
index f616b2419..e0e02cf95 100644
--- a/test/libsolidity/SolidityExecutionFramework.h
+++ b/test/libsolidity/SolidityExecutionFramework.h
@@ -49,10 +49,11 @@ public:
 		u256 const& _value = 0,
 		std::string const& _contractName = "",
 		bytes const& _arguments = {},
-		std::map<std::string, solidity::test::Address> const& _libraryAddresses = {}
+		std::map<std::string, solidity::test::Address> const& _libraryAddresses = {},
+		std::optional<std::string> const& _sourceName = std::nullopt
 	) override
 	{
-		bytes bytecode = multiSourceCompileContract(_sourceCode, _contractName, _libraryAddresses);
+		bytes bytecode = multiSourceCompileContract(_sourceCode, _sourceName, _contractName, _libraryAddresses);
 		sendMessage(bytecode + _arguments, true, _value);
 		return m_output;
 	}
@@ -65,6 +66,7 @@ public:
 
 	bytes multiSourceCompileContract(
 		std::map<std::string, std::string> const& _sources,
+		std::optional<std::string> const& _mainSourceName = std::nullopt,
 		std::string const& _contractName = "",
 		std::map<std::string, solidity::test::Address> const& _libraryAddresses = {}
 	);
diff --git a/test/libsolidity/SyntaxTest.cpp b/test/libsolidity/SyntaxTest.cpp
index 009b3613b..ed23bc609 100644
--- a/test/libsolidity/SyntaxTest.cpp
+++ b/test/libsolidity/SyntaxTest.cpp
@@ -65,7 +65,7 @@ string SyntaxTest::addPreamble(string const& _sourceCode)
 void SyntaxTest::setupCompiler()
 {
 	compiler().reset();
-	auto sourcesWithPragma = m_sources;
+	auto sourcesWithPragma = m_sources.sources;
 	for (auto& source: sourcesWithPragma)
 		source.second = addPreamble(source.second);
 	compiler().setSources(sourcesWithPragma);
@@ -122,8 +122,8 @@ void SyntaxTest::filterObtainedErrors()
 			solAssert(location->source, "");
 			sourceName = location->source->name();
 
-			solAssert(m_sources.count(sourceName) == 1, "");
-			int preambleSize = static_cast<int>(location->source->source().size()) - static_cast<int>(m_sources[sourceName].size());
+			solAssert(m_sources.sources.count(sourceName) == 1, "");
+			int preambleSize = static_cast<int>(location->source->source().size()) - static_cast<int>(m_sources.sources[sourceName].size());
 			solAssert(preambleSize >= 0, "");
 
