diff --git a/include/slang/driver/SourceLoader.h b/include/slang/driver/SourceLoader.h
index f84868bb3..c80964add 100644
--- a/include/slang/driver/SourceLoader.h
+++ b/include/slang/driver/SourceLoader.h
@@ -17,6 +17,7 @@
 
 #include "slang/syntax/SyntaxFwd.h"
 #include "slang/text/Glob.h"
+#include "slang/text/SourceLocation.h"
 #include "slang/util/Hash.h"
 #include "slang/util/Util.h"
 
@@ -66,6 +67,9 @@ class SLANG_EXPORT SourceLoader {
     SourceLoader(const SourceLoader& other) = delete;
     SourceLoader(SourceLoader&& other) = default;
 
+    /// @brief Adds a pre-loaded buffer
+    void addBuffer(SourceBuffer buffer);
+
     /// @brief Adds files to be loaded, specified via the given @a pattern.
     ///
     /// All of the files that match the pattern will be added for loading.
@@ -159,6 +163,10 @@ class SLANG_EXPORT SourceLoader {
         // The filesystem path (as specified by the user).
         std::filesystem::path path;
 
+        // An optional pre-loaded buffer for when the source doesn't originate
+        // from the filesystem
+        SourceBuffer preloadedBuffer;
+
         // The library to which the file belongs, if any.
         const SourceLibrary* library = nullptr;
 
@@ -186,8 +194,11 @@ class SLANG_EXPORT SourceLoader {
 
         FileEntry(std::filesystem::path&& path, bool isLibraryFile, const SourceLibrary* library,
                   const UnitEntry* unit, GlobRank libraryRank) :
-            path(std::move(path)), library(library), unit(unit), libraryRank(libraryRank),
-            isLibraryFile(isLibraryFile) {}
+            path(std::move(path)), preloadedBuffer(), library(library), unit(unit),
+            libraryRank(libraryRank), isLibraryFile(isLibraryFile) {}
+
+        FileEntry(SourceBuffer buffer) :
+            preloadedBuffer(buffer), libraryRank(GlobRank::ExactPath) {}
     };
 
     // The result of a loadAndParse call.
diff --git a/source/driver/SourceLoader.cpp b/source/driver/SourceLoader.cpp
index a2fd7506b..a006b6d88 100644
--- a/source/driver/SourceLoader.cpp
+++ b/source/driver/SourceLoader.cpp
@@ -31,6 +31,10 @@ SourceLoader::SourceLoader(SourceManager& sourceManager) : sourceManager(sourceM
         searchExtensions.emplace_back(ext);
 }
 
+void SourceLoader::addBuffer(SourceBuffer buffer) {
+    fileEntries.emplace_back(buffer);
+}
+
 void SourceLoader::addFiles(std::string_view pattern) {
     addFilesInternal(pattern, {}, /* isLibraryFile */ false, /* library */ nullptr,
                      /* unit */ nullptr,
@@ -157,7 +161,12 @@ std::vector<SourceBuffer> SourceLoader::loadSources() {
     results.reserve(fileEntries.size());
 
     for (auto& entry : fileEntries) {
-        auto buffer = sourceManager.readSource(entry.path, entry.library);
+        SourceManager::BufferOrError buffer;
+        if (!entry.preloadedBuffer)
+            buffer = sourceManager.readSource(entry.path, entry.library);
+        else
+            buffer = entry.preloadedBuffer;
+
         if (!buffer)
             addError(entry.path, buffer.error());
         else
@@ -527,7 +536,12 @@ SourceLoader::LoadResult SourceLoader::loadAndParse(const FileEntry& entry, cons
                                                     uint64_t fileSortKey) {
     // TODO: error if secondLib is set
 
-    auto buffer = sourceManager.readSource(entry.path, entry.library, fileSortKey);
+    SourceManager::BufferOrError buffer;
+    if (entry.preloadedBuffer)
+        buffer = entry.preloadedBuffer;
+    else
+        buffer = sourceManager.readSource(entry.path, entry.library, fileSortKey);
+
     if (!buffer)
         return std::pair{&entry, buffer.error()};