diff --git a/Sources/SKCore/BuildServerBuildSystem.swift b/Sources/SKCore/BuildServerBuildSystem.swift
index fba894d7..328d3d64 100644
--- a/Sources/SKCore/BuildServerBuildSystem.swift
+++ b/Sources/SKCore/BuildServerBuildSystem.swift
@@ -35,6 +35,9 @@ public final class BuildServerBuildSystem {
   public private(set) var indexDatabasePath: AbsolutePath?
   public private(set) var indexStorePath: AbsolutePath?
 
+  // FIXME: Add support for prefix mappings to the Build Server protocol.
+  public var indexPrefixMappings: [PathPrefixMapping] { return [] }
+
   /// Delegate to handle any build system events.
   public weak var delegate: BuildSystemDelegate? {
     get { return self.handler?.delegate }
diff --git a/Sources/SKCore/BuildSystem.swift b/Sources/SKCore/BuildSystem.swift
index 094d368c..5ecf15c6 100644
--- a/Sources/SKCore/BuildSystem.swift
+++ b/Sources/SKCore/BuildSystem.swift
@@ -43,6 +43,9 @@ public protocol BuildSystem: AnyObject {
   /// The path to put the index database, if any.
   var indexDatabasePath: AbsolutePath? { get }
 
+  /// Path remappings for remapping index data for local use.
+  var indexPrefixMappings: [PathPrefixMapping] { get }
+
   /// Delegate to handle any build system events such as file build settings
   /// initial reports as well as changes.
   var delegate: BuildSystemDelegate? { get set }
diff --git a/Sources/SKCore/BuildSystemManager.swift b/Sources/SKCore/BuildSystemManager.swift
index d7727c01..c012e75c 100644
--- a/Sources/SKCore/BuildSystemManager.swift
+++ b/Sources/SKCore/BuildSystemManager.swift
@@ -140,6 +140,8 @@ extension BuildSystemManager: BuildSystem {
 
   public var indexDatabasePath: AbsolutePath? { queue.sync { buildSystem?.indexDatabasePath } }
 
+  public var indexPrefixMappings: [PathPrefixMapping] { queue.sync { buildSystem?.indexPrefixMappings ?? [] } }
+
   public var delegate: BuildSystemDelegate? {
     get { queue.sync { _delegate } }
     set { queue.sync { _delegate = newValue } }
diff --git a/Sources/SKCore/CMakeLists.txt b/Sources/SKCore/CMakeLists.txt
index 7cd686d4..5281bf85 100644
--- a/Sources/SKCore/CMakeLists.txt
+++ b/Sources/SKCore/CMakeLists.txt
@@ -12,6 +12,7 @@ add_library(SKCore STATIC
   FileBuildSettingsChange.swift
   LanguageServer.swift
   MainFilesProvider.swift
+  PathPrefixMapping.swift
   Toolchain.swift
   ToolchainRegistry.swift
   XCToolchainPlist.swift)
diff --git a/Sources/SKCore/CompilationDatabaseBuildSystem.swift b/Sources/SKCore/CompilationDatabaseBuildSystem.swift
index 1bb46fc6..7a3287cc 100644
--- a/Sources/SKCore/CompilationDatabaseBuildSystem.swift
+++ b/Sources/SKCore/CompilationDatabaseBuildSystem.swift
@@ -88,6 +88,8 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
     indexStorePath?.parentDirectory.appending(component: "IndexDatabase")
   }
 
+  public var indexPrefixMappings: [PathPrefixMapping] { return [] }
+
   public func registerForChangeNotifications(for uri: DocumentURI, language: Language) {
     queue.async {
       self.watchedFiles[uri] = language
diff --git a/Sources/SKCore/FallbackBuildSystem.swift b/Sources/SKCore/FallbackBuildSystem.swift
index ceb6cade..5f5d28ee 100644
--- a/Sources/SKCore/FallbackBuildSystem.swift
+++ b/Sources/SKCore/FallbackBuildSystem.swift
@@ -40,6 +40,8 @@ public final class FallbackBuildSystem: BuildSystem {
 
   public var indexDatabasePath: AbsolutePath? { return nil }
 
+  public var indexPrefixMappings: [PathPrefixMapping] { return [] }
+
   public func settings(for uri: DocumentURI, _ language: Language) -> FileBuildSettings? {
     switch language {
     case .swift:
diff --git a/Sources/SKCore/PathPrefixMapping.swift b/Sources/SKCore/PathPrefixMapping.swift
new file mode 100644
index 00000000..ac71f4f2
--- /dev/null
+++ b/Sources/SKCore/PathPrefixMapping.swift
@@ -0,0 +1,14 @@
+import Foundation
+
+public struct PathPrefixMapping {
+  /// Path prefix to be replaced, typically the canonical or hermetic path.
+  public let original: String
+
+  /// Replacement path prefix, typically the path on the local machine.
+  public let replacement: String
+
+  public init(original: String, replacement: String) {
+    self.original = original
+    self.replacement = replacement
+  }
+}
diff --git a/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift b/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
index e542fd02..779a179c 100644
--- a/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
+++ b/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
@@ -240,6 +240,8 @@ extension SwiftPMWorkspace: SKCore.BuildSystem {
     return buildPath.appending(components: "index", "db")
   }
 