 			// ignore the version & license pragma inserted by the testing tool when calculating locations.
diff --git a/test/libsolidity/semanticTests/externalSource/_external/external.sol b/test/libsolidity/semanticTests/externalSource/_external/external.sol
new file mode 100644
index 000000000..3289e6ec9
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/external.sol
@@ -0,0 +1,2 @@
+contract External {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_external/external.sol=sol b/test/libsolidity/semanticTests/externalSource/_external/external.sol=sol
new file mode 100644
index 000000000..3289e6ec9
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/external.sol=sol
@@ -0,0 +1,2 @@
+contract External {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_external/import.sol b/test/libsolidity/semanticTests/externalSource/_external/import.sol
new file mode 100644
index 000000000..30915351e
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/import.sol
@@ -0,0 +1,2 @@
+import "external.sol";
+import "other_external.sol";
diff --git a/test/libsolidity/semanticTests/externalSource/_external/import_with_subdir.sol b/test/libsolidity/semanticTests/externalSource/_external/import_with_subdir.sol
new file mode 100644
index 000000000..a8e23be56
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/import_with_subdir.sol
@@ -0,0 +1 @@
+import "subdir/import.sol";
diff --git a/test/libsolidity/semanticTests/externalSource/_external/other_external.sol b/test/libsolidity/semanticTests/externalSource/_external/other_external.sol
new file mode 100644
index 000000000..7a686b3dc
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/other_external.sol
@@ -0,0 +1,2 @@
+contract OtherExternal {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_external/subdir/import.sol b/test/libsolidity/semanticTests/externalSource/_external/subdir/import.sol
new file mode 100644
index 000000000..bf0ef42ce
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/subdir/import.sol
@@ -0,0 +1 @@
+import "sub_external.sol";
diff --git a/test/libsolidity/semanticTests/externalSource/_external/subdir/sub_external.sol b/test/libsolidity/semanticTests/externalSource/_external/subdir/sub_external.sol
new file mode 100644
index 000000000..63a3bd180
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_external/subdir/sub_external.sol
@@ -0,0 +1,2 @@
+contract SubExternal {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/a.sol b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/a.sol
new file mode 100644
index 000000000..4e829399a
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/a.sol
@@ -0,0 +1,2 @@
+contract A {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/c.sol b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/c.sol
new file mode 100644
index 000000000..41a6d5677
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/c.sol
@@ -0,0 +1,2 @@
+contract C {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/d.sol b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/d.sol
new file mode 100644
index 000000000..0c9cba07d
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_non_normalized_paths/d.sol
@@ -0,0 +1,2 @@
+contract D {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/D/d.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/D/d.sol
new file mode 100644
index 000000000..0c9cba07d
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/D/d.sol
@@ -0,0 +1,2 @@
+contract D {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/c.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/c.sol
new file mode 100644
index 000000000..41a6d5677
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/c.sol
@@ -0,0 +1,2 @@
+contract C {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/B/b.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/B/b.sol
new file mode 100644
index 000000000..5611e6fa3
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/B/b.sol
@@ -0,0 +1,3 @@
+import {C} from "../../c.sol";
+contract B {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/G/g.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/G/g.sol
new file mode 100644
index 000000000..1d2096de2
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/G/g.sol
@@ -0,0 +1,3 @@
+import {B} from "../B/b.sol";
+contract G {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/a.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/a.sol
new file mode 100644
index 000000000..4e829399a
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/a.sol
@@ -0,0 +1,2 @@
+contract A {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/contract.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/contract.sol
new file mode 100644
index 000000000..aab81b975
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/dir/contract.sol
@@ -0,0 +1,8 @@
+import {A} from "./a.sol";
+import {B} from "./B/b.sol";
+import {C} from "../c.sol";
+import {D} from "../D/d.sol";
+import {G} from "./E/../F/../G/./g.sol";
+import {H} from "../../../../_relative_imports/h.sol";
+contract Contract {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_relative_imports/h.sol b/test/libsolidity/semanticTests/externalSource/_relative_imports/h.sol
new file mode 100644
index 000000000..2d969980e
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_relative_imports/h.sol
@@ -0,0 +1,2 @@
+contract H {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/b.sol b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/b.sol
new file mode 100644
index 000000000..8b4d63952
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/b.sol
@@ -0,0 +1,2 @@
+contract B {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/a.sol b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/a.sol
new file mode 100644
index 000000000..4e829399a
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/a.sol
@@ -0,0 +1,2 @@
+contract A {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/contract.sol b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/contract.sol
new file mode 100644
index 000000000..f67d97026
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dir/contract.sol
@@ -0,0 +1,2 @@
+import {A} from "./a.sol";
+import {B} from "../b.sol";
diff --git a/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_a.sol b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_a.sol
new file mode 100644
index 000000000..3f1554224
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_a.sol
@@ -0,0 +1,2 @@
+contract Dot_A {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_dot_b.sol b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_dot_b.sol
new file mode 100644
index 000000000..037c81216
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/_source_name_starting_with_dots/dot_dot_b.sol
@@ -0,0 +1,2 @@
+contract Dot_Dot_B {
+}
diff --git a/test/libsolidity/semanticTests/externalSource/multiple_equals_signs.sol b/test/libsolidity/semanticTests/externalSource/multiple_equals_signs.sol
new file mode 100644
index 000000000..d6bd1e27c
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/multiple_equals_signs.sol
@@ -0,0 +1,8 @@
+==== ExternalSource: a=_external/external.sol=sol ====
+import {External} from "a";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/multiple_external_source.sol b/test/libsolidity/semanticTests/externalSource/multiple_external_source.sol
new file mode 100644
index 000000000..4b4c3d9bb
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/multiple_external_source.sol
@@ -0,0 +1,10 @@
+==== ExternalSource: _external/external.sol ====
+==== ExternalSource: _external/other_external.sol ====
+import {External} from "_external/external.sol";
+import {OtherExternal} from "_external/other_external.sol";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/multisource.sol b/test/libsolidity/semanticTests/externalSource/multisource.sol
new file mode 100644
index 000000000..8291f66ae
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/multisource.sol
@@ -0,0 +1,14 @@
+==== ExternalSource: _external/external.sol ====
+==== Source: s1.sol ====
+import {External} from "_external/external.sol";
+contract S1 {
+}
+==== Source: s2.sol ====
+import {S1} from "s1.sol";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
+
diff --git a/test/libsolidity/semanticTests/externalSource/non_normalized_paths.sol b/test/libsolidity/semanticTests/externalSource/non_normalized_paths.sol
new file mode 100644
index 000000000..4d1854e96
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/non_normalized_paths.sol
@@ -0,0 +1,12 @@
+==== ExternalSource: _non_normalized_paths//a.sol ====
+==== ExternalSource: C/////c.sol=_non_normalized_paths/c.sol ====
+==== ExternalSource: C/../////D/d.sol=_non_normalized_paths///d.sol ====
+import {A} from "_non_normalized_paths//a.sol";
+import {C} from "C/////c.sol";
+import {D} from "C/../////D/d.sol";
+contract Contract {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/relative_imports.sol b/test/libsolidity/semanticTests/externalSource/relative_imports.sol
new file mode 100644
index 000000000..744684f4f
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/relative_imports.sol
@@ -0,0 +1,14 @@
+==== ExternalSource: _relative_imports/dir/contract.sol ====
+==== ExternalSource: _relative_imports/dir/a.sol ====
+==== ExternalSource: _relative_imports/dir/B/b.sol ====
+==== ExternalSource: _relative_imports/c.sol ====
+==== ExternalSource: _relative_imports/D/d.sol ====
+==== ExternalSource: _relative_imports/dir/G/g.sol ====
+==== ExternalSource: _relative_imports/h.sol ====
+import {A, B, C, D, G, H, Contract} from "_relative_imports/dir/contract.sol";
+contract CC {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/source.sol b/test/libsolidity/semanticTests/externalSource/source.sol
new file mode 100644
index 000000000..5fc5a3b89
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/source.sol
@@ -0,0 +1,8 @@
+==== ExternalSource: _external/external.sol ====
+import {External} from "_external/external.sol";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/source_import.sol b/test/libsolidity/semanticTests/externalSource/source_import.sol
new file mode 100644
index 000000000..4b4c3d9bb
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/source_import.sol
@@ -0,0 +1,10 @@
+==== ExternalSource: _external/external.sol ====
+==== ExternalSource: _external/other_external.sol ====
+import {External} from "_external/external.sol";
+import {OtherExternal} from "_external/other_external.sol";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/source_import_subdir.sol b/test/libsolidity/semanticTests/externalSource/source_import_subdir.sol
new file mode 100644
index 000000000..f3fa73085
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/source_import_subdir.sol
@@ -0,0 +1,10 @@
+==== ExternalSource: _external/import_with_subdir.sol ====
+==== ExternalSource: subdir/import.sol=_external/subdir/import.sol ====
+==== ExternalSource: sub_external.sol=_external/subdir/sub_external.sol ====
+import {SubExternal} from "sub_external.sol";
+contract C {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/source_name_starting_with_dots.sol b/test/libsolidity/semanticTests/externalSource/source_name_starting_with_dots.sol
new file mode 100644
index 000000000..829485e6d
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/source_name_starting_with_dots.sol
@@ -0,0 +1,12 @@
+==== ExternalSource: ./a.sol=_source_name_starting_with_dots/dot_a.sol ====
+==== ExternalSource: ../b.sol=_source_name_starting_with_dots/dot_dot_b.sol ====
+==== ExternalSource: _source_name_starting_with_dots/dir/a.sol ====
+==== ExternalSource: _source_name_starting_with_dots/b.sol ====
+==== ExternalSource: _source_name_starting_with_dots/dir/contract.sol ====
+import {A, B} from "_source_name_starting_with_dots/dir/contract.sol";
+contract Contract {
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libsolidity/semanticTests/externalSource/source_remapping.sol b/test/libsolidity/semanticTests/externalSource/source_remapping.sol
new file mode 100644
index 000000000..4edb2200f
--- /dev/null
+++ b/test/libsolidity/semanticTests/externalSource/source_remapping.sol
@@ -0,0 +1,12 @@
+==== ExternalSource: ExtSource.sol=_external/external.sol ====
+==== ExternalSource: /ExtSource.sol=_external/other_external.sol ====
+import "ExtSource.sol";
+import "/ExtSource.sol";
+contract C {
+    External _external;
+    OtherExternal _otherExternal;
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
diff --git a/test/libyul/SyntaxTest.cpp b/test/libyul/SyntaxTest.cpp
index f01728571..21d295058 100644
--- a/test/libyul/SyntaxTest.cpp
+++ b/test/libyul/SyntaxTest.cpp
@@ -25,6 +25,7 @@
 