+  public var indexPrefixMappings: [PathPrefixMapping] { return [] }
+
   /// **Public for testing only**
   public func _settings(
     for uri: DocumentURI,
diff --git a/Sources/SourceKitLSP/Workspace.swift b/Sources/SourceKitLSP/Workspace.swift
index edaec13d..957717e5 100644
--- a/Sources/SourceKitLSP/Workspace.swift
+++ b/Sources/SourceKitLSP/Workspace.swift
@@ -112,12 +112,14 @@ public final class Workspace {
       do {
         let lib = try IndexStoreLibrary(dylibPath: libPath.pathString)
         indexDelegate = SourceKitIndexDelegate()
+        let prefixMappings = indexOptions.indexPrefixMappings ?? buildSystem?.indexPrefixMappings ?? []
         index = try IndexStoreDB(
           storePath: storePath.pathString,
           databasePath: dbPath.pathString,
           library: lib,
           delegate: indexDelegate,
-          listenToUnitEvents: indexOptions.listenToUnitEvents)
+          listenToUnitEvents: indexOptions.listenToUnitEvents,
+          prefixMappings: prefixMappings.map { PathMapping(original: $0.original, replacement: $0.replacement) })
         log("opened IndexStoreDB at \(dbPath) with store path \(storePath)")
       } catch {
         log("failed to open IndexStoreDB: \(error.localizedDescription)", level: .error)
@@ -144,11 +146,22 @@ public struct IndexOptions {
   /// Override the index-database-path provided by the build system.
   public var indexDatabasePath: AbsolutePath?
 
+  /// Override the index prefix mappings provided by the build system.
+  public var indexPrefixMappings: [PathPrefixMapping]?
+
   /// *For Testing* Whether the index should listen to unit events, or wait for
   /// explicit calls to pollForUnitChangesAndWait().
   public var listenToUnitEvents: Bool
 
-  public init(indexStorePath: AbsolutePath? = nil, indexDatabasePath: AbsolutePath? = nil, listenToUnitEvents: Bool = true) {
+  public init(
+    indexStorePath: AbsolutePath? = nil,
+    indexDatabasePath: AbsolutePath? = nil,
+    indexPrefixMappings: [PathPrefixMapping]? = nil,
+    listenToUnitEvents: Bool = true
+  ) {
+    self.indexStorePath = indexStorePath
+    self.indexDatabasePath = indexDatabasePath
+    self.indexPrefixMappings = indexPrefixMappings
     self.listenToUnitEvents = listenToUnitEvents
   }
 }
diff --git a/Sources/sourcekit-lsp/main.swift b/Sources/sourcekit-lsp/main.swift
index 8f0828d4..361cf52a 100644
--- a/Sources/sourcekit-lsp/main.swift
+++ b/Sources/sourcekit-lsp/main.swift
@@ -41,6 +41,14 @@ extension AbsolutePath: ExpressibleByArgument {
   }
 }
 
+extension PathPrefixMapping: ExpressibleByArgument {
+  public init?(argument: String) {
+    guard let eqIndex = argument.firstIndex(of: "=") else { return nil }
+    self.init(original: String(argument[..<eqIndex]),
+              replacement: String(argument[argument.index(after: eqIndex)...]))
+  }
+}
+
 extension LogLevel: ExpressibleByArgument {}
 extension BuildConfiguration: ExpressibleByArgument {}
 
@@ -113,6 +121,14 @@ struct Main: ParsableCommand {
   )
   var indexDatabasePath: AbsolutePath?
 
+  @Option(
+    name: .customLong("index-prefix-map", withSingleDash: true),
+    parsing: .unconditionalSingleValue,
+    help: "Override the prefix map from the build system, values of form 'remote=local'"
+  )
+  var indexPrefixMappings = [PathPrefixMapping]()
+
+
   @Option(
     help: "Whether to enable server-side filtering in code-completion"
   )
@@ -135,6 +151,7 @@ struct Main: ParsableCommand {
     serverOptions.clangdOptions = clangdOptions
     serverOptions.indexOptions.indexStorePath = indexStorePath
     serverOptions.indexOptions.indexDatabasePath = indexDatabasePath
+    serverOptions.indexOptions.indexPrefixMappings = indexPrefixMappings
     serverOptions.completionOptions.serverSideFiltering = completionServerSideFiltering
     serverOptions.completionOptions.maxResults = completionMaxResults
 
diff --git a/Tests/SKCoreTests/BuildSystemManagerTests.swift b/Tests/SKCoreTests/BuildSystemManagerTests.swift
index 1f88a368..3d41e787 100644
--- a/Tests/SKCoreTests/BuildSystemManagerTests.swift
+++ b/Tests/SKCoreTests/BuildSystemManagerTests.swift
@@ -489,6 +489,7 @@ class ManualBuildSystem: BuildSystem {
 
   var indexStorePath: AbsolutePath? { nil }
   var indexDatabasePath: AbsolutePath? { nil }
+  var indexPrefixMappings: [PathPrefixMapping] { return [] }
 
   func buildTargets(reply: @escaping (LSPResult<[BuildTarget]>) -> Void) {
     fatalError()
diff --git a/Tests/SourceKitLSPTests/BuildSystemTests.swift b/Tests/SourceKitLSPTests/BuildSystemTests.swift
index fbaadc83..45318375 100644
--- a/Tests/SourceKitLSPTests/BuildSystemTests.swift
+++ b/Tests/SourceKitLSPTests/BuildSystemTests.swift
@@ -27,6 +27,7 @@ typealias LSPNotification = LanguageServerProtocol.Notification
 final class TestBuildSystem: BuildSystem {
   var indexStorePath: AbsolutePath? = nil
   var indexDatabasePath: AbsolutePath? = nil
+  var indexPrefixMappings: [PathPrefixMapping] = []
 
   weak var delegate: BuildSystemDelegate?