 #include <test/libyul/Common.h>
 #include <test/libyul/SyntaxTest.h>
+#include <test/TestCaseReader.h>
 
 #include <test/libsolidity/util/SoltestErrors.h>
 
@@ -35,14 +36,15 @@ using namespace solidity;
 using namespace solidity::util;
 using namespace solidity::langutil;
 using namespace solidity::yul::test;
+using namespace solidity::frontend::test;
 
 void SyntaxTest::parseAndAnalyze()
 {
-	if (m_sources.size() != 1)
+	if (m_sources.sources.size() != 1)
 		BOOST_THROW_EXCEPTION(runtime_error{"Expected only one source for yul test."});
 
-	string const& name = m_sources.begin()->first;
-	string const& source = m_sources.begin()->second;
+	string const& name = m_sources.sources.begin()->first;
+	string const& source = m_sources.sources.begin()->second;
 
 	ErrorList errorList{};
 	soltestAssert(m_dialect, "");
diff --git a/test/tools/isoltest.cpp b/test/tools/isoltest.cpp
index b05cbe84a..31f674876 100644
--- a/test/tools/isoltest.cpp
+++ b/test/tools/isoltest.cpp
@@ -79,9 +79,9 @@ public:
 		m_filterExpression = regex{"(" + filter + "(\\.sol|\\.yul))"};
 	}
 
-	bool matches(string const& _name) const
+	bool matches(fs::path const& _path, string const& _name) const
 	{
-		return regex_match(_name, m_filterExpression);
+		return regex_match(_name, m_filterExpression) && solidity::test::isValidSemanticTestPath(_path);
 	}
 
 private:
@@ -154,7 +154,7 @@ TestTool::Result TestTool::process()
 
 	try
 	{
-		if (m_filter.matches(m_name))
+		if (m_filter.matches(m_path, m_name))
 		{
 			(AnsiColorized(cout, formatted, {BOLD}) << m_name << ": ").flush();